Literatura académica sobre el tema "Development of Polymers"

The green and versatile character of deep eutectic solvents (DES) has turned them into significant tools in the development of green and sustainable technologies. For this purpose, their use in polymeric applications has been growing and expanding to new areas of development. The present review aims to summarize the progress in the field of DES applied to polymer science and engineering. It comprises fundamentals studies involving DES and polymers, recent applications of DES in polymer synthesis, extraction and modification, and the early developments on the formulation of DES–polymer products. The combination of DES and polymers is highly promising in the development of new and ‘greener’ materials. Still, there is plenty of room for future research in this field.

Due to the thermal and fire sensitivity of polymer bio-composite materials, especially in the case of plant-based fillers applied for them, next to intensive research on the better mechanical performance of composites, it is extremely important to improve their reaction to fire. This is necessary due to the current widespread practical use of bio-based composites. The first part of this work relates to an overview of the most commonly used techniques and different approaches towards the increasing the fire resistance of petrochemical-based polymeric materials. The next few sections present commonly used methods of reducing the flammability of polymers and characterize the most frequently used compounds. It is highlighted that despite adverse health effects in animals and humans, some of mentioned fire retardants (such as halogenated organic derivatives e.g., hexabromocyclododecane, polybrominated diphenyl ether) are unfortunately also still in use, even for bio-composite materials. The most recent studies related to the development of the flame retardation of polymeric materials are then summarized. Particular attention is paid to the issue of flame retardation of bio-based polymer composites and the specifics of reducing the flammability of these materials. Strategies for retarding composites are discussed on examples of particular bio-polymers (such as: polylactide, polyhydroxyalkanoates or polyamide-11), as well as polymers obtained on the basis of natural raw materials (e.g., bio-based polyurethanes or bio-based epoxies). The advantages and disadvantages of these strategies, as well as the flame retardants used in them, are highlighted.

This review article describes the current status and recent advances of polymeric drugs with regard to their application in drug delivery system. Essentially polymer-drug conjugation aims to achieve improved drug targeting, decrease drug toxicity and overcome mechanisms of drug resistance. First generation conjugates used linear monomethoxy PEGs and other linear polymers. Modern polymeric chemistry is increasingly producing new polymeric architectures such as dendrimers, hyper branched polymers and hybrid macromolecular structures (such as star polymers, linear graft and dendronized linear polymers and novel therapeutic siRNA. This undoubtedly can be employed for designing of second generation polymer therapeutics. Clinical approval of products such as Copaxone®, Renagel®, Vivagel® and Welchol® have been successful in developing interest in polymer therapeutics as a growing field of research and development. In conclusion, there is emerging data that polymer drug conjugation has become useful in a wide range of treatments from infectious to chronic diseases such as cancer. Polymer therapeutics holds promising future applications in the field of nanotherapeutics. Polymeric Drugs: A Novel Approach to Drug Delivery System

(1) Different methods have been applied to fabricate polymeric membranes with non-solvent induced phase separation (NIPS) being one of the mostly widely used. In NIPS, a solvent or solvent blend is required to dissolve a polymer or polymer blend. N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF) and other petroleum-derived solvents are commonly used to dissolve some petroleum-based polymers. However, these components may have negative impacts on the environment and human health. Therefore, using greener and less toxic components is of great interest for increasing membrane fabrication sustainability. The chemical structure of membranes is not affected by the use of different solvents, polymers, or by the differences in fabrication scale. On the other hand, membrane pore structures and surface roughness can change due to differences in diffusion rates associated with different solvents/co-solvents diffusing into the non-solvent and with differences in evaporation time. (2) Therefore, in this review, solvents and polymers involved in the manufacturing process of membranes are proposed to be replaced by greener/less toxic alternatives. The methods and feasibility of scaling up green polymeric membrane manufacturing are also examined.

Benzo[1,2-d:4,5-d′]bis(oxazole) (BBO) is a heterocyclic aromatic ring composed of one benzene ring and two oxazole rings, which has unique advantages on the facile synthesis without any column chromatography purification, high solubility on the common organic solvents and planar fused aromatic ring structure. However, BBO conjugated building block has rarely been used to develop conjugated polymers for organic thin film transistors (OTFTs). Three BBO-based monomers, BBO without π-spacer, BBO with non-alkylated thiophene π-spacer and BBO with alkylated thiophene π-spacer, were newly synthesized and they were copolymerized with a strong electron-donating cyclopentadithiophene conjugated building block to give three p-type BBO-based polymers. The polymer containing non-alkylated thiophene π-spacer showed the highest hole mobility of 2.2 × 10−2 cm2 V−1 s−1, which was 100 times higher than the other polymers. From the 2D grazing incidence X-ray diffraction data and simulated polymeric structures, we found that the intercalation of alkyl side chains on the polymer backbones was crucial to determine the intermolecular ordering in the film states, and the introduction of non-alkylated thiophene π-spacer to polymer backbone was the most effective to promote the intercalation of alkyl side chains in the film states and hole mobility in the devices.

The purpose of writing this review on floating drug delivery systems (FDDS) was to compile the recent literature with special focus on the principal mechanism of floatation to achieve gastric retention . This can be achieved by use of various polymeric substances including natural polymers. These polymers are inexpensive, safe and available in a variety of structures with versatile characteristics. Large number of derivatizable groups, wide range of molecular weights, varying chemical composition gel forming nature of these polymers also provide an exciting opportunities in the fascinating arena of applied polymer science and drug delivery technology. All these characteristics make them suitable candidate for design and fabrication of novel gastroretentive drug delivery systems. Various natural polymers have been investigated worldwide by scientific community for their potential as floating drug delivery systems. The present article highlights various recent efforts and advanced approaches exploiting several natural polymers in this technology. DOI: http://dx.doi.org/10.3329/ijpls.v2i4.17116 International Journal of Pharmaceutical and Life Sciences Volume 2, Issue 4: October 2013; 165-178

In this review we present polymeric materials for (bio)sensor technology development. We focused on conductive polymers (conjugated microporous polymer, polymer gels), composites, molecularly imprinted polymers and their influence on the design and fabrication of bio(sensors), which in the future could act as lab-on-a-chip (LOC) devices. LOC instruments enable us to perform a wide range of analysis away from the stationary laboratory. Characterized polymeric species represent promising candidates in biosensor or sensor technology for LOC development, not only for manufacturing these devices, but also as a surface for biologically active materials’ immobilization. The presence of biological compounds can improve the sensitivity and selectivity of analytical tools, which in the case of medical diagnostics is extremely important. The described materials are biocompatible, cost-effective, flexible and are an excellent platform for the anchoring of specific compounds.

Natural gas is the most rapid growing energy sources around the world. The presence of CO2 in natural gas lowers its calorific value and purification of a natural gas by removing CO2 is an essential process to increase its value. Several separation technologies are used to remove acidic gases like H2S and CO2 from natural gas. Among these technologies, membrane process is a feasible energy saving alternate to CO2 capture. The three types of membrane include polymeric, inorganic and mixed matrix membranes. Currently, polymer membranes and inorganic membranes were considered for gas separation, but inorganic membranes are too costly. Even mixed matrix membrane performance suffered defects caused by poor glassy polymer and particle interactions. Pure glassy and pure rubbery are problematic due to their instructive properties. The blending of glassy with rubbery polymers improve membrane properties for gas separation. To enhance the compatibility of the polymer blend, a third component is added such as alkanol amines. Although, the enhanced polymeric blend membranes have many advantages in terms of permeance, selectivity, thermal and chemical stability. Polymer blending also offers an effective technique to synthesize membranes with desirable properties.

Natural gas is the most rapid growing energy sources around the world. The presence of CO2 in natural gas lowers its calorific value and purification of a natural gas by removing CO2 is an essential process to increase its value. Several separation technologies are used to remove acidic gases like H2S and CO2 from natural gas. Among these technologies, membrane process is a feasible energy saving alternate to CO2 capture. The three types of membrane include polymeric, inorganic and mixed matrix membranes. Currently, polymer membranes and inorganic membranes were considered for gas separation, but inorganic membranes are too costly. Even mixed matrix membrane performance suffered defects caused by poor glassy polymer and particle interactions. Pure glassy and pure rubbery are problematic due to their instructive properties. The blending of glassy with rubbery polymers improve membrane properties for gas separation. To enhance the compatibility of the polymer blend, a third component is added such as alkanol amines. Although, the enhanced polymeric blend membranes have many advantages in terms of permeance, selectivity, thermal and chemical stability. Polymer blending also offers an effective technique to synthesize membranes with desirable properties.

Polymer electrolytes continue to offer the opportunity for safer, high-performing next-generation battery technology. The benefits of a polymeric electrolyte system lie in its ease of processing and flexibility, while ion transport and mechanical strength have been highlighted for improvement. This report discusses how factors, specifically the chemistry and structure of the polymers, have driven the progression of these materials from the early days of PEO. The introduction of ionic polymers has led to advances in ionic conductivity while the use of block copolymers has also increased the mechanical properties and provided more flexibility in solid polymer electrolyte development. The combination of these two, ionic block copolymer materials, are still in their early stages but offer exciting possibilities for the future of this field.

