Synthesis and characterization of poly(N-isopropyl acrylamide) copolymer with methoxy polyethyleneglycol monomethacrylate

초록

Poly(N-isopropyl acrylamide) copolymers with methoxy polyethyleneglycol monomethacrylate, poly (NIPAAm-co-MPEG), with different lengths of ethylene oxide (EO) units and mole% of MPEG were synthesized and characterized using FT-IR and H-1-NMR spectroscopy. The number of repeating units of EO were 6, 10, and 24. The amount of MPEG in the copolymers was in the range 1.0 similar to 10.0 mol%. The lower critical solution temperature (LCST) of a poly(NIPAAm-co-MPEG) strongly depends on the pH of its aqueous solution, especially for poly(NIPAAm-co-MPEG) samples having a high number of EO units. The LCST of the poly(NIPAAm-co-MPEG) samples shifted to higher temperature as both the number of EO units and the amount of MPEG increased. An increase in the number of EO units and the mole% of MPEG reflects an increase in the weight fraction of MPEG. The hydrophobic interactions of the NIPAAm units compete with the solubilizing and surface stabilizing effects of the MPEG units. The stabilizing effect is more pronounced upon increasing both the length of the EO units and the amount of MPEG. Therefore, an increase in the weight fraction of MPEG results in the LCST of the NIPAAm copolymers.

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