Relevant bibliographies by topics / Polymer backbone

Academic literature on the topic 'Polymer backbone'

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Published: 9 March 2023
Last updated: 10 March 2023

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Journal articles on the topic "Polymer backbone"

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Saha, Debasish, Karthik R. Peddireddy, Jürgen Allgaier, Wei Zhang, Simona Maccarrone, Henrich Frielinghaus, and Dieter Richter. "Amphiphilic Comb Polymers as New Additives in Bicontinuous Microemulsions." Nanomaterials 10, no. 12 (December 2, 2020): 2410. http://dx.doi.org/10.3390/nano10122410.

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It has been shown that the thermodynamics of bicontinuous microemulsions can be tailored via the addition of various different amphiphilic polymers. In this manuscript, we now focus on comb-type polymers consisting of hydrophobic backbones and hydrophilic side chains. The distinct philicity of the backbone and side chains leads to a well-defined segregation into the oil and water domains respectively, as confirmed by contrast variation small-angle neutron scattering experiments. This polymer–microemulsion structure leads to well-described conformational entropies of the polymer fragments (backbone and side chains) that exert pressure on the membrane, which influences the thermodynamics of the overall microemulsion. In the context of the different polymer architectures that have been studied by our group with regards to their phase diagrams and small-angle neutron scattering, the microemulsion thermodynamics of comb polymers can be described in terms of a superposition of the backbone and side chain fragments. The denser or longer the side chain, the stronger the grafting and the more visible the brush effect of the side chains becomes. Possible applications of the comb polymers as switchable additives are discussed. Finally, a balanced philicity of polymers also motivates transmembrane migration in biological systems of the polymers themselves or of polymer–DNA complexes.
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Kot, E., R. K. K. Saini, L. R. R. Norman, and A. Bismarck. "Novel Drag-Reducing Agents for Fracturing Treatments Based on Polyacrylamide Containing Weak Labile Links in the Polymer Backbone." SPE Journal 17, no. 03 (September 4, 2012): 924–30. http://dx.doi.org/10.2118/141257-pa.

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Summary Water-soluble polymers have found extensive use in the oil and gas industry. For instance, high-molecular-weight polymers are very efficient drag-/friction-reducing agents and viscosifiers. Unfortunately, the adsorption of the polymer on the reservoir formation reduces the effectiveness of the recovery of oil and gas from low-permeability formations, such as shale. The availability of water-soluble polymers containing weak links in the backbone of the polymer that can be degraded upon experiencing a certain trigger, such as temperature, pH, or reducing agent, would be very advantageous. Because of the ability of weak links to degrade under certain conditions, such polymers can be used for their intended application and can afterward be degraded in a controlled and predetermined way. The resulting lower-molecular-weight fractions of that polymer lead to a reduced viscosity and quick partitioning into the water phase, and they are also less likely to adsorb onto formation surfaces. Additionally, no oxidizers need to be pumped to break or clean the deposited polymer, thus saving treatment time. It has been proved that using a bifunctional reducing agent containing degradable groups and oxidizing metal ions as a redox couple is an effective method to initiate free-radical polymerization and build degradable groups into the backbone of vinyl polymers. Temperature-degradable but hydrolytically stable azo groups showed the most-desirable results. The presence of azo groups in the backbone of the synthesized polyacrylamide (PAM) was confirmed by H1-NMR spectra and differential scanning calorimetry (DSC). The degradation behavior of the PAM with temperature-sensitive azo groups was characterized using gel permeation chromatography (GPC) and proved that multiple labile links were built into the polymer backbone. It was also found that PAM with azo links in the polymer backbone is as good a drag-reducing agent as pure PAM. However, PAM with azo links in the backbone loses its drag-reduction properties once subjected to elevated temperatures, which for some applications is viewed as an advantage.
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Kanatieva, Anastasiia Yu, Dmitry A. Alentiev, Valeria E. Shiryaeva, Alexander A. Korolev, and Alexander A. Kurganov. "Impact of the Polymer Backbone Structure on the Separation Properties of New Stationary Phases Based on Tricyclononenes." Polymers 14, no. 23 (November 24, 2022): 5120. http://dx.doi.org/10.3390/polym14235120.

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The main purpose of this paper is to compare the chromatographic properties of capillary columns prepared with polymers with different backbone structures and to demonstrate the possibility of polymer differentiation via inverse gas chromatography. With the use of addition and metathesis types of polymerization of tricyclononenes, two new stationary phases were prepared. The metathesis polymer contained double bonds in the polymeric backbone while the backbone of the addition polymer was fully saturated and relatively mobile. A comparison of the separation and adsorption properties of new phases with conventional gas chromatography (GC) stationary phases clearly indicated their non-polar characteristics. However, the difference in the polymer structure appeared to have very little effect on the stationary phase separation properties, so other parameters were used for polymer characterization. The thermodynamic parameters of the sorption of alkanes and aromatic compounds in both polymeric stationary phases were also very similar; however, the entropy of sorption for hydrocarbons with seven or more carbon atoms was different for the two polymers. An evaluation of the specific surface energy of the stationary phases also allowed us to discriminate the two stationary phases.
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Park, Kyung Sun, Justin J. Kwok, Rishat Dilmurat, Ge Qu, Prapti Kafle, Xuyi Luo, Seok-Heon Jung, et al. "Tuning conformation, assembly, and charge transport properties of conjugated polymers by printing flow." Science Advances 5, no. 8 (August 2019): eaaw7757. http://dx.doi.org/10.1126/sciadv.aaw7757.

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Intrachain charge transport is unique to conjugated polymers distinct from inorganic and small molecular semiconductors and is key to achieving high-performance organic electronics. Polymer backbone planarity and thin film morphology sensitively modulate intrachain charge transport. However, simple, generic nonsynthetic approaches for tuning backbone planarity and the ensuing multiscale assembly process do not exist. We first demonstrate that printing flow is capable of planarizing the originally twisted polymer backbone to substantially increase the conjugation length. This conformation change leads to a marked morphological transition from chiral, twinned domains to achiral, highly aligned morphology, hence a fourfold increase in charge carrier mobilities. We found a surprising mechanism that flow extinguishes a lyotropic twist-bend mesophase upon backbone planarization, leading to the observed morphology and electronic structure transitions.
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Li, Zongze, Gregory M. Treich, Mattewos Tefferi, Chao Wu, Shamima Nasreen, Sydney K. Scheirey, Rampi Ramprasad, Gregory A. Sotzing, and Yang Cao. "High energy density and high efficiency all-organic polymers with enhanced dipolar polarization." Journal of Materials Chemistry A 7, no. 25 (2019): 15026–30. http://dx.doi.org/10.1039/c9ta03601f.

