SURFACE MODIFICATION OF POLYPROPYLENE BY A COMBINATION OF PHOTOOXIDATION AND PHOTOSUBSTITUTION REACTIONS

An efficient photoprocess has been developed to increase polypropylene surface wettability by insertion of acid, ester, and amide functionalities. A systematic study of polypropylene surface irradiations indicates that photooxidations always precede the photosubstitution reactions that occur at the carbonyl site to form carboxyl, ester, and amide groups. Irradiations with amines to form amide groups always achieved the highest level of wettability improvement without changing bulk morphology. This process may be very beneficial in facilitating the fabrication of composite membranes with hydrophilic barriers an top of a hydrophobic polymeric support such as polypropylene. The high chemical resistance of polypropylene matrix to various solvents makes the partially hydrophilized polypropylene an ideal membrane support when hydrophilic membrane barriers made by interfacial polymerization/crosslinking are needed for a variety of separation applications. (C) 1995 John Wiley and Sons, Inc.