Thesis (MSc)--Stellenbosch University, 2002.
ENGLISH ABSTRACT: Multimedia was the buzzword of the previous decade. Electronic learning is the buzzword of this decade. Both concepts changed, and are still changing the way educators present knowledge and information to students, both locally and worldwide. South Africa, also standing in the midst of these technological changes, has its own unique opportunities regarding the teaching environment. Different factors are currently changing the educational scene in South Africa. With Curriculum 2000 and the Outcome-Based Education concept (OBE) came the opportunity to choose and incorporate relevant science and technology programmes into school curriculums. The introduction of Technology as a subject in junior secondary school, opened the door to bring students in contact with, for example, the vast world of material science. Senior secondary students, on the contrary, have little or no exposure to teaching programmes on modern materials; materials that rule their lives! There is a need for high quality, easily accessible and informative material science programmes. This provided the initiative to create this programme. Depending on the standard of students, "Fun with Polymers" can be used as: • a lecturing tool for teachers and lecturers • an encyclopeadia which students can interactively navigate to learn more about polymer science • a source of information to anyone curious about the interesting world of plastic materials. The name "Fun with Polymers" indicates that learning science can be fun (after ali!). The programme contains easy to use navigation buttons, helpfiles, hypertext, sound, animations and pictures to teach synthetic polymer material science. Content consists of the history of the development of polymer materials, basic polymer chemistry principles, information on the building of macromolecules, facts on synthetic polymer materials, and some questions and answers to test the student's knowledge. Practical experiments, with plastic materials, complement the theoretical information and provide students with hands-on experience.
AFRIKAANSE OPSOMMING: Multimedia was die gonswoord van die vorige dekade. Elektroniese leer is die gonswoord van die nuwe dekade. Beide hierdie konsepte het, en is nog steeds besig, om die wyse hoe kennis en inligting, plaaslik en wêreldwyd, aan studente oorgedra word, te verander. Suid-Afrika, as deel van hierdie tegnologiese veranderinge, bied unieke en uitdagende geleenthede op die gebied van onderwys. Verskillende faktore beïnvloed, op die oomblik, die plaaslike onderwys scenario. Die koms van Kurrikulum 2000 en Uitkomsgebaseerde Onderwys het die deur vir toepaslike wetenskap- en tegnologie programme, as deel van skoolleerplanne, geopen. Die toevoeging van Tegnologie, as vakgebied, tot die junior sekondêre fase, skep die geleentheid om studente in aanraking te bring met, byvoorbeeld, die enorme wêreld van materiaalkunde. Senior sekondêre studente het egter min tot geen blootstelling aan materiaalkunde leerprogramme ten spyte van die feit dat hul lewens daagliks deur moderne materiale beïnvloed en beheer word! Daar bestaan 'n behoefte aan hoë kwaliteit, maklik bekombare inligting oor moderne materiale en vandaar die dryfveer om hierdie program te skep. Afhangende van die standaard van die studente, kan hierdie program gebruik word as: • 'n onderrigprogram vir onderwysers en lektore • 'n bron van inligting wat studente interaktief kan navigeer om meer van polimeeerchemie te wete te kom • 'n bron van inligting vir enigiemand wat nuuskierig is oor die interessante wêreld van plastieke. Die naam van hierdie program: "Fun with Polymers" dui daarop dat die wetenskapleerproses pret kan wees! Die program bestaan uit maklik navigeerbare instruksies, hulplêers, hiperteks, klank, animasies, en foto's om lig te werp op die onderwerp van plastiek. Die inhoud beslaan die geskiedenis van die ontwikkeling van plastiek= materiale, basiese polimeerchemie beginsels, inligting oor die vorming van makro= molekules, feite oor sintetiese polimeermateriale, en vrae en antwoorde om die gebruiker te toets oor sy/haar kennis. Maklik uitvoerbare en toepaslike praktiese eksperimente komplimenteer die teoretiese inhoud van die multimedia program.

Kyoto University (京都大学)
0048
新制・課程博士
博士(工学)
甲第14643号
工博第3111号
新制||工||1463(附属図書館)
26995
UT51-2009-D355
京都大学大学院工学研究科高分子化学専攻
(主査)教授 澤本 光男, 教授 伊藤 紳三郎, 教授 辻 康之
学位規則第4条第1項該当