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Lv, Lei, Xiaofen Wang, Tao Dong, Xinlong Wang, Xiaoxi Wu, Lei Yang, and Hui Huang. "Significantly improving the efficiency of polymer solar cells through incorporating noncovalent conformational locks." Materials Chemistry Frontiers 1, no. 7 (2017): 1317–23. http://dx.doi.org/10.1039/c6qm00296j.

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Wang, Yu, Yudong Wang, Sushant Sahu, August A. Gallo, and Xiao-Dong Zhou. "Efficient Synthesis of High-Performance Anion Exchange Membranes by Applying Clickable Tetrakis(dialkylamino)phosphonium Cations." Polymers 15, no. 2 (January 9, 2023): 352. http://dx.doi.org/10.3390/polym15020352.

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Tetrakis(dialkylamino)phosphonium (TKDAAP) compounds exhibit extraordinary base resistance, a prerequisite feature for high-performance anion exchange membranes (AEMs). It is, however, challenging to synthesize a TKDAAP compound with reactive functionality that can be used to link the cation to a polymer backbone. In this study, two TKDAAP compounds with alkyne functionality were synthesized and incorporated into an azide-modified SBS triblock copolymer backbone via Cu(I)-catalyzed alkyne–azide cycloaddition (CuAAC) “click” chemistry. The properties of the resulting AEMs were characterized. It was found that (1) the triazole linker between the cation and the polymer backbone was stable under alkaline conditions; (2) varying the substituents of TKDAAP compounds could dramatically alter the stability; and (3) increasing the hydrophilicity of the AEM was an efficient way to enhance its ionic conductivity. Using clickable TKDAAP compounds makes it easy to combine various cations into polymer backbones with adjustable cation content, thus potentially leading to an efficient way to screen a wide variety of polyelectrolyte structures to identify the most promising candidates for high-performance AEMs.
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Hou, Qiong, Jie Luo, Sui Lian Luo, Hong Zhu, and Guang Shi. "White Electroluminescence from a Single Fluorene-Based Copolymer." Advanced Materials Research 160-162 (November 2010): 732–36. http://dx.doi.org/10.4028/www.scientific.net/amr.160-162.732.

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White light emitting polymers were synthesized through incorporating of low-band gap red light emitting 4,7-di(4-hexyl-thien-2-yl)-2,1,3-benzothiadiazole (DHTBT) moieties into the backbone of a blue-light-emitting poly(9,9-dioctylfluorene) (PFO). Incomplete energy transfer from the blue electroluminescent PFO backbone to the red light emitting unit occurred by carefully controlling the relative content of the low-band gap unit DHTBT in the resulting polymers. Pure white light electroluminescence from a single polymer has been obtained in a device with a configuration of ITO/PVK/polymer/Ba/Al.The highest external quantum efficiency is 1.04% at the luminance of 249 cd/m2 for the white emitting polymer with color coordinates (0.30, 0.35) very close to the CIE coordinates for National Television System Committee (NTSC) standard white-light emission (0.33,0.33).
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Chen, Bing, Zhanhai Xiao, Yanhu Li, Lei Yu, Wei Yang, and Jiwen Feng. "Bipolar π-conjugation interrupted host polymers by metal-free superacid-catalyzed polymerization for single-layer electrophosphorescent diodes." RSC Adv. 4, no. 91 (2014): 50027–34. http://dx.doi.org/10.1039/c4ra06540a.

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O’Harra, Kathryn E., Danielle M. Noll, Irshad Kammakakam, Emily M. DeVriese, Gala Solis, Enrique M. Jackson, and Jason E. Bara. "Designing Imidazolium Poly(amide-amide) and Poly(amide-imide) Ionenes and Their Interactions with Mono- and Tris(imidazolium) Ionic Liquids." Polymers 12, no. 6 (May 30, 2020): 1254. http://dx.doi.org/10.3390/polym12061254.

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Here we introduce the synthesis and thermal properties of a series of sophisticated imidazolium ionenes with alternating amide-amide or amide-imide backbone functionality, and investigate the structural effects of mono(imidazolium) and unprecedented tris(imidazolium) ionic liquids (ILs) in these ionenes. The new set of poly(amide-amide) (PAA) and poly(amide-imide) (PAI) ionenes represent the intersection of conventional high-performance polymers with the ionene archetype–presenting polymers with alternating functional and ionic elements precisely sequenced along the backbone. The effects of polymer composition on the thermal properties and morphology were analyzed. Five distinct polymer backbones were synthesized and combined with a stoichiometric equivalent of the IL 1-benzyl-3-methylimidazolium bistriflimide ([Bnmim][Tf2N]), which were studied to probe the self-assembly, structuring, and contributions of intermolecular forces when IL is added. Furthermore, three polyamide (PA) or polyimide (PI) ionenes with simpler xylyl linkages were interfaced with [Bnmim][Tf2N] as well as a novel amide-linked tris(imidazolium) IL, to demonstrate the structural changes imparted by the inclusion of functional, ionic additives dispersed within the ionene matrix. This work highlights the possibilities for utilizing concepts from small molecules which exhibit supramolecular self-assembly to guide creative design and manipulate the structuring of ionenes.
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Dissertations / Theses on the topic "Polymer backbone"

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Pollino, Joel Matthew. "The "Universal Polymer Backbone" concept." Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-11112004-143714/unrestricted/pollino%5Fjoel%5Fm%5F200412%5Fphd.pdf.pdf.

