Modification and characterization of novel polymeric surfactants

Abstract

Poly (ethylene oxide)-poly (propylene oxide)-poly (ethylene oxide) (PEO-PPO-PEO) triblock copolymers (Pluronic F127) have been extensively studied because of their thermal responsive aggregation behavior that can be used for a variety of biomedical applications. On top of its unique surfactant behavior, its low toxicity and minimal immune response also make this polymer highly attractive for such application. In this work, the objective is to incorporate the thermal responsive aggregation behavior of such a polymer into another water-soluble, biocompatible and relatively amphiphilic polymer, polyvinyl pyrrolidone (PVP). This is achieved by grafting of the PVP on PEO-PPO-PEO triblock copolymers. This modified polymer with both thermal responsiveness and remarkable capacity to interact with a wide variety of hydrophilic and hydrophobic pharmaceutical agents is very attractive for medical applications. These novel graft copolymers were synthesized by free-radical polymerization. Polymerization conditions such as types of initiators, concentrations of reactants, reaction times and temperatures, are critical to obtain the graft copolymers with high grafting efficiency. It is found that ideal feeding ratio, reaction time and reaction temperature are 2.5, 6 hours and 70 C respectively. PVP was also grafted onto either PEO block (F127(PEO)-g-PVP) or PPO block (F127(PPO)-g-PVP) of F127 successfully. The copolymers were characterized by means of infrared spectroscopy, gel permeation chromatography and nuclear magnetic resonance spectroscopy. The structures, molecular weights and molecular weight distribution of three kinds of graft copolymers, which are F127-g-PVP, F127(PPO)-g-PVP and F127(PEO)-g-PVP, have been obtained and verified. ATTENTION: The Singapore Copyright Act applies to the use of this document. Nanyang Technological University Library