Comme je suis particulièrement intéressé par les nanosciences et les nombreuses applications des nanotechnologies, je me suis penché sur le développement de méthodes de fabrication de nanoparticules ultra-petites dont les fonctions peuvent être ajustées avec précision. Récemment, une nouvelle technologie appelée « technologie d’une seule chaîne », c’est-à-dire qui utilise une seule chaîne polymère, est devenue un sujet de recherche de plus en plus motivant pour la communauté scientifique. Cette technologie a l’avantage de dépendre d’une méthode facile de préparation de nanoparticules polymères d’une seule chaîne (SCNPs) et ayant des dimensions typiques de 1,5 à 20 nm. Leurs tailles ultra petites leur confèrent des propriétés spécifiques, ce qui permet de les utiliser comme capteurs, systèmes catalytiques, revêtements à faible viscosité, nanoréacteurs ou pour des applications biomédicales. Grâce aux contributions de nombreux scientifiques durant la dernière décennie, les méthodes de synthèse des SCNPs sont devenues très variées et représentent une technologie désormais mature. Néanmoins, de nombreux problèmes sont à résoudre dans ce domaine, ce qui permettra d’ajouter de nouvelles fonctions ou de les valoriser pour de nouvelles applications. Les polymères sensibles à plusieurs stimuli sont une classe de matériaux intelligents dont les propriétés peuvent être modifiées par l’application d’un stimulus extérieur. Ils sont utilisés extensivement dans les domaines énergétique et biomédical. Comme leurs propriétés physiques et chimiques peuvent être modifiées aisément et efficacement par un contrôle de leur environnement externe, ces polymères sont des candidats pour fabriquer de nouvelles SCNPs. Dans cette thèse, nous nous sommes intéressés au développement de SCNPs ayant de multiples fonctionnalités car cela permet d’ouvrir la voie pour de nouvelles applications. Pour cela, de nombreux polymères sensibles à plusieurs stimuli ont été préparés comme précurseurs à des SCNPs. En concevant spécifiquement ces polymères, il fut possible d’ajouter leurs propriétés de réponse à des stimuli dans les systèmes SCNPs. Le cœur même de cette thèse consiste en trois projets qui utilisèrent trois classes de SCNPs provenant de polymères sensibles aux stimuli. Grâce à leur réponse à plusieurs stimuli, ces SCNPs remplirent de nombreuses fonctions et subirent des modifications soit de leur structure, soit de leur morphologie, soit de leurs propriétés. Et en plus de la variété de fonctions, chaque classe de SCNPs a le potentiel pour de nombreuses applications. Dans la première étude présentée dans cette thèse (chapitre 1), nous avons préparé une classe de SCNPs photodégradables ayant une taille ajustable et inférieure à 10 nm. Il s’agit de polyesters rendus photosensibles par la présence de coumarines à l’intérieur de la chaîne principale (nommés CAPPG) grâce à la copolymérisation de coumarine diol, d’acide adipique et de propylène glycol (PPG). Cette incorporation de coumarines dans la chaîne principale permet au polymère d’être photosensible par deux façons. En effet, les coumarines peuvent se photo-dimériser, lorsqu’elles sont irradiées par des rayonnements UV (> 320 nm) en des cyclobutanes qui peuvent être ouverts à nouveau par d’autres rayonnements UV (254 nm) permettant la restauration des coumarines initiales. Cela a permis la création de SCNPs de tailles inférieures à 10 nm et incluant des propriétés de photodégradation. Cette propriété a été démontrée par une irradiation de 3 h avec des chaînes polymères de 13220 g/mol à 1385 g/mol dans les SCNPs. La taille de ces SNCPs (caractérisée par leur rayon hydrodynamique) peut être modifiée entre 3 nm et 5,3 nm en modifiant le taux de dimérisation des coumarines, ce qui est aisément obtenu en ajustant le temps d’irradiation UV. Les résultats ont démontré que cette méthode permet un contrôle aisé de la taille des SCNPs sans avoir recours à la synthèse de nombreux polymères précurseurs. Finalement, comme le polyester était biodégradable et biocompatible, ces SCNPs peuvent être exploitées pour des applications biomédicales. Dans la deuxième étude effectuée au cours de cette thèse (chapitre 2), nous avons préparé un nouveau type de SCNPs multifonctionnel à partir d’un polymère cristallin liquide. Il s’agit du polyméthacrylate de [2- (7-méthylcoumaryl) oxyéthyle - co - 6-[4-(4’-méthoxyphenylazo) phénoxy] hexyle] (PAzoMACMA). Les groupements latéraux du polymère contiennent, en majorité, des azobenzènes photoisomérisables et, en minorité, des coumarines photodimérisables. Les azobenzènes servent de mésogènes pour la formation de cristaux liquides alors que les coumarines ont été utilisées pour une réticulation photoinduite et intrachaîne. Malgré les dimensions inférieures à 15 nm, le confinement et la réticulation, les phases cristallines liquides (LC) persistèrent même dans les SCNPs. Ces SCNPs cristaux liquides (LC-SCNPs) présentèrent un certain nombre de propriétés intéressantes et particulières. Alors que leurs dispersions dans le THF n’étaient pas fluorescentes, celles dans le chloroforme l’étaient. En plus, ces nanoparticules s’aggloméraient quelque peu dans le chloroforme ce qui induisait des fluorescences différentes entre des SCNPs riches en isomères cis ou riches en isomères trans des azobenzènes. A cause de la photoisomérisation des azobenzènes, ces LC-SCNPs se déformaient sous irradiation comme le font les microparticules ou les colloïdes contenant des azobenzènes. Cependant, la déformation de ces nanoparticules dépend de la longueur d’onde de lumière polarisée. Alors que sous irradiation UV polarisée à 365 nm, l’élongation des SCNPs était perpendiculaire à la polarisation de la lumière incidente, sous irradiation visible polarisée entre 400 et 500 nm, l’étirement se faisait parallèlement à la polarisation. Finalement, un nanocomposite fut préparé par dispersion de LC-SCNPs dans une matrice de polyméthacrylate de méthyle (PMMA). Si celui-ci était étiré mécaniquement, les azobenzènes s’orientaient dans la direction de la déformation induite. Ces propriétés intéressantes des LC-SCNPs que cette étude a permis de dévoiler, suggèrent de nouvelles applications potentielles. Dans la troisième étude de cette thèse (chapitre 3), nous avons préparé une classe de SCNPs sensibles à la présence de CO2 et leurs agrégats micellaires auto-assemblés. D’un côté, des SCNPs ont été préparées à partir d’un polyméthacrylate de {(N, N-diméthylaminoéthyle)-co-4-méthyl-[7-(méthacryloyl)-oxyéthyl-oxy] coumaryle} (PDMAEMA-co-CMA). Lorsqu’elles sont dispersées en solution aqueuse, les nanoparticules individuelles peuvent subir des cycles réversibles d’expansion et de rétrécissement sous une stimulation alternative de CO2 et de N2 qui vont protoner et déprotoner les amines tertiaires. D’un autre côté, des SCNPs de type ‘Janus’ (SCJNPs) ont été préparées à partir d’un copolymère dibloc amphiphile : PS-b-P(DMAEMA-co-CMA) (PS correspond au polystyrène qui est hydrophobe). Ce type de SCJNPs peut s’autoassembler sous forme de micelles en solution aqueuse. Sous stimulation CO2 ou N2, l’expansion ou le rétrécissement à l’intérieur des particules permet de grands changements de volume. En plus, ces particules ont été étudiées comme potentiels nanoréacteurs pour des nanoparticules d’or (AuNPs) que ce soit sous formes SCNPs ou micelles SCJNPs. La vitesse de formation des AuNPs augmente sous bullage de CO2 et décroît sous N2. Cela permet de rendre possible cette réaction contrôlable par ces deux gaz. Qui plus est, utiliser des micelles de SCJNPs dont le volume peut être modifié sur un large intervalle en changeant l’intensité de la stimulation de CO2, permit d’obtenir des AuNPs de taille variable.
Abstract : With interests on nanoscience and nanotechnology for many applications, there is a demand for development of fabrication technology of ultra-small nano-size objects that allow for precise size control and tailored functionality. Recently, a new technology called ‘single-chain technology’, which manipulates a single polymer chain, becomes a rapidly-growing research topic. This technology provides a facile method to prepare polymer single-chain nanoparticles (SCNPs) with a typical size of 1.5-20 nm. Due to the ultra-small size-enabled unique properties, SCNPs have wide range of applications, including sensor, catalytic system, low viscosity coating, nanoreactor and biomedical applications. Through the contributions by many scientists in the past decade, the synthetic methodologies to fabricate SCNPs have been reported using various chemistries and been getting mature. However, there are still several unsolved problems in the field of SCNPs including functions and application. Stimuli-responsive polymers, as a class of smart materials whose properties can be changed by responding to external stimuli, have been widely used in energy and biomedical applications. Since their chemical and physical properties can be changed easily and efficiently via environmental control, stimuli-responsive polymers provide a potential pathway to preparing functional SCNPs. In this thesis, we are focusing on developing functional SCNPs, especially systems with multi-functions, and expanding their applications. To achieve this target, various stimuli-responsive polymers were prepared as polymer precursors and their stimuli-responsive properties were introduced into the SCNP systems by rational design of their chemical structures. The core of this thesis is comprised of three projects which deal with three classes of SCNPs from stimuli-responsive polymers. These stimuli-responsive SCNPs perform multi-functions and undergo certain change either in structure or morphology and properties. In addition, according to their variety of functions, each class of multi-functional SCNPs has diverse potential applications. In the first study presented in the thesis (Chapter 1), we prepared a class of sub-10 nm photodegradable and size-tunable SCNPs based on photo-responsive main-chain coumarin-based polyesters Poly{[7-(hydroxypropoxy)-4-(hydroxymethyl)coumarin adipate]-co- (polypropylene glycol adipate)} (CAPPG) through copolymerization of coumarin diol, adipic acid and polypropylene glycol (PPG). By incorporating coumarin moieties into the chain backbone of a polyester, dual photo-responsive reaction, i.e. photo-dimerization (>320 nm) and photo-induced chain scission (254 nm), occur under two different wavelengths of UV irradiation, enabling the preparation of sub-10 nm SCNPs and their photo-degradation property. The photo-degradability of SCNPs is evidenced under 254 nm UV irradiation for 3 h, which molecular weight of SCNPs decreasing from 13220 g/mol to 1385 g/mol. Moreover, the size of SCNPs can be tunable from 5.3 nm to 3 nm (hydrodynamic diameter) by varying the dimerization degree of coumarin moieties, that is simply controlled by the UV irradiation time. These results demonstrate a facile method to control the size of SCNPs without the need for synthesizing different polymer precursors. Finally, due to the biocompatible and biodegradable nature of polyester as polymer precursor, the SCNPs with photo-degradability and size-tunability have the potential to be exploited for biomedical applications. In the second study realized in this thesis (Chapter 2), we prepared a new type of multi-functional SCNPs from a side-chain liquid crystalline polymer (SCLCP), namely poly{6-[4-(4-methoxyphenylazo) phenoxy]hexylmethacrylate-co-4-methyl-[7-(methacr-yloyl) oxy-ethyl-oxy]coumarin} (PAzoMACMA). The polymer’s side groups comprise photo-isomerizable azobenzene in majority and photo-dimerizable coumarin in minority, with the former as mesogens and the latter for intra-chain photo-crosslinking. Despite the sub-15 nm size, confinement and crosslinking, the liquid crystalline (LC) phases of bulk PAzoMACMA persist in SCLCPs. Such LC-SCNPs exhibit a number of interesting and peculiar properties. While their dispersion in THF is non-fluorescent, when dispersed in chloroform, the nanoparticles appear to agglomerate to certain degree and display significant fluorescence that is different for SCNPs rich in the trans or cis isomer of azobenzene. The azobenzene LC-SCNPs also undergo photo-induced deformation, similar to azobenzene micro- or colloidal particles. However, the elongational deformation of the nanoparticles is dependent upon the linearly polarized excitation wavelength. While under polarized 365 nm UV irradiation the SCNP stretching direction is perpendicular to the light polarization, under polarized 400-500 nm visible light irradiation, the stretching takes place along the light polarization direction. Finally, an all-polymer nanocomposite was prepared by dispersing the LC-SCNPs in poly(methyl methacrylate) (PMMA), and mechanically stretching-induced orientation of azobenzene mesogens developed along the strain direction. The interesting properties of LC-SCNPs unveiled in this study suggest new possibilities for applications including bio-imaging and LC materials. As the third study in this thesis (Chapter 3), we studied a class of CO2-responsive SCNPs and their self-assembled micellar aggregates. On one hand, SCNPs are prepared from a random copolymer of poly{(N,N-dimethylaminoethyl methacrylate)-co-4-methyl-[7-(methacryloyl)oxyethyl-oxy]coumarin} (P(DMAEMA-co-CMA)). When dispersed in aqueous solution, individual nanoparticles can undergo reversible swelling/shrinking under alternating CO2/N2 stimulation as a result of the reversible protonation/deprotonation of tertiary amine groups. On the other hand, tadpole-like single-chain ‘Janus’ nanoparticles (SCJNPs) are prepared using an amphiphilic diblock copolymer of PS-b-P(DMAEMA-co-CMA) (PS is hydrophobic polystyrene). This type of SCJNPs can self-assemble into core-shell micellar aggregates in aqueous solution. Under CO2/N2 stimulation, the collective swelling/shrinking of SCJNPs within the micelle results in large, reversible volume change. In addition, both P(DMAEMA-co-CMA) SCNPs and PS-b-P(DMAEMA-co-CMA) SCJNP micelles are explored as gas-tunable nanoreactors for gold nanoparticles (AuNPs). The rate of AuNP formation increases under CO2 stimulation and decreases upon N2 bubbling, which makes it possible to tune the reaction rate up and down (on/off switching) by using the two gases. Moreover, using the micelles of SCJNPs, whose volume can be controlled over a wide range by adjusting the CO2 stimulation strength, variable-size AuNPs and their aggregates are obtained with continuous redshift of the surface plasmon resonance (SPR) into the long wavelength visible light region.

