Academic literature on the topic 'Polyesters; Copolymers; Side chains'
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Journal articles on the topic "Polyesters; Copolymers; Side chains"
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Tarabukina, Elena, Emil Fatullaev, Anna Krasova, et al. "Synthesis, Structure, Hydrodynamics and Thermoresponsiveness of Graft Copolymer with Aromatic Polyester Backbone at Poly(2-isopropyl-2-oxazoline) Side Chains." Polymers 12, no. 11 (2020): 2643. http://dx.doi.org/10.3390/polym12112643.
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New thermoresponsive graft copolymers with an aromatic polyester backbone and poly(2-isopropyl-2-oxazoline) (PiPrOx) side chains are synthesized and characterized by NMR and GPC. The grafting density of side chains is 0.49. The molar masses of the graft-copolymer, its backbone, side chains, and the modeling poly-2-isopropyl-2-oxaziline are 74,000, 19,000, 4300, and 16,600 g·mol−1, respectively. Their conformational properties in nitropropane as well as thermoresponsiveness in aqueous solutions are studied and compared with that of free side chains, i.e., linear PiPrOx with a hydrophobic terminal group. In nitropropane, the graft-copolymer adopts conformation of a 13-arm star with a core of a collapsed main chain and a PiPrOx corona. Similarly, a linear PiPrOx chain protects its bulky terminal group by wrapping around it in a selective solvent. In aqueous solutions at low temperatures, graft copolymers form aggregates due to interaction of hydrophobic backbones, which contrasts to molecular solutions of the model linear PiPrOx. The lower critical solution temperature (LCST) for the graft copolymer is around 20 °C. The phase separation temperatures of the copolymer solution were lower than that of the linear chain counterpart, decreasing with concentration for both polymers.
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Kupczak, Maria, Anna Mielańczyk, and Dorota Neugebauer. "The Influence of Polymer Composition on the Hydrolytic and Enzymatic Degradation of Polyesters and Their Block Copolymers with PDMAEMA." Materials 14, no. 13 (2021): 3636. http://dx.doi.org/10.3390/ma14133636.
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Well-defined, semi-degradable polyester/polymethacrylate block copolymers, based on ε-caprolactone (CL), d,l-lactide (DLLA), glycolide (GA) and N,N′-dimethylaminoethyl methacrylate (DMAEMA), were synthesized by ring-opening polymerization (ROP) and atom transfer radical polymerization. Comprehensive degradation studies of poly(ε-caprolactone)-block-poly(N,N′-dimethylaminoethyl methacrylate) (PCL-b-PDMAEMA) on hydrolytic degradation and enzymatic degradation were performed, and those results were compared with the corresponding aliphatic polyester (PCL). The solution pH did not affect the hydrolytic degradation rate of PCL (a 3% Mn loss after six weeks). The presence of a PDMAEMA component in the copolymer chain increased the hydrolysis rates and depended on the solution pH, as PCL-b-PDMAEMA degraded faster in an acidic environment (36% Mn loss determined) than in a slightly alkaline environment (27% Mn loss). Enzymatic degradation of PCL-b-PDMAEMA, poly(d,l-lactide)-block-poly(N,N′-dimethylaminoethyl methacrylate) (PLA-b-PDMAEMA) and poly(lactide-co-glycolide-co-ε-caprolactone)-block-poly(N,N′-dimethylaminoethyl methacrylate) (PLGC-b-PDMAEMA) and the corresponding aliphatic polyesters (PCL, PLA and PLGC) was performed by Novozyme 435. In enzymatic degradation, PLGC degraded almost completely after eleven days. For polyester-b-PDMAEMA copolymers, enzymatic degradation primarily involved the ester bonds in PDMAEMA side chains, and the rate of polyester degradation decreased with the increase in the chain length of PDMAEMA. Amphiphilic copolymers might be used for biomaterials with long-term or midterm applications such as nanoscale drug delivery systems with tunable degradation kinetics.
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Morrow, Cary J. "Biocatalytic Synthesis of Polyesters Using Enzymes." MRS Bulletin 17, no. 11 (1992): 43–47. http://dx.doi.org/10.1557/s0883769400046650.
