Добірка наукової літератури з теми "Poly(acrylate) networks"

Three aqueous self-assembling poly(acrylate) networks have been designed to gain insight into the factors controlling the complexation and release of small molecules within them. These networks are formed between 8.8% 6A-(2-aminoethyl)amino-6A-deoxy-6A-β-cyclodextrin, β-CDen, randomly substituted poly(acrylate), PAAβ-CDen, and one of the 3.3% 1-(2-aminoethyl)amidoadamantyl, ADen, 3.0% 1-(6-aminohexyl)amidoadamantyl, ADhn, or 2.9% 1-(12-aminododecyl)amidoadamantyl, ADddn, randomly substituted poly(acrylate)s, PAAADen, PAAADhn and PAAADddn, respectively, such that the ratio of β-CDen to adamantyl substituents is ca. 3:1. The variation of the characteristics of the complexation of the dyes methyl red, methyl orange and ethyl orange in these three networks and by β-cyclodextrin, β-CD, and PAAβ-CDen alone provides insight into the factors affecting dye complexation. The rates of release of the dyes through a dialysis membrane from the three aqueous networks show a high dependence on host–guest complexation between the β-CDen substituents and the dyes as well as the structure and the viscosity of the network as shown by ITC, 1H NMR and UV–vis spectroscopy, and rheological studies. Such networks potentially form a basis for the design of controlled drug release systems.

We experimentally measured the effect of nature and concentration of crosslinker on the photopolymerized time of the poly(hydroxy-butyl-methacrylate-co-2-ethyl-hexyl-acrylate)/5CB system. Initial mixtures are composed of monofunctional monomers hydroxy-butyl-methacrylate (HBMA) and 2-ethyl-hexyl-acrylate (2-EHA), and one of the three bifunctional monomers, poly-propylene-glycol-di-acrylate (PPGDA), tri-propylene-glycol-di-acrylate (TPGDA), or 1,6-hexane-diol-di-acrylate (HDDA), and 2-hydroxy-2-methylpropiophenone (Darocur 1173) as a photoinitiator. The copolymers were elaborated via UV irradiation of reactive formulation. The central composite face-centered design of experiments (DoE) has been used to determine the influence of temperature, crosslinking density and their interactions on swelling behavior of poly(HBMA-co-EHA/crosslinker) networks in liquid crystal 5CB. The experimental results and the predicted responses indicate a good correlation and therefore the validity of the used model.

A series of semi-I tpe interpenetrating polymer networks (IPN) based on poly chromium acrylate and poly acrylonitrile crosslinked with divinyl benzene have been synthesized. Synthetic details, including concentration of poly chromium acriylate (PCrA), acrylonitrile (AN) and divinyl benzene (DVB) and average molecular weight of PCrA were varied and their effect on the crosslink density of the network was studied by swelling experiments. High [PCrAJ and low [AN] increases swelling and thereby average molecular weight between crosslinks (M,). SEM micrographs and glass transition temperature show phase separation at high [PCrA] content.

碩士
大同大學
化學工程研究所
93
This article describes the synthesis of interpenetrating polymer networks (IPNs) based on Poly(ethylene glycol) methyl ether acrylate (PEGMEA) and gelatin，which were crosslinked sequentially using N,N’-methylene bisacrylamide (NMBA) and glutaraldehyde， respectively。 Various samples were prepared by taking varying amounts of PEGMEA and gelatin in the initial feed。 Sequential IPNs were prepared by first polymerizing and crosslinking PEGMEA in the presence of gelatin using redox initiators (Ammonium Peroxydisulfate and N,N,N'',N''''- tetramethylethylenediamine) and NMBA as a crosslinking agent。 Gelatin present in the firm gels was then crosslinked using 1% glutaraldehyde。 Characterization of these gels was done by measuring their swelling behavior， Mechanical Behavior，Drug Release Behavior， and Scanning election micrographs。