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Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2005.
Weck, Marcus, Committee Chair ; Jones, Christopher, Committee Member ; Collard, David, Committee Member ; Liotta, Charles, Committee Member ; Bunz, Uwe, Committee Member. Includes bibliographical references.
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Daglen, Bevin Colleen 1977. "Factors affecting the photodegradation rates of polymers that contain (cyclopentadienyl-(carbon monoxide)-molybdenum) in the backbone." Thesis, University of Oregon, 2008. http://hdl.handle.net/1794/8567.

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xxii, 143 p. ; ill. (some col.) A print copy of this title is available through the UO Libraries. Search the library catalog for the location and call number.
There are compelling economic and environmental reasons for using degradable plastics in selected applications and considerable research is now devoted to devising new photodegradable polymers with improved performance. Controlling the degradation of these materials in a prescribed fashion is still a difficult problem because the parameters that influence degradation rates are not completely understood. In order to predict polymer lifetimes, to manipulate when a polymer starts to degrade, and to control the rate of degradation, it is necessary to identify the experimental parameters that affect polymer degradation rates and to understand how these parameters affect degradation. This dissertation describes the results of experiments designed to gain fundamental insight into the factors that affect the rate of polymer photodegradation. The key experimental strategy employed was the incorporation of organometallic dimers into the backbone of the polymer chains, specifically, [CpRMo(CO) 3 ] 2 (CpR = a substituted cyclopentadienyl (· 5 -C 5 H 4 R)). Incorporating these organometallic units into a polymer chain make the polymer photodegradable because the metal-metal bond can be cleaved with visible light. The photogenerated metal radicals can then be trapped by O 2 or chlorine, resulting in degradation of the polymer. Another benefit from incorporating this chromophore into the polymer backbone is that it provides the experimentalist with a convenient spectroscopic handle to monitor degradation rates. Using these model polymers, several experimental factors that can affect polymer photodegradation rates have been explored. For example, experiments showed that radical trap concentration affects degradation rates below, but not above, the polymer glass transition temperature. In addition, degradation rates as a function of irradiation temperature, tensile stress, and time-dependent morphology changes were explored for various polymers. The results of these studies suggest that the ability of the photogenerated radicals to escape the radical cage is the dominant factor in determining photodegradation efficiencies. This dissertation includes previously published and unpublished co-authored material.
Adviser: David R. Tyler
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Farooq, Fauzia. "The stereoselective synthesis of side-chain liquid crystalline poly(ethyleneoxide)s possessing backbone chirality." Thesis, University of Hull, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343153.

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ANDREOSSO, IVAN. "FUNCTIONALIZATION OF UNSATURATED POLYMERS BACKBONE FOR TYRE COMPOUNDING APPLICATION." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2019. http://hdl.handle.net/10281/241275.

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Una delle principali applicazioni in cui i polimeri elastomerici trovano impiego è come componente strutturale nella formulazione di mescole per pneumatici. Tuttavia, affinché il prodotto finale possa soddisfare gli standard di prestazione richiesti, è necessario introdurre nella matrice polimerica dei componenti (filler) inorganici (Silice e Carbon Black). Sotto questo profilo, la compatibilità tra la fase polimerica e inorganica è dunque un aspetto di cruciale importanza. In questo contesto si colloca il presente progetto di dottorato, che ha come obiettivo quello di sviluppare un’innovativa strategia per migliorare il composito finale attraverso l’introduzione di gruppi funzionali sulla matrice polimerica in grado di interagire con le componenti inorganiche presenti in una mescola. Come prima cosa sono state scandagliate le opportunità che la letteratura offriva per trovare una reattività in grado di interessare i legami insaturi presenti nella matrice polimerica. In particolare, sono state identificate tre possibili alternative:cicloaddizione 1,3-dipolare, reazioni di tipo Tiol-Ene e reazioni di tipo Alder-Ene. Dopo aver verificato pregi e difetti di ciascuna reattività, la più promettente si è rivelata essere quella basata su una reazione di tipo Alder-Ene, che prevede l’interazione tra un’olefina, recante idrogeni in posizione allilica, ed un enofilo elettron-povero. Il composto enofilo da noi utilizzato e studiato come sistema modello è stato il 4-phenyl-1,2,4-triazoline-3,5-dione (PhTAD). Questo sistema, una volta ancorato sul polimero, presenta un gruppo ammidico secondario libero, in grado di modificare localmente la polarità della matrice e, contemporaneamente, di interagire tramite legami ad idrogeno con i filler inorganici come la silice. L’attività di ricerca è stata dunque concentrata sulla modifica chimica, con PhTAD, di olefine commerciali. Tali polimeri modificati, con diverse quantità di funzionalizzante, sono stati quindi caratterizzati tramite un approccio multitecnica (DSC, TGA, FTIR e prove di swelling) ed in seguito introdotti in mescola. Le proprietà reologiche delle mescole ottenute sono state valutate sia con un reometro a disco oscillante (ODR) sia tramite analisi dinamico meccaniche a temperatura variabile (DMTA) ed analizzandone le curve di stress-strain. Si è quindi tentato di risolvere le criticità emerse nell’utilizzo di PhTAD come agente di funzionalizzazione. Innanzitutto, è stato necessario ottimizzarne la quantità introdotta in mescola arrivando, nel migliore dei casi, ad ottenere compositi in cui i valori di G’ fossero comparabili con gli standard di rifermento industriali, che si basano sull’utilizzo di agenti compatibilizzanti come il TESPT, con un contestuale leggero peggioramento dei valori come il tanδ o l’effetto Payne, indice di un’effettiva interazione tra la matrice polimerica funzionalizzata con le cariche di silice, seppur non ottimale. Inoltre, uno dei maggiori problemi intrinseci da risolvere nell’utilizzo di una molecola come il PhTAD, risiede nella sua alta reattività che rende impossibile operare in massa, direttamente sul polimero pristino. L’ultima parte del progetto è stata quindi dedicata alla sintesi di funzionalizzanti di natura simile, a base diazenica, ma meno reattivi, allo scopo di far avvenire la reazione sul polimero direttamente in fase di formulazione, alle temperature a cui vengono processate le mescole (≈140°C), svincolandosi così dalla difficoltà derivanti dell’operare in soluzione. In particolare,l’avvenuta funzionalizzazione di un sistema oligomerico modello con ethyl(anilinocarbonyl)diazenecarboxylate ha permesso di dimostrare la validità dell’idea di una funzionalizzazione in massa termicamente stimolata, aprendo alla possibilità di impiego di altri sistemi molecolari, modificabili appositamente per assolvere una funzione specifica all’interno della mescola.
One of the main applications in which elastomeric polymers are used is as a structural component in the formulation of tire compounds. However, to match the required performance standards for the final product, it is necessary to introduce inorganic components (fillers) (Silica and Carbon Black) into the polymer matrix. From this point of view, the compatibility between the polymeric and inorganic phases is, therefore, an aspect of crucial importance. In this context the present PhD project is set up, which aims to develop an innovative strategy to improve the final composite through the introduction of functional groups on the polymer matrix able to interact with the inorganic components present in a compound. First, the opportunities offered by the literature to find a reactivity able to affect the unsaturated bonds present in the polymer matrix were explored. In particular, three possible alternatives have been identified: 1) 1,3-dipolar cycloaddition 2) Tiol-Ene type reactions 3) Alder-Ene type reactions After having verified the strengths and weaknesses of each reactivity, the most promising one has been to be based on an Alder-Ene reaction, which involves the interaction between an olefin (bearing hydrogen in an allyl position) and an electron-poor enophile. The enophilic compound we studied as a model system was 4-phenyl-1,2,4-triazoline-3,5-dione (PhTAD). This system, once anchored on the polymer, has a secondary amide group, able to modify locally the polarity of the matrix and, at the same time, able to interact through hydrogen bonds with inorganic fillers such as silica. The research activity has been focused on the chemical modification, with PhTAD, of commercial unsaturated polymers. These modified polymers, with different amounts of functionalizer, were then characterized by a multitechnical approach (DSC, TGA, FT-IR and swelling tests) and subsequently introduced into the mixture. The rheological properties of the compounds obtained were evaluated both with an oscillating disk rheometer (ODR), and by dynamic mechanical analysis at variable temperatures (DMTA) and by analyzing stress-strain curves. Preliminary attempts have been performed to resolve the critical issues that emerged when using PhTAD as a functionalization agent. First, it was necessary to optimize the amount introduced into the mixture, arriving, at best, to obtain composites in which the values of the G' module were comparable with the industrial reference standards, which are based on the use of compatibilizing agents such as TESPT, with a slight contextual deterioration of the values such as tanδ or the Payne effect, indicating an effective interaction between the polymer matrix functionalized with silica fillers, even if not yet optimally. Moreover, one of the major intrinsic problems to be solved in the use of a molecule such as PhTAD lies in its high reactivity which makes it impossible to operate in bulk, directly on the pristine polymer. The last part of the project was then dedicated to the synthesis of functionalizers of a similar nature, based on diazenics, but less reactive, in order to make the reaction occur on the polymer directly in the formulation phase, at the temperatures normally used to process compounds (≈140 °C), thus avoiding the difficulty due to operating in solution. The successful functionalization of a model oligomeric system with ethyl (anilinocarbonyl) diazenecarboxylate has allowed to demonstrate the validity of the idea of a thermally stimulated mass functionalization, opening to the possibility of using other molecular systems, that can be tuned specifically to perform a specific function within the compound.
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Kub, Christopher. "Hyperbranched conjugated polymers: an investigation into the synthesis, properties and postfunctionalization of hyperbranched poly(phenylene vinylene-phenylene ethynylene)s." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34838.