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Plants and animals have been exploited as sources of materials for centuries but, as our ability to analyze and fractionate them has progressed, the extraordinary range of properties available from materials produced by living systems has continued to grow. Doi, in another article in this issue of the MRS Bulletin, presents a discussion of a group of naturally occurring polyesters related to poly(beta-hydroxybutyrate). These polyesters are formed in vivo by several microorganisms as part of an energy storage scheme. Research on these systems has allowed growth conditions to be found that can lead, in a controlled fashion, to a number of copolymers. Useful materials based on these bacterial polyesters appear to be at hand.The in-vivo formation of polyesters in microorganisms also illustrates several of the important reasons for examining biocatalytic polymer synthesis. First, unlike most industrial syntheses of polyesters, the poly(beta-hydroxybutyrate) biosynthesis occurs at a near-ambient temperature using a carbohydrate feedstock. Second, and perhaps most importantly, the stored polyesters are readily biodegraded by the bacteria that manufacture them, so materials based on these polyesters should also be biodegradable. Third, although there are side chains along the polymer backbone, they are introduced in a highly stereo-specific fashion during in-vivo synthesis, leading to an entirely stereoregular polyester. However, along with these advantages, there are also significant limitations to bacterial polyester synthesis. First, there are some substrates that are not incorporated into the polyester by the bacteria. Second, normal metabolism leads to the polyester, always incorporating a fraction of hydroxybutyrate monomers. Third, the backbone is always comprised of four-atom, A-B type 3-hydroxy acid repeat units with variations appearing in the side chain at carbon-3.
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Meleshko, T. K., A. B. Razina, N. N. Bogorad, et al. "Synthesis of Poly(ester-graft-methyl methacrylate) on a Macroinitiator with Lateral Sulfonyl Chloride Groups by Atom Transfer Radical Polymerization." Polymer Science, Series B 63, no. 4 (2021): 385–91. http://dx.doi.org/10.1134/s1560090421040072.
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Abstract New polymer brushes with an ester backbone and poly(methyl methacrylate) side chains are synthesized by polycondensation and polymerization methods. The initiating groups are sulfonyl chloride groups laterally attached to the polyester chain. PMMA side chains are grafted by the ATRP method according to the “grafting from” multicenter macroinitiator strategy. The conditions for the polymerization processes in a controlled mode are selected, and the ways of targeted regulation of the degree of polymerization of methacrylate side chains are determined. Using the synthesized copolymers self-supporting films are obtained, and their physical and mechanical properties are studied.
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Śmigiel-Gac, Natalia, Elżbieta Pamuła, Małgorzata Krok-Borkowicz, Anna Smola-Dmochowska, and Piotr Dobrzyński. "Synthesis and Properties of Bioresorbable Block Copolymers of l-Lactide, Glycolide, Butyl Succinate and Butyl Citrate." Polymers 12, no. 1 (2020): 214. http://dx.doi.org/10.3390/polym12010214.
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The paper presents the course of synthesis and properties of a series of block copolymers intended for biomedical applications, mainly as a material for forming scaffolds for tissue engineering. These materials were obtained in the polymerization of l-lactide and copolymerization of l-lactide with glycolide carried out using a number of macroinitiators previously obtained in the reaction of polytransesterification of succinic diester, citric triester and 1,4-butanediol. NMR, FTIR and DSC were used to characterize the materials obtained; wettability and surface free energy were assessed too. Moreover, biological tests, i.e., viability and metabolic activity of MG-63 osteoblast-like cells in contact with synthesized polymers were performed. Properties of obtained block copolymers were controlled by the composition of the polymerization mixture and by the composition of the macroinitiator. The copolymers contained active side hydroxyl groups derived from citrate units present in the polymer chain. During the polymerization of l-lactide in the presence of polyesters with butylene citrate units in the chain, obtained products of the reaction held a fraction of highly branched copolymers with ultrahigh molecular weight. The reason for this observed phenomenon was strong intermolecular transesterification directed to lactidyl side chains, formed as a result of chain growth on hydroxyl groups related to the quaternary carbons of the citrate units. Based on the physicochemical properties and results of biological tests it was found that the most promising materials for scaffolds formation were poly(l-lactide–co–glycolide)–block–poly(butylene succinate–co–butylene citrate)s, especially those copolymers containing more than 60 mol % of lactidyl units.
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Saner, B., Y. Z. Menceloglu, and N. Bilgin Oncu. "Branched Pentablock Poly(L-lactide-co-∊-caprolactone) Synthesis in scCO2." High Performance Polymers 19, no. 5-6 (2007): 649–64. http://dx.doi.org/10.1177/0954008307081209.
