New telechelic polymers and sequential copolymers by polyfunctional initiator-transfer agents (inifers) LVII. Chlorine telechelic poly(p-chlorostyrene)

The polymerization of p-chlorostyrene (pClSt) under carbocationic conditions has been investigated. The use of binifers 1,4-di(2-chloro-2-propyl) benzene (pDCC) and 1,3-di(2-chloro-2-propyl)-5-tert-butylbenzene (m-tBuDCC) in conjunction with BCl₃ coinitiator in CH₃Cl diluent at ?60 and ?35°C give α,ω-di-benzylic chlorine-capped polymer ^sCl? PpClSt? Cl^s. According to kinetic investigations the inifer mechanism is operative and both binifers are efficient in controlling the end structures, molecular weights, and to a certain extent molecular weight distributions (MWD). Strong circumstantial evidences have been generated to demonstrate the satisfactory synthesis of ^sCl? PpClSt? Cl^s and the absence of indanyl end-groups, i.e., structural considerations, linearity of inifer plots, quantitative Cl end-group microanalysis, FTIR spectroscopy, and blocking experiments. The latter involved the blocking of THF from the sec-benzylic chlorine end-groups by AgPF₆ and thus led to the synthesis of a new triblock copolymer PTHF-b-PpClSt-b-PTHF. Interestingly, the isotactic content (mm triads and mmmm pentads) of PpClSt is significantly higher than that of polymer prepared by free-radical induced polymerization. The T_g of a PpClSt of M?_n = 5700 g/mol was 123°C.