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There are two general ways to introduce functionalities into a polymeric structure: functionalization of the monomeric units before polymerization and postfunctionalization of the preformed polymer. Building libraries of polymers with different functionalities can be completed with significantly less effort by the second method, as each postfunctionalization of a single batch of polymeric backbone can involve as little as one synthetic step. One method of building a polymeric backbone for postfunctionalization involves the synthesis of hyperbranched conjugated polymers (HCPs) from AB2 monomeric units. A polymer formed from n AB2 monomeric units should contain n reactive B groups, which act as sites of functionalization. Utilizing this principle, two different hyperbranched poly(phenylene vinylene-phenylene ethynylene) scaffolds were synthesized and studied in both their inherent properties and functionalization. The first HCP synthesized was compared against a monomeric cruciform model and a linear polymer with a similar structure. The hyperbranched polymer has red-shifted absorption and emission in comparison to the cruciform model and linear polymer. The HCP quenches paraquat more efficiently than the linear polymer by a factor of about two, suggesting a greater rate of energy transfer. The functionalization of HCPs was studied; iodine groups decorating the HCPs were replaced with terminal alkynes by Pd-catalyzed coupling, providing a library of 24 differently functionalized HCPs. Elemental analyses of the postfunctionalized polymers show nearly complete substitution of the iodine groups. The postfunctionalized polymers show increased fluorescence compared to the original iodine decorated polymers, due to the loss of the heavy atom effect inducing iodine groups. The emissions of the postfunctionalized polymers in solution show a strong dependence on the groups attached to the conjugated structures, with emission maxima ranging from 505 nm to 602 nm; quantum yields range from 0.7% to 25%. Solid-state emission studies show stronger and more red-shifted spectra compared to emissions observed in solution.
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Gikonyo, Barnabas Kimaru. "Silicon backbone polymers as nerve growth substrates : an odyssey /." Available to subscribers only, 2007. http://proquest.umi.com/pqdweb?did=1481666341&sid=3&Fmt=2&clientId=1509&RQT=309&VName=PQD.

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Thesis (Ph. D.)--Southern Illinois University Carbondale, 2007.
"Department of Chemistry and Biochemistry." Keywords: Polysilane, Silicon backbone polymers, PC-12 cell growth, Nerve cell growth, Fibronectin, Polymers, Nerve growth substrates. Includes bibliographical references (p. 131-142). Also available online.
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Nur, Yusuf. "Electrochemical Polymerization Of Trihaloalkane Monomers To Form Branched C-backbone Polymers." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613168/index.pdf.