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Pentablock poly(L-lactide-co-∊-caprolactone) (PLLA/PCL), with a central fluorinated segment and four PLLA/PCL side chains was synthesized by sequential ring-opening polymerization (ROP) with stannous octoate catalyst in an environmentally benign and clean medium, scCO2. Copolymers of PLLA and PCL are extensively researched for biomedical applications. Fluorinated hydrocarbons are similarly promising for biomedicine, and especially for oxygen-carrying substitute applications. Initially, a fluorinated reactive triblock stabilizer (prepolymer, PCL-FLKT-PCL) with inner fluorinated segment and PCL side chains was synthesized in bulk from a tetraol fluorinated alcohol (FLKT) with a 99% conversion. The prepolymer was then utilized for the synthesis of copolymers in scCO2, where PLLA segments were successively incorporated to the ends of the prepolymer, forming a pentablock structure with four polyester side chains. Reactions were carried out at 75°C and 4000-4500 psi. Solubility studies of the prepolymer and the pentablock copolymer in scCO2 showed effective solubilization at the reaction temperature and pressure. The molecular weights of the products were measured with the aid of gel permeation chromatography; the prepolymer and the copolymer possessed average number molecular weights (Mn) in the range of 13 000 and 24 000 (for 96% conversion of LLA), respectively. Low poly-dispersity indexes were obtained: 1.34 for the prepolymer and 1.08-1.34 for the pentablock copolymer. Material characterization was carried out by 1H NMR, 13C NMR, 19F NMR, differential scanning calorimetry (DSC), gel permeation chromatography (GPC) and scanning electron microscopy (SEM).
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Polloni, André E., Viviane Chiaradia, Ronaldo José F. C. do Amaral, et al. "Polyesters with main and side chain phosphoesters as structural motives for biocompatible electrospun fibres." Polymer Chemistry 11, no. 12 (2020): 2157–65. http://dx.doi.org/10.1039/d0py00033g.
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Scholsky, K. M., E. B. Orler, K. J. Bixler, and R. W. Stackman. "Thermal and rheological properties of acrylic copolymers possessing crystallizable polyester side chains." Makromolekulare Chemie. Macromolecular Symposia 42-43, no. 1 (1991): 219–28. http://dx.doi.org/10.1002/masy.19910420118.
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Deng, Xin-Xing, Yang Cui, Yao-Zong Wang, Fu-Sheng Du, and Zi-Chen Li. "Graft Copolymers with Polyamide Backbones via Combination of Passerini Multicomponent Polymerization and Controlled Chain-growth Polymerization." Australian Journal of Chemistry 67, no. 4 (2014): 555. http://dx.doi.org/10.1071/ch13450.
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We report a facile ‘grafting from’ approach to graft copolymers with polyamide backbones and controlled vinyl polymer or polyester side chains. Two polyamides with in situ-formed pendant bromide or hydroxyl groups were obtained by Passerini-based multicomponent polymerization. They were used respectively to initiate the atom-transfer radical polymerization of vinyl monomers or the ring-opening polymerization of lactones to generate two new types of graft copolymers. One of the important features of the method is that the pendant initiators are generated in situ from non-branching monomers, and they are linked to the polymer backbone by ester bonds. Therefore, the vinyl polymer side chains could be detached from the backbones, and their structures could thus be fully characterized. Moreover, multicomponent polymerization and atom-transfer radical polymerization can even be carried out in a one-pot manner.
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Wu, Kaiting, Xiaobin Chen, Siyi Gu, et al. "Decisive Influence of Hydrophobic Side Chains of Polyesters on Thermoinduced Gelation of Triblock Copolymer Aqueous Solutions." Macromolecules 54, no. 16 (2021): 7421–33. http://dx.doi.org/10.1021/acs.macromol.1c00959.
Full textDissertations / Theses on the topic "Polyesters; Copolymers; Side chains"
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He, Zhi-qun. "Structural modification in rigid and semi-flexible polymers." Thesis, University of Reading, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240319.
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Podhajecka, Klara. "Associating water-soluble copolymers : the role of hydrophobic side-chains on the self-assembling properties of grafted macromolecules." Paris 6, 2005. http://www.theses.fr/2005PA066239.
