Synthesis, Characterization And Potential Application Of Functional Polymers

In this Ph.D.thesis, we synthesized several functional polymers, characterizedtheir specific properties and seeked their potential applications, including the study ofkinetics of thermally sensitive polymers and the hysteresis in their phase transition inwater; the development of a facile method to prepare full-color electrically tunablephotonic crystals; and the synthesis of end group functionalized metal chelatingpolymers based on polyaspartamides and polyglutamides, and investigated theirdegradation in physiological conditions. More specifically,we have1: investigated thermally induced association and dissociation ofpoly(N,N-diethylacrylamide)(PDEAM) chainsin water. The laser light scattering (LLS)and Fourier transform infrared spectroscopy (FTIR) studies showed no hysteresisbetween the association and dissociation of PDEAM chains in water during oneheating and cooling cycle. The US-DSC study showed that phase transitiontemperature and the enthalpy change in heating and cooling process are almost equalat a low scanning rate. The current study confirms that the hysteresis previouslyobserved for a sister polymer, poly(N-isopropylacrylamide) (PNIPAM), is due to theformation of additional intra- and inter-chain hydrogen bonds in the collapsed state attemperatures higher than its LCST.2: studied the kinetics of phase transition of poly(N-isopropylacrylamide)(PNIPAM) chains over a wide concentration range from dilute to semidilute regimeby using a home-made fluorescence spectrometer equipped with an ultrafast pulsedinfrared laser. Our results have revealed that there exist two characteristic transitiontimes in dilute regime, namely, the fast process (τpearls～0.02 ms) for the formation ofsmall individual pearls along he chain and the slow process (τcoarsening～0.2 ms) for themerging and corsing of individual pearls. For concentrations higher than the overlapconcentration, there occurs the third process (τdisentangling～1.5 ms) whose contributionincreases with concentration. The third process can be attributed to the chaindisentanglements of their overlapped points, which enables us to probe theinhomogeneity of the chain segments.3: developed a new type of electrically tunable photonic crystals with a full colordisplay. The advantages of such PCs are their facile preparation, low driving voltage and good durability, which make them potentially useful in information technologies.4:synthesized polyaspartamide and polyglutamide metal chelating polymerbased on pendant group modification and studied their uncatalyzed degradation undermodel physiological conditions. We found that the polyglutamide polymers werestable over the 14 days of our study and the degradation rates of polyaspartamideswere very sensitive to the nature of the pendant groups of the backbone as well as thecharge density along the chain. The present study revealed that the degradation ratesof the polyaspartamides can be adjusted by the pendant groups and these metalchelating polymers will be used as a carrier for the targeted delivery of 111In in theform of radioimmunoconjugates.