Temperature-sensitive polymers chemical structure

Owing to multi-functionahty, physical properties such as solubihty and the glass transition temperature and chemical functionahty the hyperbranched (meth) acrylates can be controlled by the chemical modification of the functional groups. The modifications of the chain architecture and chemical structure by SCV(C)P of inimers and functional monomers, which may lead to a facile, one-pot synthesis of novel functionahzed hyperbranched polymers, is another attractive feature of the process. The procedure can be regarded as a convenient approach toward the preparation of the chemically sensitive interfaces. 

In contrast to the rubbery state, the properties of glassy networks (mechanical, thermal) at temperatures markedly below T p do not practically depend on chemical composition and cure conversion at the latest stages of the cure process. The sensitivity of the properties to the chemical structure of the network is very weak. The shortness of intercrosslinked chains is displayed only in small values of eb, e and in the absence of deformation hardening for the glassy state of the considered polymers. 

What family of polymers is very tough, has high melting temperatures, good impact strength, excellent temperature stability, and is moisture sensitive Explain these properties based on the chemical structure of the polymers. 

Temperature-responsive polymers represent a group in which the chemical structure of the polymer is sensitive to temperature changes. Sol-to-gel transition is observed upon environmental temperature change with these polymers and this property can be used for in-vivo delivery of therapeutic agents. For these systems, critical solution temperatures exist, especially in water. At this temperature the phase of polymer and solution is changed in accordance with their composition. The systems which show phase separation below this temperature and one phase above this temperatine hold an upper critical solution temperature (UCST), while polymeric solutions that appear... 

Figure 22.11 Structure of OEGMA-DMAEMA copolymers (left) and their cloud points as function of pH value and monomer composition (right) determined at 0.5 wt% polymer concentration. (Reprinted with permission from D. Fournier, R. Hoogenboom, H.M.L. Thijs et al., Tunable pH- and temperature-sensitive copolymer libraries by reversible addition-fragmentation chain transfer copolymerizations of methacrylates, Macromolecules, 40, 4, 915-920, 2007. 2007 American Chemical Society.)...

The dynamic mechanical tests over a wide temperature range are very sensitive to the physical and chemical structure of polymers and composites. They allow the study of glass transitions or secondary transitions and yield information about the morphology of polymers. Experimental results of dynamic tensile tests (DMTA) conducted on nanocomposites are shown in Table 2 for selected temperatures (20 °C, 100 °C, 220 °C, and glass transition, T ). 

Tsvetanov et al. [61] described the trends in modem polymer science in which one of the most important parameters is the synthesis of the multi-stimuli sensitive polymers, which may have different types of response to pH and temperature changes. In addition, the authors showed the importance of the CRPs in the precise control of the macromolecule structure. Incorporating blocks of different chemical natures in controlled positions of these macromolecules lead to self-assembly in aqueous medium resulting in a diversity of stmctures with multiple types of interactions. The review by Kang and colleagues summarizes very well the developments in CRPs, in particular in bioactive surfaces and biomaterials prepared by ATRP [8],... 

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