Configurational and conformational control of chemical modification and thermal degradation of poly(vinyl chloride)

Abstract

In the light of some earlier works on nucleophilic substitution on poly(viny1 chloride) (PVC) in solution, a conformational mechanism is proposed. It considers the T T isotactic diad conformation t o be the only reactive species and the reaction to be controlled by the conformational equilibria that make such conformation available. A s a result all the isotactic and the heterotactic triads are capable of reacting provided that they adopt the GTTG-and the GTTT c o n f o r m a t i o n , r e s p e c t i v e l y .Since the replacement of a definite fraction of isotactic triads, which are assumed t o be of the GTTG-conformation, results i n an enhanced thermal and photochemical stability, the lability of some chlorines at such triads is proved. Further arguments in favour o f the conformational mechanism are afforded through recent results of i) substitution studies in the melt and i n aqueous suspension with phase transfer catalysts, ii) accurate 1 3~ N M R measurements of triad variation with degree o f substitution.

Chemical modification of poly(epichlorohydrin) with phenolate. Studies of the side reactions

“…The fact that the chlorine atom is not directly attached to the main chain makes nucleophilic substitution easier and stereochemical preferences observed in polymers such as PVC [2] are avoided.…”