A series of eight novel bidentate ligands, designed for use in the construction of nickel-selective molecularly imprinted polymers (MIP's), have been prepared. The synthetic pathway was established by retrosynthetic analysis of the target molecules to the readily available precursors, pyridine-2-carbaldehyde (or 6-methylpyridine-2-carbaldehyde) and ethyl bromoacetate. The ligands were designed to contain an allyl group for co-polymerisation and amine and pyridyl nitrogen donors, located to permit the formation of 5-membered nickel chelates. The eight novel ligands and their respective precursors were characterized by elemental (high-resolution MS) and spectroscopic (IR and ¹H and ¹³C NMR) analysis. High resolution electron-impact mass spectrometry has also been used, together with B/E linked scan data, to explore the fragmentation patterns of selected ligands. The various nickel(ll) complexes were analyzed using spectroscopic techniques and, in some cases, elemental analysis; computer modelling has also been used to explore conformational effects and complex stability. Numerous MIP's, containing nickel(II) complexes of the bidentate ligands, have been prepared, using ethylene glycol dimethylacrylate (EGDMA) as the cross-linker, azobis(isobutyronitrile) (AlBN) as the polymerization initiator and MeOH as the porogenic solvent. The template nickel(II) ions were leached out with conc. HCI, and the nickel(II) selectivity [in the presence of Fe(Ill)] of the nickel-imprinted polymers was examined by ICP-MS analysis. The ICP-MS data indicate that the MIP's examined exhibit extremely high selectivity for nickel over iron.
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Age-related macular degeneration (AMD) is the largest cause of blindness for those over 65 in the developed world. There is currently no treatment for the retinal cellular loss associated with the disease. One potential therapy is to implant retinal stem cells into the eye using a biodegradable polymer scaffold. Blends of the biodegradable polymers, poly(L-lactic acid) (PLLA) and poly(D,L-lactic-co-glycolic acid) (PLGA) have been formulated into microspheres. The influence of changing processing parameters on the size and morphology of the microspheres has been studied. A human retinal pigment epithelial (APRE-19) cell line was shown to adhere, survive and proliferate on the surface of the microspheres in vitro. Assays have demonstrated that the nature of the blend influenced cell behaviour. Transplantation of retinal pigment epithelial (RPE) cells on a supportive matrix has also been investigated as a therapy for AMD. In view of AMD related pathology of the native RPE support, Bruch’s membrane (BM), transplanted RPE cells require a scaffold to reside on. Copolymers based on methyl methacrylate (MMA) and poly(ethylene glycol) methacrylate (PEGM) have been synthesised and chemically modified at the PEG terminus. These polymers were subsequently manufactured into a fibrous scaffold using an electrospinning technique and investigated as an artificial BM. RPE cells were shown to attach and proliferate successfully on the surface of the fibrous scaffold in vitro. Cell adhesion was significantly enhanced on scaffolds with the PEG chain terminus modification. Significantly less apoptotic cell death was also observed on these surfaces. The diffusion properties of these artificial membranes have also been investigated. In addition, the novel gelation of the produced copolymers under certain conditions has been studied

