PDMAEMA多重环境响应行为的NMR研究

利用原子转移自由基聚合（Atom Transfer Radical Polymerization, ATRP）合成了分子量分布较窄的聚甲基丙烯酸N, N-二甲氨基乙酯{Poly[2 (diethylamino)ethylmethacry-late], PDMAEMA}并通过对液体核磁共振氢谱（¹H NMR）化学位移以及弛豫时间（T₁、T₂）的测量，研究了聚合物PDMAEMA的温度敏感、pH敏感以及离子敏感3种环境敏感行为. 发现聚合物链段的运动性，以及温度和离子强度诱导的相变行为，都与体系的pH值具有强依赖关系. 室温下，聚合物链段的运动性随pH值的增大而降低. 酸性条件下，聚合物表现出离子敏感性，而不表现出温度敏感性. 碱性条件下，聚合物表现出温度敏感性，不表现出离子敏感性.

NMR Study on Multiple Environmental Response Behaviors of Poly[2- (diethylamino) ethylmethacry-late] (PDMAEMA)

Poly[2-(diethylamino)ethylmethacry-late](PDMAEMA) with narrow molecular-weight distribution was synthesized by the atom transfer radical polymerization(ATRP) method.The thermo-sensitive,pH-sensitive and ionic-sensitive behaviors of PDMAEMA chains in D2O solution were investigated by measuring 1H NMR spectra and relaxation times.It was found that the mobility,temperature-induced lower critical solution temperature(LCST) transition and ionic-strength-induced phase separation of PDMAEMA chains depend on pH of the solution.The mobility of PDMAEMA chains decreased with increasing pH value at room temperature.Ionic-strength-induced phase separation was observed at lower pH values,but not LCST transition.On the contrary,the LCST transition occurred at higher pH values,but not the ionic-strength-induced phase separation.