Thermal Properties of Oligo(2-ethyl-2-oxazoline) Containing Comb and Graft Copolymers and their Aqueous Solutions

Summary: The cationic ring opening polymerization of 2-ethyl-2-oxazoline (EtOx) was applied for the synthesis of methacrylate end-functionalized well-defined macromonomers that could be polymerized in a controlled manner using reversible addition-fragmentation chain transfer polymerization. The obtained comb polymers revealed lower critical solution temperature behavior in aqueous solution. The cloud points of these solutions could be tuned in a range from 35 °C to 85 °C by the incorporation of hydrophobic methyl methacrylate comonomer in varying amounts into the graft copolymers whereas copolymerization with methacrylic acid rendered temperature and pH sensitive copolymers. Thermo-gravimetric analysis showed a two-step decomposition of the graft copolymers and differential scanning calorimetry revealed glass transition temperatures that are significantly lowered in comparison to linear PEtOx.     

聚苯乙烯-聚硅氧烷规整接枝共聚物界面形态

为充分发挥有机硅的“有机-无机”双重特性的作用，研究用反应性有机硅改性其它高分子材料，以聚硅氧烷大分子单体制备了聚苯乙烯-聚硅氧烷规整接枝共聚物．采用傅立叶变换红外光谱仪表征了接枝共聚物的结构，用接触角测量仪和X-射线光电子能谱研究了共聚物在不同基材上成膜的表面和界面组成及相分离程度．结果表明：接枝共聚物呈现典型的层状相分离结构；PDMS在膜表面实现最大限度地富集，且对不同界面其富集程度不同；接枝共聚物的表面疏水性随着PDMS链长的增加而增加，且当PDMS含量增加时，呈现先增加后保持不变的趋势．     

Synthesis of hydrogels from a polymeric N,N′-diallyl-N,N′-dimethylammonium salt

Feasibility in principle has been demonstrated for obtaining hydrogels with controlled parameters of the three-dimensional network by copolymerization of N,N-methylenebisacrylamine with macromolecules of poly-N,N-diallyl-N,N-dimethylammonium chloride containing terminal double bonds, i.e., with macromonomers of N,N-diallyl-N,N-dimethylammonium chloride. The hydrogels that are obtained have high anion-exchange capacities.A. V. Topchiev Institute of Petrochemical Synthesis, Academy of Sciences of the USSR, Moscow 117912. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 851–854, April, 1992.     

Preparation of micron-size monodisperse polymer particles by dispersion copolymerization of styrene with poly(2-oxazoline) macromonomer

This article describes the preparation of micron-size monodisperse polymer particles by dispersion copolymerization of styrene with a poly(2-oxazoline) macromonomer in an aqueous ethanol solution. The macromonomer acted as a comonomer as well as a stabilizer. The diameter of the particles increased as the concentration of the macromonomer decreased. The higher the molecular weight of the macromonomer, the smaller the particle size. The copolymerization in the solvent containing higher water content gave smaller polymer particles. Under the condition giving the monodisperse particles, the particles volume increased linearly with the yield of the particles. From ESCA analysis of the particle surface, poly(2-oxazoline) chains were enriched on the surface. © 1993 John Wiley & Sons, Inc.     

Addition–fragmentation behavior of a capto-dative group-substituted acrylic ester in free-radical polymerization and reactivity of the derived macromonomers

Ethyl-2-(2-cyano-2-ethylthio)-ethyl-propenoate (ECEP) was synthesized and examined as free-radical addition–fragmentation chain transfer agent (AFCTA) in the bulk polymerization of methyl methacrylate (MMA) and styrene at various temperatures. A better chain transfer constant (C_tr) was observed for styrene than for MMA, projecting the potentiality of the compound as a better end-functionalizing agent for the former. In both cases, copolymerization of ECEP with the monomer predominated over fragmentation, the relative proportions of which were dependent on the monomer. The ECEP-terminated radical fragmented to an extent of 26% in the presence of MMA, whereas it was only 9.5% in the case of styrene. The relative extent of fragmentation and copolymerization was in conformation to the calculated reactivity ratios and chain transfer constants. Addition–fragmentation chain transfer resulted in the formation of methacrylic-functional macromonomers. The copolymerizability of the resultant macromonomer was found to depend on the nature of the backbone and on the comonomer. On copolymerizing with MMA, the terminal monomer moiety on polystyrene (PS)-based macromonomers preferred to undergo fragmentation, whereas that of the polymethyl methacrylate (PMMA)-based one copolymerized readily with styrene because of thermodynamic and kinetic factors. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2511–2524, 1999     