Polymeric materials have several favorable properties for heat transfer systems, including low weight, low manufacturing cost, antifouling, and anticorrosion. Additionally, polymers are typically electrical insulators, making them favorable for applications in which electrical conductivity is a concern. Examples of utilizing these favorable properties are discussed. The drawbacks to raw polymer materials include low thermal conductivity, low structural strength, and poor stability at elevated temperatures. Methods of mitigating these unfavorable properties, including loading the polymer with other materials and developing new polymers, are discussed. Enhanced geometric designs enabled by additive manufacturing can also improve thermal performance of polymer heat exchangers. Results of a research study utilizing additive manufacturing toward developing high-performance and cost-effective polymer heat exchangers for an air-to-liquid application are reviewed and discussed. Finally, needs for further research on enhancing polymer thermal performance are discussed.

Abstract In this work, we present the development and deployment of high activity liquid polymer that improves logistics for field deployment in supply chain constrained locations. Such polymers show superior performance in terms of dissolution times, increased neat polymer stability, and improved injectivity during tertiary oil displacement in comparison to traditional emulsion polymers. The initial screening process comprised of testing for viscosity yields in the desired brine, filterability, and long term injectivity corefloods in surrogate rocks. Additional tests included long term aging studies with contaminants to measure shelf life of the neat polymer. Finally, yard scale tests were conducted to identify mixing configuration and system pressures for optimal mixing conditions to scale up for field deployment. The liquid polymer developed for this application shows superior performance with rapid viscosity yields both in lab scale and yard scale mixing tests. Long term injection shows good injectivity (stable pressure for greater than 25 PV injected). Aging tests demonstrated the improved shelf life and higher stability of the neat material in the presence of iron. Application of mechanical shear and imposing temperature vaiations to the neat polymer did not affect the quality of the diluted polymer solution. QA/QC of field supplied batches indicate consistent quality of commercial scale polymer production thus demonstrating the applicability of liquid polymer for piloting at the field scale. The developed liquid polymers improve upon the limitation of traditional emulsion polymers with higher activity, better injectivity, faster dissolution times and better neat polymer stability. These features combined lead to enhanced product performance thus further de-risking polymer flooding in logistically challenging environments.

In this article, the role and application of oligomers have been studied. The kinetics and thermodynamics of phase transitions in nanostructured systems during the formation of three-dimensional polyethoxysiloxane polymers were studied. The aim of the study was to study the rheokinetic patterns of the formation of three-dimensional polymer structures based on tetraethoxysilane by varying the catalyst content in the reaction system using the viscometric method. The rheokinetics of the sol-gel process for the production of polymer-silica sorbents was studied. The process of obtaining polymeric microspherical silica gel was studied.