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Chang, Yi-Cheng, and 張益誠. "Synthesis and Properties of Acrylamide-Acrylate Copolymers with Terpyridine Side-Chains." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/4v98c6.
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碩士<br>國立臺北科技大學<br>化學工程研究所<br>100<br>We synthesized an acrylamide monomer containing 4’ substituted 2, 2’ : 6’ , 2”-terpyridine. The free radical polymerization of acrylamide and acrylate was initiated by 2,2''-azobisisobutyronitrile (AIBN). The homopolymers and the random copolymers with pendent terpyridine or ethoxyethoxyethyl functional group were polymerized by different feeding ratios. The thermal properties, optical properties and solubility of polymers were investigated and discussed.
The structures of monomers and polymers were confirmed by mass spectrometer, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy. The polymers showed excellent solubility in aprotic polar organic solvent such as DMF, NMP. The polymers with higher ethoxyethoxyethyl contents had better solubility in organic solvents such as toluene, 1,4-dioxane. The polymers exhibited UV-vis absorption bands at 274 to 287 nm in THF/MeOH (25:1) solution. The glass transition temperatures are about -58 to 227 ℃, the temperature at 5% and 10% weight loss measured by a TGA are 224 to 357 ℃ and 267 to 373 ℃, respectively, under nitrogen. The acrylamide and acrylate copolymers exhibited UV-vis absorption bands at 274 to 287 nm and showed PL maximum emission peaks at 372 ~ 389nm in THF/MeOH (25:1) solution. Regarding the colorimetric determination of transition metal, we found that maximum absorption band at 287 nm decreases in gradual with increasing concentration of transition metal ion In addition, a new absorption band appeared at 340 ~ 384 nm and the intensity increased gradually based on the increase of transition metal ion. According to PL spectra, we could find the maximum emission peak at 389 nm (415 nm for Hg2+)was quenched and blue shifted gradually. But in the cases of Zn2+, Hg2+, a new emission peak appeared at wavelength larger than 450 nm, especially higher PL intensity was observed for the case of Zn2+. Based on the selective characteristic for Zn2+, we did a simple experiment by handheld UV lamp. The result showed the emission color changed from the light blue to bright yellow color when the polymer containing Zn2+ was excited by 365 nm light, but this phenomenon did not observed toward the other transition mental ions.
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Ching, Chuang Yi, and 莊宜靜. "Synthesis and Characterization of PEG and Cholesterol Side Chains Containing Amphiphilic Comb Copolymers." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/64258057325401661712.
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碩士<br>國立臺灣科技大學<br>化學工程系<br>89<br>Abstract
In this study, novel amphiphilic graft copolymers comprising hydrophobic cholesterol side chains and hydrophilic PEG side chains were synthesized and characterized. The structures and compositions of these graft copolymers were determined quantitatively by NMR. The number of cholesterol side chains first increases and then levels off when the amount of cholesteryl chloroformate used in the grafting reaction increases. The weight-average molecular weight of these copolymers are smaller than 6×104 and they can form micelles in the aqueous solution. The critical micelle concentration (CMC) of copolymers is closely related to their hydrophile-lipophile balance properties. CMC increases with increasing hydrophilicity of copolymers. The colloidal stability of all polymeric micelle solutions is quite satisfactory, as illustrated by the particle size versus time data. Pyrene was used as a model compound to study the partitioning and release behaviors of hydrophobic molecules in polymeric micelle systems. In general, the more hydrophobic the copolymer is, the larger is the amount of pyrene that can be incorporated into polymeric micelles. The release rate of pyrene from polymeric micelles is also dependent on the hydrophile-lipophile balance properties; the pyrene release rate increases with increasing hydrophilicity of copolymers.
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Tai, Pao-Yi, and 戴寶羿. "Syntheses and Properties of Donor(3T)-Acceptor(TPD) Conjugated Copolymers with Fluorinated Side Chains." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/dgsned.
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碩士<br>國立臺灣大學<br>材料科學與工程學研究所<br>107<br>Optoelectronic active conjugated donor-acceptor alternating copolymers have potential in the applications of lightweight and flexible optoelectronic devices. How to design polymers that can be self-assembled into long-range highly ordered structures and to enhance the performance of devices is a very important research field. Previous research showed that the oligoether side chain can promote the long-range ordered structures in copolymers. However, the hydrophilicity of oligoether limits the copolymer to be fabricated into high sensitivity devices.
