Reaction of living polystyrene with some natural polymers and their analogs

The preparation and characterization of graft polymers of methylated xylan and polystyrene are described. The copolymers were prepared anionically by reaction of polystyrylpotassium with the methyl glucuronate moiety, to give well‐defined comblike structures. Polystyrenes of molecular weight 1,100 and 4,700 were used. The reaction takes place by attack of the polymeric anion at the ester function, which converts it into a ketone. Infrared analysis has confirmed this, since only a ketone absorption band is observed in the grafted products. Evaluation of intrinsic viscosity measurements on well‐defined copolymer fractions was made in terms of branch density, branch length, and backbone molecular weight. These parameters generally affected the viscosity in the manner predicted for homopolymer branched structures. Reactions of the polystyryl anion with a polyester and a polypeptide were also considered. In general, unwanted side reactions were predominant in these systems. However, in the case of one polyester, polypropiolactone, indications are that block copolymers with polystyrene were prepared, but isolation and characterization of the products was not attempted, because of the low molecular weights involved.