Synthesis And Solution Properties Of Poly(vinyl Ether) With Long Alkyl Chain Pendants

UCST-type phase separation in organic solvents of poly(vinyl ether)s is of interest. It is well known that vinyl ethers(VEs) are typical monomers for living cationic polymerization. Furthermore, fluorescent-labeled poly(vinyl ether) can be obtained by using a unique terminator at the end of the reaction process of living cationic polymerization. Based on a conventional fluorescence spectrophotometer, the resonance light scattering (RLS) technique is a promising technique to follow phase separation of polymer solutions owing to its high sensitivity, convenience in performance, simplicity, and rapidity. In this work, poly(octadecyl vinyl ether) (PODVE) with long alkyl chain pendants is synthesized by living cationic polymerization, which results in a narrow molecular weight distribution. Phase separation of PODVE/dichloromethane solution is monitored by RLS. On the whole, this work includes two parts as follows:The first part is polymer synthesis and characterization. Living cationic polymerization of ODVE is conducted by using IBEA (1- (isobutoxy) ethyl acetate)/ EtAlCl2 initiating system in the presence of ethyl acetate at 30℃in hexane. Naphthalene-labeled PODVE and ordinary PODVE are obtained employing 2- naphthalenethiol and methanol as terminators, respectively. Varying the molecular weight of PODVE is achieved by changing the concentration of IBEA and polymerization time. Besides, All the polymers are characterized by NMR spectroscopy, FT-IR spectroscopy, GPC measurements and UV-vis spectroscopy.The second part is the study of solution properties. Absorption spectra of different end-capped PODVE and fluorescence spectra of naphthalene-labeled PODVE at room temperature are measured, further indicating the success of the fluorescent-labeling. By using RLS technique, temperature-induced phase separation of PODVE/dichloromethane solution is investigated. We find the temperature dependence of the RLS spectrum intensity at the maximum scattering wavelength reveals the transition of molecular conformation and aggregation of molecular chains in the course of phase separation induced by crystallization during cooling process. On the other hand, heating leads to swelling and dissociation of molecular chain aggregates. Finally, the conformation of PODVE molecular chains returns to its original state at higher temperature. Besides, concentration dependence and molecular weight dependence of the onset temperatures of phase separation (Tp) are collected respectively. Time dependences of phase separation of PODVE/dichloromethane solution at the constant temperatures are also given, which lead to quantitative description of kinetics of phase separation including the estimation of the apparent activation energy by means of Avrami equation and Arrhenius formula.