In this research, through side chain engineering, we design and synthesize new copolymers containing fluoroalkyl side chain. They can exhibit not only long-range ordered structures and good optoelectronic property but also exceptional hydrophobic property and thermal stability. We choose terthiophene (3T) as donor and thieno[3,4-c]pyrrole-4,6-dione（TPD）as acceptor to build alternating copolymers. Three kinds of side chains: alkyl (R1), semifluoroalkyl (SF) and perfluoroalkyl (F) are placed on 3T respectively; alkyl side chain (R2) and oligoether side chain (E) are placed on TPD respectively. Through Stille coupling reaction, six polymers are synthesized. The properties of polymers were investigated by contact angle measurement, glancing incident wide angle scattering spectroscopy, UV-Vis spectroscopy, cyclic voltammetry and thermal analysis.
Regardless the side chain type is R2 or E on TPD, the contact angle is increased with increasing the amount of F on the side chain of 3T. Upon annealing, the polymers contain R2 side chain self-assembled into hexagonal cylinder structure. The structure is changed to lamella for the copolymers containing either SF or F side chain. By increasing the amount of F on the side chain, the blue shift of λmax of UV-Vis absorption is increased; EHOMO and ELUMO levels are lowered; the thermal stability (Td) is increased. On the contrary, regardless the side chain type on 3T, decreased contact angle, thermal stability and bandgap are observed for polymers with E side chain as compared with R2 side chain. However, the E side chain improves the extent of structure ordering and increasing EHOMO and ELUMO levels of the copolymers.
In conclusion, we effectively improve the hydrophobicity and thermal stability of oligoether side chain on TPD of 3T-TPD alternating copolymer by placing either semifluoro or perfluoro alkyl side chain on 3T. Their self-assembly behaviors and optoelectronic properties of copolymers are also altered. The formation of highly ordered long-range lamella structure for new fluoro-containing copolymers will promote the charge transport that will be useful in the applications of sensors and transistors.
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Chen, Po-Cheng, and 陳柏丞. "New Donor-Acceptor Random Copolymers with Side-Chains of para-Substituted Dicyano-triphenylamine and Oxadiazole Derivatives : Synthesis, Properties, and Memory Device Applications." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/14006543273846013037.
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碩士<br>國立臺灣大學<br>化學工程學研究所<br>97<br>In recent years, polymer systems have attracted significant research interest for memory device applications due to their tunable electrical properties through molecular design and good processibility. The representative classes of polymer materials used for fabrication on memories are conjugated polymers, non-conjugated polymers (functional polyimide systems or polymers with specific pendent donor or acceptor moiety) and polymer nanocomposites (metal nanoparticle or fullerene embedded). However, the effects of polymer structure on the memory characteristics have not been fully explored yet. In this thesis, the homopolymers pendant with donors or acceptors and related copolymers containing of both donor and accepter units were synthesized and evaluated on memory devices.
In chapter 2, the homopolymers with pendant para-substituted dicyano- triphenylamine (D, as donor) or three different oxadiazole derivatives (2-phenyl-5-(4-vinylphenyl)-1,3,4-oxadiazole (A1), 2-(4-vinylbiphenyl)-5-(4-phenyl)- 1,3,4-oxadiazole (A2), and 2-(4-vinylbiphenyl)-5-(4-ethoxyphenyl)-1,3,4-oxadiazole (A3), as electron acceptor) and also related random copolymers consisting of pendant donor and acceptor moieties (the ratio of donor:acceptor is 8:2, 5:5 and 2:8, respectively) were synthesized by Nitroxide-Mediated Living Free Radical Polymerization (NMP) and characterized by 1H NMR spectrum and element analysis (EA). The para-substituted dicyano groups on triphenylamine improve the stability without the dimerization. The side-chain acceptor A2 shows more conjugated length relative to A1 by introducing another benzene ring, and A3 system further enhances the electronic density by adding terminal electron donating moiety (-OEt). The two thin film absorbance peaks of copolymers at 353 nm and 308 ~ 332 nm belong to the corresponding homopolymers (PD at 355 nm, PA1 at 308 nm, PA2 at 330 nm, PA3 at 332 nm, respectively) and the relative absorbance of two peaks vary with donor and acceptor ratios. The band gaps calculated from absorption edge are in the range of 3.11 ~ 3.20 eV and increase slightly with the larger acceptor content. The HOMO and LUMO energy levels of the random copolymers with different donor and acceptor ratios obtained from cyclic voltammetry (CV) are almost the same with the corresponding HOMO level of donor (-5.63 eV) and LUMO levels of acceptor (-2.63 ~ 2.81 eV), respectively, mainly due to poor hybridization of adjacent donor and acceptor which could be considered as an isolated system. The electronic properties can be well-tuned through different donor-acceptor structures and ratios of the copolymers systems.