Polymer networks are promising biomaterials for drug delivery as they have porous structures and are often biocompatible. The general aspects of the host-guest complexation capability of polymer networks containing cyclodextrins as well as their application in drug delivery are considered in Chapter 1. The introduction of cyclodextrins into polymer networks has the potential to improve drug loading capacity and modulate subsequent drug release behavior due to the host-guest complexation by cyclodextrins of drug molecules. Thus, Chapter 2 and Chapter 3 are concerned with new research on water soluble β-cyclodextrin, adamantyl and octadecyl substituted poly(acrylate) networks, respectively, as potential sustained drug delivery systems. In Chapter 2, research into self-assembled poly(acrylate) networks cross-linked through host-guest complexation between β-cyclodextrin, β-CD, substituents and adamantyl, AD, substituents as potential sustained drug delivery systems is described. A poly(acrylate) (PAA) 8.8% randomly substituted with β-CD through an ethyl tether, PAAβ-CDen, is synthesized as a host poly(acrylate). Poly(acrylate)s 3.3%, 3.0% and 2.9% randomly substituted with AD substituents, respectively, through ethyl, hexyl and dodecyl tethers in the PAAADen, PAAADhn and PAAADddn are synthesized as guest polymers. The host-guest complexation of PAAADen, PAAADhn, and PAAADddn by PAAβ-CDen in aqueous solution produce three self-assembled poly(acrylate) networks. These complexations are characterized by isothermal titration calorimetry, ITC, 2D NOESY ¹H NMR spectroscopy, and rheology. It is found that the length of the tether between the AD group and the poly(acrylate) backbone has a substantial influence on the complexation constants, KITC [ITC subscript], as well as the associated enthalpy change, ΔH, and entropy change, ΔS. The smallest and largest KITC [ITC subscript] occur for PAAADen with the shortest tether and PAAADddn with the longest tether, which coincides with the lowest and highest viscosities occurring for the aqueous PAAβ-CDen/PAAADen and PAAβ-CDen/PAAADddn networks. The complexation of three different dye molecules, acting as drug models, by the β-CD substituents in these networks is characterized by UV-Vis spectroscopy and 2D NOESY ¹H NMR studies. The results suggest that dye complexation by the β-CD substituents in the three poly(acrylate) networks is weaker by comparison with the complexation by native β-CD and PAAβ-CDen, as indicated by decreased complexation constants. The poly(acrylate) networks exhibit complexation-controlled dye release behavior, and thereby sustained dye release profiles. Thus, the three poly(acrylate) networks studied, which form hydrogels at higher concentrations, have substantial potential as sustained drug delivery systems. In Chapter 3, the complexation and release behavior of six dyes in a β-CD- and octadecyl-substituted poly(acrylate) network is explored to further extend the understanding of the host-guest complexation between β-CD substituents and guest molecules within a fourth polymer network system and its influence on the release of guest molecules from the polymer network. Thus, β-CD substituents are 9.3% randomly substituted onto poly(acrylate) through an ethyl tether to give PAAβ-CDen and octadecyl, C18, substituents are 3.5% randomly substituted onto poly(acrylate) to give PAAC18. The network forms through the host-guest complexation between the β-CD substituents and C18 substituents, and is characterized by a complexation constant of K = 1.13 × 10⁴ dm³ mol⁻¹, associated with ΔH = −21.55 kJ mol⁻¹ and TΔS = 1.59 kJ mol⁻¹. The complexation of the dyes by the β-CD substituents in the PAAβ-CDen/PAAC18 network is characterized by UV-Vis absorption and fluorescence spectroscopy and 2D NOESY ¹H NMR studies. The results suggest that the complexation of dyes by the β-CD substituents in the PAAβ-CDen/PAAC18 network is weaker by comparison with the complexation by native β-CD and PAAβ-CDen, as indicated by decreased complexation constants. The PAAβ-CDen/PAAC18 network exhibits complexation-controlled dye release behavior and thereby sustained dye release profiles. Thus, the PAAβ-CDen/PAAC18 network, or hydrogel at higher concentration, is a potential sustained drug delivery system. Conjugated polymer nanoparticles are promising fluorescent probes as a consequence of their high brightness and photostability. Chapter 1 introduces the general methods of preparing conjugated polymer nanoparticles and their wide ranges of biological applications. However, conjugated polymer nanoparticles exhibit large-scale aggregation and precipitation at the high ionic strengths encountered under physiological conditions, which presents an impediment to their biological applications. In seeking to address this issue, the research described in Chapter 4 and Chapter 5 addresses stabilization of conjugated polymer nanoparticles using hydrophobic linear alkyl group substituted poly(acrylate)s and bovine serum albumin and explores their deployment in cell imaging applications. In Chapter 4, the synthesis of hydrophobic linear alkyl group substituted poly(acrylate)s, PAACn, is described as is their employment as conjugated polymer nanoparticle stabilizers. (When n = 18, 16 and 10 the alkyl groups are octadecyl, hexadecyl and decyl, respectively.) The carboxylate groups of PAACn increase the surface charge of the conjugated polymer nanoparticles and thereby stabilize them in phosphate buffered saline, PBS. Nanoparticles of the green-yellow emitting conjugated polymer, F8BT, stabilized with PAACn, F8BT-PAACn, are prepared using a nano-precipitation method. In contrast to the significant aggregation with a negligible yield (~ 0%) of bare F8BT nanoparticles in PBS, high yields approaching 90% are observed for F8BT nanoparticles stabilized with PAAC18 at 1%, PAAC16 at 3%, and PAAC10 at 10% substitution. The F8BT-PAACn nanoparticles have small sizes ranging from 50 to 70 nm in diameter, highly negative surface charge and high colloidal stability over 4 weeks in PBS. These properties pave the way for the deployment of F8BT-PAACn nanoparticles in biological applications. Spectroscopic results indicate the PAACn has no adverse effect on the UV-Vis absorptivity and fluorescence brightness of F8BT-PAACn nanoparticles relative to bare F8BT nanoparticles. In addition, F8BT-PAACn nanoparticles are internalized by HEK 293 cells and exhibit negligible cytotoxicity. Thus, PAACn are versatile and robust stabilizing materials that facilitate the application of F8BT-PAACn nanoparticles as fluorescent probes in cell imaging.The research described in Chapter 5 shows that bovine serum albumin, BSA, stabilizes conjugated polymer nanoparticles in phosphate buffered saline, PBS, evidently due to the combined effects of the negatively charged surfaces arising from the BSA carboxylate groups and the steric effect of the bulk 3D structure of BSA. Three multicolored conjugate polymers, PDOF, F8BT, and MEHPPV, are employed to prepare their corresponding nanoparticles using a nano-precipitation method. In contrast to the significant aggregation with negligible yields (~ 0%) of bare conjugated polymer nanoparticles occurring in PBS, high yields approaching 100% are observed for conjugated polymer nanoparticles stabilized with BSA, CP-BSA nanoparticles, in PBS. These CP-BSA nanoparticles have small sizes ranging from 20 to 60 nm, negative surface charges and high colloidal stability. Spectroscopic results indicate the BSA has no adverse effect on the UV-Vis absorptivity and fluorescence brightness of the CP-BSA nanoparticles relative to bare conjugated polymer nanoparticles. These properties potentially pave the way for the deployment of these CP-BSA nanoparticles in biological applications.
Thesis (Ph.D.) -- University of Adelaide, School of Physical Sciences, 2016.