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Polycarbynes ( poly(hydridocarbyne), poly(methylcarbyne) and poly(phenylcarbyne) ) are a class of network polymers which are primarily composed of tetrahedrally hybridizated carbon atoms which have hydrogen, methyl or phenyl pendant group linked via three carbon-carbon single bonds to form a three dimensional network of fixed rings. This backbone oers unusual properties on the polymer including thermal decomposition to form diamond and diamondlike carbon. In this thesis, polycarbynes were synthesized by electrolytical reduction of trihaloorganocompounds, namely chloroform, hexachloroethane, 1,1,1-trichloroethane and 1,1,1-trichlorotoluene. Poly(hydridocarbyne) was synthesized using chloroform and hexachloroethane. Poly(methylcarbyne) was synthesized from 1,1,1-trichloroethane. Poly(phenylcarbyne) was synthesized from 1,1,1-trichlorotoluene. Polycarbynes were characterized by UV/Vis spectroscopy, 1H and 13C NMR spectroscopy, FTIR and GPC. All results are found to be consistent with literature
and thus a single step cheap, safe and easy method was introduced to scientists and manufacturers in diamond science. The resulting polymers were heated upon 1000oC under nitrogen atmosphere for 24 hours yielding in the formation of diamond and diamond-like carbon. Results indicated that both diamond films and powders were successfully produced from polycarbynes. Diamonds formed from the polymers were characterized via optical microscope, SEM, X-ray and Raman spectroscopy. All results shown in thesis are completely consistent with studies previously done for polycarbynes and diamond.
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Rust, Tarik [Verfasser]. "Stimuli-Responsive Backbone-Degradable (Co-)Polymers for Drug Delivery / Tarik Rust." Paderborn : Universitätsbibliothek, 2021. http://d-nb.info/1237748437/34.

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Okerio, Jaspher Mosomi. "Synthesis of fluorescent polymers with coumarin backbones by "click" polymerization." Thesis, Nelson Mandela Metropolitan University, 2013. http://hdl.handle.net/10948/d1020132.

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Click chemistry is one of the growing areas of research which is applied in the design and synthesis of a wide range of polymeric architectures. This investigation focuses on the synthesis of fluorescent coumarin based polymers by “click” A-B step growth polymerization process and evaluation of their photophysical properties. Non-fluorescent azide-alkyne functionalized coumarin-based monomers were synthesized in multiple steps from 2,4-dihydroxybenzaldehyde in reasonable yields. Polymers with coumarin backbone were synthesized from azide-alkyne functionalized coumarin monomers via the Cu(I) catalyzed 1,3-dipolar cycloaddition reaction between azides and alkynes, a typical click reaction, to form polymers whose repeating units are connected by a 1,2,3-triazole ring. The structures of the synthesized polymers were confirmed by NMR and FT-IR spectroscopy. Finally, the photophysical properties of the synthesized monomers and polymers were evaluated in DMF. All coumarin based monomers showed reduced fluorescent properties due to the quenching effect from the azido group. Although all polymers absorbed at maximum wavelength of 340 nm, a characteristic for coumarin chromophore, the homo-polymers emitted at a shorter wavelength of 413 nm as compared to the co-polymers which emitted at 421 nm.
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Babur, Tamoor [Verfasser]. "Structure and relaxation dynamics of comb-like polymers with rigid backbone / Tamoor Babur." Halle, 2017. http://d-nb.info/1139253743/34.

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Books on the topic "Polymer backbone"

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L, St Clair Terry, and Langley Research Center, eds. LARC-IA: A flexible backbone polyimide. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1990.

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L, St Clair Terry, and Langley Research Center, eds. LARC-IA: A flexible backbone polyimide. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1990.

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L, St Clair Terry, and Langley Research Center, eds. LARC-IA: A flexible backbone polyimide. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1990.

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Mark, James E., Dale W. Schaefer, and Gui Lin. The Polysiloxanes. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780195181739.001.0001.

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Polysiloxanes are the most studied inorganic and semi-inorganic polymers because of their many medical and commercial uses. The Si-O backbone endows polysiloxanes with intriguing properties: the strength of the Si-O bond imparts considerable thermal stability, and the nature of the bonding imparts low surface free energy. Prostheses, artificial organs, objects for facial reconstruction, vitreous substitutes in the eyes, and tubing take advantage of the stability and pliability of polysiloxanes. Artificial skin, contact lenses, and drug delivery systems utilize their high permeability. Such biomedical applications have led to biocompatibility studies on the interactions of polysiloxanes with proteins, and there has been interest in modifying these materials to improve their suitability for general biomedical application. Polysiloxanes examines novel aspects of polysiloxane science and engineering, including properties, work in progress, and important unsolved problems. The volume, with ten comprehensive chapters, examines the history, preparation and analysis, synthesis, characterization, and applications of these polymeric materials.
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Book chapters on the topic "Polymer backbone"

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Wohlfarth, Ch. "Second virial coefficient of polyphenylene (5 backbone phenylene rings per repeat unit)." In Polymer Solutions, 1045–71. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-02890-8_655.

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Yang, Jiyuan, and Jindřich Kopeček. "Backbone Degradable and Coiled-Coil Based Macromolecular Therapeutics." In Bioinspired and Biomimetic Polymer Systems for Drug and Gene Delivery, 1–28. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2014. http://dx.doi.org/10.1002/9783527672752.ch1.

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Tyler, David R., Jeffrey J. Wolcott, Gregory F. Nieckarz, and Steve C. Tenhaeff. "New Class of Photochemically Reactive Polymers Containing Metal—Metal Bonds Along the Polymer Backbone." In ACS Symposium Series, 481–96. Washington, DC: American Chemical Society, 1994. http://dx.doi.org/10.1021/bk-1994-0572.ch036.

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Pugh, Coleen, and Virgil Percec. "Effect of the Polymer Backbone on the Thermotropic Behavior of Side-Chain Liquid Crystalline Polymers." In ACS Symposium Series, 97–118. Washington, DC: American Chemical Society, 1988. http://dx.doi.org/10.1021/bk-1988-0364.ch008.

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Kim, Myoung-Hee, Jun Lee, Myong-Shik Cho, and Hee-Gweon Woo. "High Functional Inorganic Polymers Containing Main Group 13 – 16 Elements in the Polymer Backbone Chain." In Advanced Functional Materials, 65–101. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-19077-3_3.