Abstract The oil well cement placed in the annulus between casings and the formations experience high stresses under downhole conditions. These frequent stresses deteriorate the mechanical properties of cement and lead to the formation of micro-cracks and fractures, which affect production and increases the cost of operation. Although several polymeric materials have been employed to improve tensile properties of the cement, these additives have also adversely affected the compressive strength of the cement. A highly stable polymeric additive, triazine-based polymers, is designed, synthesized, and compounded with the cement to improve the tensile properties of the well-cement. Triazine polymer was characterized by fourier transform infrared spectroscopy and thermogravimetric analysis. The triazine polymer was mixed with cement and the cement slurries were cured at 180 °F under 3000 psi for 3 days. The set-cement samples were subjected to mechanical testing under high temperature and high pressure to study the elastic properties of the cement. The introduction of this polymer into the cement has improved the elastic properties of the cement with minimum reduction in compressive strength. The thickening time, dynamic compressive strength development, rheology, fluid loss properties, and brazilian tensile strength of the control and cement with triazine polymers were studied to understand the effect of this newly developed polymeric additive. The molecular interaction of the triazine polymer with cement particles has shown formation of covalent linkage between the polymer and cement particle. We have observed a 15 % decrease in Young's modulus for cement compounded with 2%wt. of triazine polymer, indicating the introduction of elastic properties in wellbore cement.

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.

In this 1-year feasibility study, we tried polymerization of several different monomers, commercial as well as novel, specially designed and synthesized for this project in the presence of the nitrate ion to produce imprinted conductive polymers. Polymers 1 and 2 (shown below) produced a response to nitrate, but one inferior to that produced by a polypyrrole (Ppy)-based sensor (which we demonstrated prior to this study). Thus, we elected to proceed with improving the stability of the Ppy-based sensor. In order to improve stability of the Ppy-based sensor, we created a two-layer design which includes nitrate-doped Ppy as an inner layer, and nitrate-doped PEDOT as the outer layer. PEDOT is known for its high environmental stability and conductivity. This design has demonstrated promise, but is still undergoing optimization and stability testing. Previously we had failed to create nitrate-doped PEDOT in the absence of a Ppy layer. Nitrate-doped PEDOT should be very promising for sensor applications due to its high stability and exceptional sensing properties as we showed previously for sensing of perchlorate ions (by perchlorate-doped PEDOT). During this year, we have succeeded in preparing nitrate-doped PEDOT (4 below) by designing a new starting monomer (compound 3 below) for polymerization. We are currently testing this design for nitrate sensing. In parallel with the fabrication design studies, we fabricated and tested nitrate-doped Ppy sensors in a series of flow studies under laboratory and field conditions. Nitrate-doped Ppy sensors are less stable than is desirable but provide excellent nitrate sensing characteristics for the short-term experiments focusing on packaging and deployment strategies. The fabricated sensors were successfully interfaced with a commercial battery-powered self-logging (Onset Computer Hobo Datalogger) and a wireless data acquisition and transmission system (Crossbow Technologies MDA300 sensor interface and Mica2 wireless mote). In a series of flow-through experiments with water, the nitrate-doped Ppy sensors were exposed to pulses of dissolved nitrate and compared favorably with an expensive commercial sensor. In 24-hour field tests in both Merced and in Palmdale, CA agricultural soils, the sensors responded to introduced nitrate pulses, but with different dynamics relative to the larger commercial sensors. These experiments are on-going but suggest a form factor (size, shape) effect of the sensor when deployed in a porous medium such as soil. To fill the need for a miniature reference electrode, we identified and tested one commercial version (Cypress Systems, ESA Mini-reference electrode) which works well but is expensive ($190). To create an inexpensive miniature reference electrode, we are exploring the use of AgCl-coated silver wire. This electrode is not a “true” reference electrode; however, it can calibrated once versus a commercial reference electrode at the time of deployment in soil. Thus, only one commercial reference electrode would suffice to support a multiple sensor deployment.

Two commercial superabsorbent polymer (SAP) formulations were used to internally cure cement pastes, mortars, and concretes with a range of water-to-cement ratios (w/c 0.35–0.52). The following properties were determined as a function of cement chemistry and type, use of chemical admixtures, use of slag, and batching parameters: SAP absorption capacity, fresh mixture workability and consistency, degree of hydration, volumetric stability, cracking tendency, compressive and flexural strength, and pumpability. SAP internal curing agents resulted in cementitious mixtures with improved hydration, accelerated strength gain, greater volumetric stability, and improved cracking resistance while maintaining sufficient workability to be pumped and placed without sacrificing compressive or flexural strength. When using SAP, batching adjustments prioritized the use of water reducing admixture instead of extra water to tune workability. While the benefits of SAP internal curing agents for low w/c mixtures were expected, SAP-containing mixtures with w/c ≥ 0.42 displayed accelerated strength development and decreased cracking tendency.