Drug release studies of N-isopropyl acrylamide/acrylic acid grafted polypropylene nonwoven fabric

Radiation-induced graft copolymerization of N-isopropyl acrylamide (NIPAAm) and acrylic acid (AA) mixture was carried out on polypropylene (PP) nonwoven fabric to develop a thermosensitive material. The immobilization and release behaviour of 4-acetamidophenol onto the modified PP nonwoven fabric were studied. The effect of degree of grafting and temperature on the drug release behaviour was investigated. At 32 °C temperature, a small amount of drug was released, and a relatively large amount of drug still remained in the polymer matrix. However, when the release temperature was 40 °C (above the LCST of 37.5 °C), the drug release was greatly accelerated due to temperature induced structure changes of the grafted copolymer chains. It was also observed that the drug release was higher for samples with higher degree of grafting. At higher graft levels, the grafted chains are longer and form the hydrogel network which leads to the more efficient entrapment of the drug within the network on the surface and consequently, more drug tends to diffuse out as compared to the low graft levels. The resulting grafted membranes exhibited temperature-triggered drug release behavior, and have enormous potential for use as drug carriers.