Brush type copolymers of poly(3-hydroxybutyrate) and poly(3-hydroxyoctanoate) with same vinyl monomers via "grafting from" technique by using atom transfer radical polymerization method

Brush type graft copolymers of poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxyoctanoate) (PHO) with methyl methacrylate, (MMA), styrene, (S), and n-butylmethacrylate, (n-BuMA) were obtained by using Atom Transfer Radical Polymerization Method, (ATRP), via "grafting from" technique. Firstly PHB and PHO were chlorinated by passing chlorine gas through their solution in CHCl3/ CCl4 (75/25 v/v) mixture and CCl4, respectively, in order to prepare chlorinated PHB, PHB-Cl, and chlorinated PHO, PHO-Cl, with different chlorine contents. The determination of the chlorine content in chlorinated poly(3-hydroxyalkanoate) (PHA-Cl) was performed by the Volhard Method. Then ATRP of vinyl monomers was initiated by using PHA-Cl as macroinitiators in the presence of cuprous chloride (CuCl)/2,2 '-bipyridine complex as catalyst, at 90 degrees C in order to obtain brushes containing PHAs. The polymer brushes were fractionated by fractional precipitation methods and the gamma values calculated from the ratio of the volume of nonsolvent (methanol) and the volume of solvent (chloroform) of brushes varied between 0.82 and 6.50 depending on the composition of brushes. The polymer products were characterized by gel permeation chromatography (GPC), H-1 NMR, FTIR, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques.