(181bf) Development of Covalent and Non-Covalent Crosslinked Temperature Responsive Polymeric Gels

Poly (N-isopropylacrylamide) (PNIPAAm) is a well-known temperature responsive polymer and has received extensive attention due to its sharp transition from hydrophilic to hydrophobic at its lower critical solution temperature (LCST). In this research, novel covalent crosslinked and non-covalent crosslinked polymers have been synthesized with biphenyl functionalities, and their unique properties were characterized.

The overall goal of this project was to develop polymers that incorporate a biphenyl moiety, which can be used to physically crosslink the system with pi-pi stacking interaction, and also, to introduce a covalent crosslinker to examine the combined effects of the covalent and non-covalent crosslinkers. The monomers used were N-isopropylacrylamide (NIPAAm) and the acrylated forms of 4-phenylphenol and 2-phenylphenol, which are identified as 4PPMA and 2PPMA. With these monomers, physically crosslinked systems were synthesized and characterized for their molecular weight, swelling and mechanical properties. The crosslinker, which is the acrylated form of 4,4-dihydroxybiphenyl (44BDA), was then introduced and again the swelling and mechanical properties were characterized.