(188u) pH-Temperature Sensitive N-Isopropylacrylamide Copolymer Microgels Formed by a Salt Bridge

pH-temperature sensitive microgels were prepared by mixing of poly(N-isopropylacrylamide-co-dimethylaminoethyl methacrylate) (P(NIPAM-co-DMAEMA)) and poly(N-isopropylacrylamide-co-methacrylic acid) (P(NiPAM-co-MAA)) at neutral conditions. They were investigated in terms of morphology, fourier transform infrared spectroscopy (FT-IR), and size. The pH-sensitive release property of microgels was observed in pH 4.0, 5.0, 6.0, 7.0, 8.0 and 9.0.The degree of release of microgels was almost 100% at acidic and alkali pHs. Because the microgels were disintegrated due to the loss of an electrostatic interaction between P(NIPAM-co-DMAEMA) and P(NIPAM-co-MAA) in acidic and alkali condition. Whereas, the release was suppressed because of strong elctrostatic interation of the P(NIPAM-co-DMAEMA) and P(NIPAM-co-MAA) at acidic pHs. The temperature-sensitive release property of microgels was observed at 25°C, 35°C and 45°C. Below lower critical solution temperature (LCST), the release of microgels was suppressed. Above LCST, the release was promoted possibly due to the thermal contraction of the P(NIPAM-co-DMAEMA) and P(NIPAM-co-MAA).