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Aydin, Omer, Dilek Kanarya, Ummugulsum Yilmaz, and Cansu Ümran Tunç. "Determination of Optimum Ratio of Cationic Polymers and Small Interfering RNA with Agarose Gel Retardation Assay." In Methods in Molecular Biology, 117–28. New York, NY: Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-2010-6_7.

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AbstractNanomaterials have aroused attention in the recent years for their high potential for gene delivery applications. Most of the nanoformulations used in gene delivery are positively charged to carry negatively charged oligonucleotides. However, excessive positively charged carriers are cytotoxic. Therefore, the complexed oligonucleotide/nanoparticles should be well-examined before the application. In that manner, agarose gel electrophoresis, which is a basic method utilized for separation, identification, and purification of nucleic acid molecules because of its poriferous nature, is one of the strategies to determine the most efficient complexation rate. When the electric field is applied, RNA fragments can migrate through anode due to the negatively charged phosphate backbone. Because RNA has a uniform mass/charge ratio, RNA molecules run in agarose gel proportional according to their size and molecular weight. In this chapter, the determination of complexation efficiency between cationic polymer carriers and small interfering RNA (siRNA) cargos by using agarose gel electrophoresis is described. siRNA/cationic polymer carrier complexes are placed in an electric field and the charged molecules move through the counter-charged electrodes due to the phenomenon of electrostatic attraction. Nucleic acid cargos are loaded to cationic carriers via the electrostatic interaction between positively charged amine groups (N) of the carrier and negatively charged phosphate groups (P) of RNA. The N/P ratio determines the loading efficiency of the cationic polymer carrier. In here, the determination of N/P ratio, where the most efficient complexation occurs, by exposure to the electric field with a gel retardation assay is explained.
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Nabeshima, Y., Z. L. Ding, G. H. Chen, A. S. Hoffman, H. Taira, K. Kataoka, and T. Tsuruta. "Slow Release of Heparin from a Hydrogel Made from Polyamine Chains Grafted to a Temperature-Sensitive Polymer Backbone." In Advanced Biomaterials in Biomedical Engineering and Drug Delivery Systems, 315–16. Tokyo: Springer Japan, 1996. http://dx.doi.org/10.1007/978-4-431-65883-2_93.

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Wulff, Günter. "Optically Active Vinyl Polymers with Backbone Chirality." In Recent Advances in Mechanistic and Synthetic Aspects of Polymerization, 399–408. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-3989-9_32.

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Chivers, T. "S-Polymers with Organic Groups in the Backbone." In Inorganic Reactions and Methods, 180. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470145326.ch92.

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Lukeman, Philip. "Nucleic Acid Nanotechnology: Modified Backbones and Topological Polymer Templates." In DNA and RNA Nanobiotechnologies in Medicine: Diagnosis and Treatment of Diseases, 225–40. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-662-45775-7_9.

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Conference papers on the topic "Polymer backbone"

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Herman, W. N., J. A. Cline, J. M. Hoover, A. Chafin, G. A. Lindsay, and K. J. Wynne. "Nonlinear Optical Properties of Self-Assembled Mainchain Polymer Films." In Organic Thin Films for Photonic Applications. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/otfa.1995.md.28.

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We report second harmonic generation measurements on multilayers of two interleaved mainchain polymers fabricated by Langmuir Blodgett (LB) deposition. LB processing1 offers advantages over electric-field poling in that it can be done at room temperature (hence the kT Brownian motion is much less) without the strong electric fields that can lead to film damage during corona poling. Mainchain polymers are inherently more stable than sidechain polymers because both ends of the chromophore are attached to the backbone of the polymer, whereas only one end of the chromophore is attached to the backbone in a sidechain polymer, and the other end is dangling free at one of the interfaces of each monolayer. Furthermore, only mainchain polymers that contain the chromophore in a head-to-head (syndioregic) configuration can have the chromophores ordered normal to the plane of the film by hydrophilic/hydrophobic forces. This is because a mainchain polymer containing chromophores in a heat-to-tail configuration will probably have all of the chromophores lying on the water, in the plane of the film with opposing dominant hyperpolarizability components.
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Schellenberg, F. M., R. L. Byer, and R. D. Miller. "Substituted polysilanes for integrated optics." In Integrated Photonics Research. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/ipr.1990.mf5.

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Linear polysilanes are polymers consisting of a long catenated silicon backbone, with two side groups, usually carbon based, attached to each Si atom in the backbone chain. Electronic and structural properties can vary significantly with the side group, but common to all polysilanes is a degree of electron delocalization along the σ-bonded backbone. This delocalization results in large oscillator strengths for excitations polarized parallel to the backbone. Absorption of UV photons decays either by UV fluorescence or scission of the polymer backbone, making these materials useful as deep UV photoresists for microlithography. These large oscillator strengths also give rise to large optical nonlinear susceptibilities.
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Tsustumi, Naoto, Osamu Matsumoto, Wataru Sakai, and Tsuyoshi Kiyotsukuri. "Novel Nonlinear Optical Polymers for Second Harmonic Generation." In Organic Thin Films for Photonic Applications. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/otfa.1995.md.5.

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Recently, we have synthesized a new type of NLO phore whose dipole moment is aligned transverse to the main chain backbone, and resultant poled polymer film shows large second harmonic efficiency with its good thermal stability. In this paper, we present the second harmonic generation (SHG) properties of this novel type of NLO polymer material whose dipole moment is aligned transverse to the main chain backbone and compare these properties to those for the polymer with NLO phore in the main chain backbone.
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Bannaron, Alisa, Andrew Mark Spring, and Shiyoshi Yokoyama. "Electro-optic (EO) polymer with highly thermal stable norbornene-based polymer backbone (Conference Presentation)." In Organic Photonic Materials and Devices XXI, edited by Christopher E. Tabor, François Kajzar, and Toshikuni Kaino. SPIE, 2019. http://dx.doi.org/10.1117/12.2508328.

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Soares, João A., and Paolo Zunino. "A Multiscale Mixture Model for Polymer Degradation and Erosion." In ASME 2010 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/sbc2010-19251.