In chapter 3, the memory device of the random copolymers and homopoymers are fabricated and measured in ambient atmosphere. Different solvents (N,N-dimethyl formamide (DMF) or chlorobenzene (CB)) are chosen for polymer thin film processing. The bistable memory behavior is conducted by a simple sandwich device configuration consisted of spin-coated polymer film between indium-tin oxide (ITO) bottom electrode and aluminum (A1) top electrode. All the polymers exhibit nonvolatile flash type of switching behavior. The memory devices have low turn-on threshold voltage below 1 V and exhibits long retention time of 11000 seconds. The mechanism of the switching behavior is based on filamentary conduction with space charge limited current (SCLC) theory. As the polymer films prepare from DMF, the OFF state current during erasing scan increases from 10-5 A to 10-2 A after several WRER cycles. These phenomena are further obviously demonstrated in the case of the larger acceptor contents of the random copolymers (5:5 and 2:8 donor:acceptor ratio) and homopolymers pendant with acceptor due to the presence of the binding heteroatom (N) on acceptor with Al which contributes to filament conductions. Introducing electron donating ethoxy substituent (A3) which enhance the binding ability of N atom of oxadiazole group makes the memories difficult to turn off and also keep them on the high conductance since the stable filament channel are formed. The memory can still restore to the initial OFF state if the erasing process scan more negatively which also means the enhanced threshold voltage (from -3 V to -5 V) as the acceptor ratio increases. The polymer surface prepared from the CB solution is smooth and the current elevation of OFF state during the erasing switch could not be found. The study demonstrates that pendent donor/acceptor structures and ratio of copolymer and processing condition on the switching characteristics of memory device are fully explored.
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Maity, Soham. "Synthesis And Self-Assembly Properties of Chiral Diketopyrrolopyrrole Based Copolymers." Thesis, 2016. http://etd.iisc.ernet.in/handle/2005/2700.
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Applications of conjugated polymer (CPs) in optoelectronic devices are critically depend on nature of thin film morphology. In thin film of CPs, the distribution of conjugation length is highly heterogeneous because of conformational defects, distortions of polymer chain and aggregates. A greater understanding of the self-assembly properties of polymer in solution, in particular control over aggregation leads to richer description of electronic properties and hence reproducible fabrication of thin film devices. Recently, chiral CPs have attracted profound interest because of their promising chiroptical properties in thin films and easy control over the selective agglomeration process. In this thesis, we have investigated the role of chiral side-chains on a series of thiophene diketopyrrolopyrrole (TDPP)-benzodithiophene (BDT) based copolymers. Chiral 3,7-dimethyloctyl chain was introduced as an asymmetric chain to incorporate chirality on one of the repeating unit (TDPP) of copolymers. Two polymers with side-chains of identical chirality (S),(S)-PTDPP-BDT; (R),(R)-PTDPP-BDT and a third polymer with similar side-chains of opposite chirality (R),(S)-PTDPP-BDT were synthesized. The chiroptical properties were investigated by UV-visible and circular dichroism (CD) spectroscopy.
Figure 1: The structure of the TDPP-BDT copolymers.
The copolymers dissolved in a good solvent (e.g. chloroform, chlorobenzene) in which polymers adopts random coil conformation, no chiral response has been observed. However, a critical addition of non-solvent (methanol), the copolymers stack in a chiral fashion and leads to typical bisignate Cotton effects. It is noteworthy that the two polymers, (S),(S)-PTDPP-BDT and (R),(R)-PTDPP-BDT exhibiting a nearly ideal mirror-image relationship in CD spectra (Figure 2a) whereas the (R),(S)-PTDPP-BDT lacks chiropticity even with the addition of methanol. The aggregation induced CD phenomena are dependent on the temperature of solution and do not exhibit reversibility in a heating-cooling cycle.