碩士
長庚大學
化工與材料工程研究所
93
Interpenetrating network membranes of poly (2-hydroxylethyl meth- acrylate) (poly HEMA) and poly (vinyl alcohol) (PVA) in various ratios were prepared by UV radiation and treated with glutaraldehyde (GA). From the spectral change of FTIR, the hydroxyl groups disappeared and an acetal ring and ether linkage were formed for the reaction between the hydroxyl groups of PVA and GA. From the stress-strain curve, it was found that the tensile strength and elongation increased with PVA content on the PVA / poly (HEMA) membranes. After crosslinking with GA, the membranes became brittle, whereas the thermal stability increased about 20-100℃. Two glass transition temperature were found for the PVA / poly (HEMA) membranes. It means that PVA and poly (HEMA) are incompatible in this study. Due to the hydrophilicity of poly (HEMA), the water content in the membranes increased with increasing the content of poly (HEMA) in the membranes. After treatment with GA, the contact angle on the PVA / poly (HEMA) membranes decreased. The permeation of creatinine, 5-fluorouracil (5-FU) and vitamin B12 through at 37℃ were conducted. The permeability increased with increasing poly (HEMA) content in the membranes.

Random copolymers are prepared by the copolymerization of a mixture of cyclic oligomers. Although the resulting polymer can be quite blocky (figure 8.1), taking the reaction to equilibrium can give a polymer that is essentially random in its chemical sequencing. One reason for preparing copolymers is to introduce functional species, such as hydrogen or vinyl side groups, along the chain backbone to facilitate cross linking. Another reason is the introduction of sufficient chain irregularity to make the polymer inherently noncrystallizable. Specific examples of comonomers include imides, perylenediimide, urethane-ureas, epoxies, other siloxanes, amides, styrene, divinylbenzene, acrylics, silsesquioxanes, polythiophenes, and poly(lactic acid). One novel combination is the preparation of polysiloxanebased episulfide resins. An unusual application is the use of monomethylitaconate- grafted polymethylsiloxane to induce crystal growth of CaCO3. Polysiloxanes containing thermally curable brenzoxazine moieties in the main chain are also in the category. These and other copolymers have been extensively characterized by nuclear magnetic resonance (NMR) spectroscopy. The sequential coupling of functionally terminated chains of different chemical structure can be used to make block copolymers, including those in which one or more of the blocks is a polysiloxane. If the blocks are relatively long, separation into a two-phase system invariably occurs. Frequently, one block will be in a continuous phase and the other will be dispersed in domains having an average size the order of a few hundred angstroms. Such materials can have unique mechanical properties not available from homopolymer species. Sometimes similar properties can be obtained by the simple blending of two or more polymers. Examples of blocks used with polydimethylsiloxane (PDMS) include imides, epoxies, butadienes, ε-caprolactones, amides having trichlorogermyl pendant groups, urethanes, ureas, poly(ethylene glycols), polystyrene, vinyl acetates, acrylates or methacrylates, 2-vinylpyridine, and even other polysiloxanes. Some results have also been reported for polyesters, polyethers, hydroxyethers of bisphenol A, bisphenol A arylene ether sulfones, vinylpyridinebenzoxazines, methyloxazolines, terpyridines, polysulfones, γ-benzyl-Lglutamate, and carboranes. Two other examples are foamed polypropylene and melamine resins. Even ABA, ABC triblock copolymers, and ABCBA pentablock copolymers involving PDMS have been reported.