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Over the last 50 years, biodegradable materials have found a wide variety of applications in the medical field ranging from biodegradable sutures, pins and screws for orthopedic surgery, implants for local drug delivery, tissue engineering scaffolds, and biodegradable endovascular and urethral stents. The ability to predict the evolution of biodegradable polymers over the course of degradation would enhance the biodegradable implant design process. Polymer degradation is the irreversible chain scission process that breaks polymer chains down to oligomers and finally monomers. Extensive degradation leads to erosion, which is the process of material loss from the polymer bulk. Such materials can be monomers, oligomers, parts of the polymer backbone, or even parts of the polymer bulk. Hence, degradation and erosion are distinct but related process.
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Teng, C. C., D. R. Haas, H. T. Man, and H. N. Yoon. "Guided-Wave Polymeric Electro-Optic Modulators." In Integrated and Guided Wave Optics. Washington, D.C.: Optica Publishing Group, 1988. http://dx.doi.org/10.1364/igwo.1988.wd7.

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Organic materials have shown promise as second order nonlinear materials1; however, device demonstrations have been lacking. This has been largely due to the difficulty of growing noncentrosymmetric crystals out of the polar organic molecules and lack of suitable waveguide fabrication techniques for these materials. We have approached this problem by using polymers where the nonlinear (NLO) moiety is attached to a polymer backbone as a pendant side chain2. Using the polymeric materials, we have fabricated and tested planar waveguide modulators. Linear waveguides have also been fabricated with these polymers and are being developed into phase and polarization rotation modulators.
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Akle, Barbar J., Mike Hickner, Donald J. Leo, and James E. McGrath. "Electroactive Polymers Based on Novel Ionomers." In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-43561.

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A majority of research on ionic polymer transducers has used Nafion™ as the base material. Varying the physical and chemical properties of Nafion is difficult, which limits the understanding and development of ionic transducers. In this study we investigate a novel class of polymers called BPSH (sulfonated poly(arylene ether sulfone)s). The polymers are synthesized by the direct polymerization of sulfonated monomers. This synthetic scheme affords precise control of the amount and the location of ionic groups along the polymar backbone. These polymers differ from Nafion™ in two major ways. First, the concentration of ionic groups on a mass basis is almost double that of standard Nafion™, 1.51 meq/g for BPSH-30 versus 0.91 meq/g for Nafion™ 1100. Also, the backbone of the BPSH copolymers is much stiffer than Nafion, which affords a higher modulus material. Both of these factors, ion content and modulus, are expected to affect the performance of polymer-based actuators. Another ionomer characterized is the PATS (poly(arylene thiother sulfone)s) which is similar to BPSH. For both polymers we are varying the ionic concentration, stiffness, and water content. Those variations are fostering the understanding of operating concepts of ionic transducers, especially the correlation between ionic transducers, especially the correlation between ionic concentration and performance. Experiments on BPSH-35 demonstrate improved performance as compared to Nafion™ They provide larger strain per unit volt, larger force generated, and larger bandwidth. The novel polymers are characterized as sensors and actuators.
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Venugopal, Vinithra, Hao Zhang, and Vishnu-Baba Sundaresan. "A Chemo-Mechanical Constitutive Model for Conducting Polymers." In ASME 2013 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/smasis2013-3218.

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Conducting polymers undergo volumetric expansion through redox-mediated ion exchange with its electrolytic environment. The ion transport processes resulting from an applied electrical field controls the conformational relaxation in conducting polymer and regulates the generated stress and strain. In the last two decades, significant contributions from various groups have resulted in methods to fabricate, model and characterize the mechanical response of conducting polymer actuators in bending mode. An alternating electrical field applied to the polymer electrolyte interface produces the mechanical response in the polymer. The electrical energy applied to the polymer is used by the electrochemical reaction in the polymer backbone, for ion transport at the electrolyte-polymer interface and for conformational changes to the polymer. Due to the advances in polymer synthesis, there are multitudes of polymer-dopant combinations used to design an actuator. Over the last decade, polypyrrole (PPy) has evolved to be the most common conducting polymer actuator. Thin sheets of polymer are electrodeposited on to a substrate, doped with dodecylbezenesulfonate (DBS-) and microfabricated into a hermetic, air operated cantilever actuator. The electrical energy applied across the thickness of the polymer is expended by the electrochemical interactions at the polymer-electrolyte interface, ion transport and electrostatic interactions of the backbone. The widely adopted model for designing actuators is the electrochemically stimulated conformational relaxation (ESCR) model. Despite these advances, there have been very few investigations into the development of a constitutive model for conducting polymers that represent the input-output relation for chemoelectromechanical energy conversion. On one hand, dynamic models of conducting polymers use multiphysics-based non-linear models that are computationally intensive and not scalable for complicated geometries. On the other, empirical models that represent the chemomechanical coupling in conducting polymers present an over-simplified approach and lack the scientific rigor in predicting the mechanical response. In order to address these limitations and to develop a constitutive model for conducting polymers, its coupled chemomechanical response and material degradation with time, we have developed a constitutive model for polypyrrole-based conducting polymer actuator. The constitutive model is applied to a micron-scale conducting polymer actuator and coupling coefficients are expressed using a mechanistic representation of coupling in polypyrrole (dodecylbenzenesulfonate) [PPy(DBS)].
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Tsutsumi, Naoto, Osamu Matsumoto, and Wataru Sakai. "Orientational Relaxation of NLO Dipole Moments Transversely Aligned to the Main Backbone in the Linear Polyurethane." In Organic Thin Films for Photonic Applications. Washington, D.C.: Optica Publishing Group, 1997. http://dx.doi.org/10.1364/otfa.1997.the.5.

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Recently, we have synthesized a new type of linear polyurethane (T-polymer) with NLO azobenzene chromophore whose dipole moment is aligned transverse to the main chain backbone and another linear urethane polymer (L-polymer) with NLO dipole chromophore incorporated in the main chain backbone.1 The resultant poled T-polymer shows the large second order nonlinearity of d33=1.6 × 10-7 esu (67 pm/V) with good thermal stability at the ambient conditions.1 This polymer is amorphous with a high density of NLO chromophore moiety and optically transparent thin film, which can be processed by spin-casting or solvent casting.
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Gipson, Kyle G., Philip J. Brown, Kathryn A. Stevens, and Christopher L. Cox. "Properties, Characterization and Fiber Extrusion Simulation of Novel Amorphous Polymers for Optical Application." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11544.