分散聚合制备聚苯乙烯/聚氧乙烯两亲聚合物微球

聚乙二醇在NaH的作用下和对氯甲基苯乙烯反应制得聚氧乙烯大分子单体 ,然后在乙醇 /水的介质中通过聚氧乙烯大分子单体和苯乙烯的分散共聚制得粒径范围在 0 5～ 1 5 μm ,粒径分布接近单分散的两亲聚合物微球 .对影响微球粒径和粒径分布的各个因素进行了研究 .     

Graft Polymerization of Acryloyloxystarch with Poly (D, L-lactide) Macromonomer——A Potential Drug Delivery Carrier for Oral Administration

Starch is the second largest natural biopolymer. Its unique biodegradable and biocompatible properties make it be increasingly applied to the field of biomedicine. As one kind of polysaccharide, starch is easily degraded into small organic molecules by amylase in the alimentary canal. The fact that the activity of amylase is restrained in the high acid environment in stomach provides an opportunity to prepare an intestinal-specific delivery carrier with     

PEG大分子单体的合成及纳米级微球的制备

以端基反应法合成苯乙烯封端的聚乙二醇（PEG）大分子单体,用凝胶色谱和核磁共振表征它们的相对分子量和末端官能度,发现得到的大分单体的末端有较高的官能度,使该大分子单体与苯乙烯进行接枝共聚,将得到的产物逐步滴加到各种比例的甲醇－水的混合溶剂中,实验发现,接枝共聚物浓度,共聚物中PEG的含量和混合溶剂的比例对纳米微球的形成与聚集形态有明显的影响,X－射线能谱研究表明,微球表面为亲水性PEO,核为疏水的聚苯乙烯,即形成的聚集物为核－壳复合结构的纳米微球。     

Graft copolymers by acyclic diene metathesis and atom transfer radical polymerization techniques

Precise graft copolymer architectures were achieved by combining the macromonomer technique with the acyclic diene metathesis (ADMET) reaction. These well‐defined copolymer structures were the result of proper monomer design before metathesis polymerization. Features such as length of the graft, nature, and concentration of the graft site along the backbone were manipulated via the combination of living atom transfer radical polymerization methods with ADMET chemistry. Furthermore, the physical behavior of these materials was altered such that they presented dissimilar thermal properties of either the homopolymers or random copolymers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2816–2827, 2003     

Amphiphilic polymer gel electrolytes. I. preparation of gels based on poly(ethylene oxide) graft copolymers containing different ionophobic groups

Amphiphilic graft copolymers were prepared via the radical copolymerization of poly(ethylene oxide) (PEO) macromonomers with fluorocarbon or hydrocarbon acrylates in toluene with 2,2′‐azobisisobutyronitrile (AIBN) as an initiator. ¹H NMR spectroscopy confirmed that the composition of the graft copolymers corresponded well to the monomer feed. For gel electrolytes prepared from the amphiphilic copolymers, the nature of the ionophobic parts of the amphiphilic graft copolymers had a great influence on the ion conductivity. Gel electrolytes based on graft copolymers containing fluorocarbon side chains showed significantly higher ion conductivity than electrolytes based on graft copolymers containing hydrocarbon groups. The ambient‐temperature ion conductivity was about 2.6 mS/cm at 20 °C for a gel electrolyte based on an amphiphilic graft copolymer consisting of an acrylate backbone carrying PEO and fluorocarbon side chains. Corresponding gels based on graft copolymers with PEO side chains and hydrocarbon groups showed an ambient‐temperature ion conductivity of about 1.2 mS/cm. The gel electrolytes contained 30 wt % copolymer and 70 wt % 1 M LiPF₆ in an ethylene carbonate/γ‐butyrolactone (2/1 w/w) mixture. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2223–2232, 2001