Preparation of conjugated p-aminobenzamidine on thermosensitive poly(NIPAM) by irradiation grafted process

A thermosensitive polymer that can either be soluble or insoluble in water was synthesized by electron beam irradiation N-isopropylacrylamide (NIPAM) and -mercaptopropionic acid (MPA) without the presence of initiator. The polymer was then reacted with p-aminobenzamidine (PABA) using water-soluble carbodiimide (WSC) to introduce an affinity ligand. Radiation grafting of poly(NIPAM) and conjugation of ligand was successfully completed. It was found that the graft reaction could be done at higher dose and carboxyl group was introduced during irradiation of samples in air. Production and precipitate of the carboxylated poly(NIPAM) were investigated. Some results of direct radiation polymerization in this system are also given. The effect of radiation characteristics such as irradiation dose on the lower critical solution temperature (LCST) and conjugation of PABA on the prepared poly(NIPAM) has also been investigated. The precipitate of the grafted polymer has thermal sensitivity and their LCST is close to 35C.