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Polymeric optical fibers are generally manufactured in the same manner as traditional glass (silica) fibers. As technology advances, more efficient, cost effective materials and processes are being developed to serve the duties of optical materials within networks. Traditional polymer optical fibers are comprised of hydrocarbon amorphous polymers and include polymethyl methacrylate (PMMA) and polystyrene (PS). These types of polymers have inherent issues in optical applications such as their signal absorption loss. This is largely due to the vibration of the carbon-hydrogen (C-H) bond contained in the polymer backbone. Therefore, to broaden the scope of polymer optical fibers, novel exotic amorphous polymers are being developed. One such polymer family, reported to have excellent optical properties, is perfluorocyclobutyl aryl ethers (PFCB), which do not exhibit the strong C-H vibrations associated with absorption loss. At this time, little is known of the intrinsic properties of PFCBs as well as the behavior of the polymer melt during extrusion. This work will review the thermal and rheological properties of two PFCB polymers: biphenylvinyl ether (BPVE) and hexafluoroisopropylidene vinyl ether (6F). The information gathered from the analysis of these two intrinsic properties will be used as the input data for a fiber extrusion simulation model, FiSim. The application of the FiSim software was done in order to produce a viable limited range of process conditions for which fibers could be melt spun.
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Reports on the topic "Polymer backbone"

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Percec, Virgil, Dimitris Tomazos, and Reginal A. Willingham. The Influence of the Polymer Backbone Flexibility on the Phase Transitions of Side Chain Liquid Crystal Polymers Containing 6-(4-Methoxy-Beta-Metylstyryl) Phenoxy)Hexyl Side Groups. Fort Belvoir, VA: Defense Technical Information Center, May 1989. http://dx.doi.org/10.21236/ada208821.

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Matyjaszewski, Krzysztof. Catalysts and Initiators as Instruments Controlling Structure of Polymers with Inorganic Backbone. Fort Belvoir, VA: Defense Technical Information Center, May 1991. http://dx.doi.org/10.21236/ada235350.

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Carpita, Nicholas C., Ruth Ben-Arie, and Amnon Lers. Pectin Cross-Linking Dynamics and Wall Softening during Fruit Ripening. United States Department of Agriculture, July 2002. http://dx.doi.org/10.32747/2002.7585197.bard.

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Our study was designed to elucidate the chemical determinants of pectin cross-linking in developing fruits of apple and peach and to evaluate the role of breakage cross-linkages in swelling, softening, and cell separation during the ripening. Peaches cell walls soften and swell considerably during the ripening, whereas apples fruit cells maintain wall firmness but cells separate during late stages of ripening. We used a "double-reduction" technique to show that levels of non-methyl esters of polyuronic acid molecules were constant during the development and ripening and decreased only in overripe fruit. In peach, methyl and non-methyl esters increased during the development and decreased markedly during the ripening. Non-methyl ester linkages in both fruit decreased accompanied fruit softening. The identity of the second component of the linkage and its definitive role in the fruit softening remain elusive. In preliminary examination of isolated apples cell walls, we found that phenolic compounds accumulate early in wall development but decrease markedly during ripening. Quantitative texture analysis was used to correlate with changes to wall chemistry from the fresh-picked ripe stage to the stage during storage when the cell separation occurs. Cell wall composition is similar in all cultivars, with arabinose as the principal neutral sugar. Extensive de-branching of these highly branched arabinans pre-stages softening and cell-cell separation during over-ripening of apple. The longer 5-arabinans remain attached to the major pectic polymer rhamnogalacturonan I (RG I) backbone. The degree of RG I branching, as judged from the ratios of 2-Rha:2,4-Rha, also decreases, specially after an extensive arabinan de-branching. Loss of the 4-Rham linkages correlated strongly with the softening of the fruit. Loss of the monomer or polymer linked to the RG I produce directly or indirectly the softening of the fruit. This result will help to understand the fruit softening and to have better control of the textural changes in fruit during the ripening and especially during the storage. 'Wooliness', an undesirable mealy texture that is induced during chilling of some peach cultivars, greatly reduces the fruit storage possibilities. In order to examine the hypothesis that the basis for this disorder is related to abnormality in the cell wall softening process we have carried out a comparative analysis using the resistant cultivar, Sunsnow, and a sensitive one, Hermosa. We investigated the activity of several pectin- and glycan-modifying enzymes and the expression of their genes during ripening, chilling, and subsequent shelf-life. The changes in carbohydrate status and in methyl vs. non-methyl uronate ester levels in the walls of these cultivars were examined as well to provide a basis for comparison of the relevant gene expression that may impact appearance of the wooly character. The activities of the specific polygalacturonase (PGase) and a CMC-cellulase activities are significantly elevated in walls of peaches that have become wooly. Cellulase activities correlated well with increased level of the transcript, but differential expression of PGase did not correspond with the observed pattern of mRNA accumulation. When expression of ethylene biosynthesis related genes was followed no significant differences in ACC synthase gene expression was observed in the wooly fruit while the normal activation of the ACC oxidase was partially repressed in the Hermosa wooly fruits. Normal ripening-related loss of the uronic acid-rich polymers was stalled in the wooly Hermosa inconsistent with the observed elevation in a specific PGase activity but consistent with PG gene expression. In general, analysis of the level of total esterification, degree of methyl esterification and level of non-methyl esters did not reveal any major alterations between the different fruit varieties or between normal and abnormal ripening. Some decrease in the level of uronic acids methyl esterification was observed for both Hermosa and Sunsnow undergoing ripening following storage at low temperature but not in fruits ripening after harvest. Our results support a role for imbalanced cell wall degradation as a basis for the chilling disorder. While these results do not support a role for the imbalance between PG and pectin methyl esterase (PME) activities as the basis for the disorder they suggest a possible role for imbalance between cellulose and other cell wall polymer degradation during the softening process.
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