Terminal functionalization of polypropylene via the Alder Ene reaction

A terminally anhydride functionalized polypropylene was synthesized via the Alder Ene reaction from a low molecular weight amorphous polypropylene. A Lewis acid, SnCl2·2H2O, was found to catalyse the reaction, thereby improving anhydride content in the polymer for reaction conditions comparable to those in an extrusion environment, i.e. elevated temperature and short residence time. The reaction was carried out at 230°C for 5 min in the presence of TEMPO, which acted as a free radical trap, preventing maleic anhydride from being grafted onto the backbone of the polypropylene. The product was characterized by several techniques, including FTi.r. and n.m.r., to provide evidence of the anhydride location on the chain. Several runs of varying catalyst concentration have shown that an optimum in anhydride incorporation onto the polypropylene exists. Examination of the system kinetics has shown that the overall order of the reaction remains second-order despite the presence of a catalyst. © 1997 Elsevier Science Ltd.