Figure 2: (a) The mirror image Cotton effects of (S),(S)-PTDPP-BDT and (R),(R)-PTDPP-BDT (b) No CD signal was observed for the (R),(S)-PTDPP-BDT polymer.
Figure 3: The variation of (a) UV-vis and (b) CD spectra of (R),(R)-PTDPP-BDT polymer with thickness of the solid film.
To investigate the role of thickness and annealing temperature on optical and chiroptical properties of polymer films, thin films were prepared using drop-casting method from a solution of chlorobenzene. Both the polymer showed gradual enhancement of CD signal with the increase of film thickness but we did not see any such order with temperature (Figure 3).
Figure 4: The morphology observed for the film by (a) AFM; (b); (c) FESEM.
The thin film morphology of polymers is characterized by atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) (Figure 4). AFM studies show the polymer molecules self-assembled and formed interconnected nanofibers. Whereas FESEM images clearly revealed that, the nanofibers of polymers are predominantly stack in a chiral fashion and mimic a one-handed helix which leads to bisignate Cotton effects. The (S),(S)-PTDPP-BDT and (R),(R)-PTDPP-BDT form fibers with opposite handedness whereas (R),(S)-PTDPP-BDT do not have such preferred handedness. The research described in this thesis aims to explore the role of chiral side-chains to impose chiral stacking and hence resulting chiral expression. Chirality in this class of polymers may endows them promising optoelectronic properties.
(For figures pl see the abstract pdf file)
Book chapters on the topic "Polyesters; Copolymers; Side chains"
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Takahashi, M., S. Hamaguchi, H. Ito, T. Imae, and T. Nakamura. "Association of block copolymers with dendritic and perfluorinated side chains in solution and at an interface." In Surface and Colloid Science. Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/b97084.
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Otsuka, Hideyuki, Yoshifumi Amamoto, Yasuhiro Matsuda, Takeshi Maeda, and Atsushi Takahara. "Synthesis and Reaction of Well-defined Copolymers with Thermally Exchangeable Dynamic Covalent Bonds in the Side Chains." In ACS Symposium Series. American Chemical Society, 2009. http://dx.doi.org/10.1021/bk-2009-1024.ch021.
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Mark, James E., Dale W. Schaefer, and Gui Lin. "Copolymers and Interpenetrating Networks." In The Polysiloxanes. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780195181739.003.0010.
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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, &gamma;-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.
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Hua, Fengjun, and Eli Ruckenstein. "Copolymers of Aniline and 3-Aminophenol Derivatives with Oligo(oxyethylene) Side Chains as Novel Water-Soluble Conducting Polymers *." In Solution and Surface Polymerization. CRC Press, 2019. http://dx.doi.org/10.1201/9780429027420-23.
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Mark, James E., Harry R. Allcock, and Robert West. "Polysiloxanes and Related Polymers." In Inorganic Polymers. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780195131192.003.0008.
Full textAbstract:
At the present time, polysiloxanes are unique among inorganic and semi-inorganic polymers. They have been the most studied by far, and are the most important with regard to commercial applications. Thus, it is not surprising that a large number of review articles exist describing the synthesis, properties, and applications of these materials. The Si-O backbone of this class of polymers endows it with a variety of intriguing properties. For example, the strength of this bond gives the siloxane polymers considerable thermal stability, which is very important for their use in high-temperature application (for example as heat-transfer agents and high-performance elastomers). The nature of the bonding and the chemical characteristics of typical side groups give the chains a very low surface free energy and, therefore, highly unusual and desirable surface properties. Not surprising, polysiloxanes are much used, for example, as mold-release agents, for waterproofing garments, and as biomedical materials. Some unusual structural features of the chains give rise to physical properties that are also of considerable scientific interest. For example, the substituted Si atom and the unsubstituted O atom differ greatly in size, giving the chain a very irregular cross section. This influences the way the chains pack in the bulk, amorphous state, which, in turn, gives the chains very unusual equation-of-state properties (such as compressibilities). Also, the bond angles around the O atom are much larger than those around the Si, and this makes the planar all-trans form of the chain approximate a series of closed polygons. As a result, siloxane chains exhibit a number of interesting configurational characteristics. These structural features, and a number of properties and their associated applications, will be discussed in this chapter. The major categories of homopolymers and copolymers to be discussed are linear siloxane polymers [-SiRR'O-] (with various alkyl and aryl R,R' side groups), (ii) sesquisiloxane polymers possibly having a ladder structure, (iii) siloxane-silarylene polymers [-Si(CH3)2OSi(CH3)2(C6H4)m-] (where the skeletal phenylene units are either meta or para), (iv) silalkylene polymers [-Si(CH3)2(CH2)m-], and (v) random and block copolymers, and blends of some of the above. Topics of particular importance are the structure, flexibility, transition temperatures, permeability, and other physical properties.
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Mark, James E., Dale W. Schaefer, and Gui Lin. "Introduction." In The Polysiloxanes. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780195181739.003.0003.
Full textAbstract:
Polysiloxanes are unique among inorganic and semi-inorganic polymers; they are also the most studied and the most important with regard to commercial applications. Thus, it’s not surprising that there is an extensive literature describing the synthesis, properties, and applications of these materials, including books, proceedings books, sections of books or encyclopedias, review articles, and historical articles. The purpose of this volume is not to give a comprehensive overview of these polymers but rather to focus on some novel and interesting aspects of polysiloxane science and engineering, including properties, work in progress, and important unsolved problems. The Si-O backbone endows polysiloxanes with a variety of intriguing properties. The strength of the Si-O bond, for example, imparts considerable thermal stability, which is important for high-temperature applications (e.g., as heat-transfer agents and high-performance elastomers). The nature of the bonding and the chemical characteristics of typical side groups impart low surface free energy and therefore desirable surface properties. Polysiloxanes, for example, are used as mold-release agents, waterproofing sprays, and biomedical materials. Structural features of the chains give rise to physical properties that are also of considerable scientific interest. For example, the substituted Si atom and the unsubstituted O atom differ greatly in size, giving the chain a nonuniform cross section. This characteristic affects the way the chains pack in the bulk, amorphous state, which explains the unusual equation-of-state properties (such as compressibility). Also, the bond angles around the O atom are much larger than those around the Si, which makes the planar all trans form of the chain approximate a series of closed polygons, as illustrated in figure 1.1. As a result, siloxane chains exhibit a number of interesting configurational characteristics that impact properties and associated applications. The major categories of homopolymers and copolymers to be discussed are (i) linear siloxane polymers -SiRR’O-] (with various alkyl and aryl R,R&rsquo; side groups), (ii) sesquisiloxane polymers possibly having a ladder structure, (iii) siloxane-silarylene polymers [–Si(CH3)2OSi(CH3)2(C6H4)m –] (where the skeletal phenylene units are either meta or para), (iv) silalkylene polymers [–Si(CH3)2(CH2)m–], and (v) random and block copolymers, and blends of some of the above.
Conference papers on the topic "Polyesters; Copolymers; Side chains"
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Dasgupta, Chanchal. "New Materials for Protection of City Gas Distribution Networks." In ASME 2019 India Oil and Gas Pipeline Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/iogpc2019-4520.
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Polyethylene pipes and Steel pipes with 3LPE coatings are integral part of a citygas distribution network. These are being used in India since late 80’s. Standard MDPE and HDPE materials are Butene copolymers of Ethylene, where Butene (C4) is added as comonomer to form the side branches of linear Polyethylene (C2) chains. The research on PE materials have improved various attributes of the polymer, providing them with higher durability, pressure resistance and service life. One such development is use of Hexene (C6) as a copolymer replacing Butene (C4) to make an Ethylene Hexene copolymer providing superior resistance to mechanical damages and slow crack growth during installation and service. For PE100 Orange pipe materials for low / medium pressure distribution system, the new hexene PE copolymer, offers much superior resistance to slow crack growth. Hence it is ideal for Trenchless installations like HDD or pipe bursting, where pulling the pipe through the bore in the ground may substantially notch and scratch the pipe or coating. Using a Hexene PE service life of the pipe is not affected despite the demanding installation techniques due to higher entanglement of polymer chains. These types of PE materials are already being used by Indian CGD Industry for past 2–3 years. For 3LPE coated steel pipes for high pressure gas mains as well as trunk lines, Hexene based Black PE top coat has been adopted by several Gas companies. This is mainly due to two advantages. They offer a higher upper design temperature limit of +90 C (compared to +80 C as per international specification (ISO21809-1). They also offer material savings as 10% lower thickness compared to standard PE top coat is able to meet and exceed all system requirements. The paper deals with the mechanism of these new polymers that helps to offer these superior properties.