Studies On Self-assembly Behavior Of Amphoteric Polyurethane

Amphoteric polyurethane (APU) is an amphoteric polyelectrolyte and also an amphiphilic block copolymer with hydrophobic soft segments such as N210,PTMG and PCL and pendent—COOH and—CH₂N(CH₃)₂ groups on the hard segments.This thesis took APU (prepard in our lab) as a model polymer, and studied the self-assembly behavior of APU in waterborne dispersions and the parameters related with the structure of the micelles at different temperature by DLS, SLS, fluorescent spectrophotometer,BIDNDC instrument and XPS, etc. APU with different hydrophobic segment was also synthesized and the properties varied with the temperature were studied.The studing results indicated that, during temperature get down from 25℃to 4℃, the Rh of micelles decreased because of the decreasing of the aggragate number. During this period, hydrophobic core, N210, became more hydrophilic, and this led to Rg/Rh decrease. When temperature rising, Rh and aggragate number were stable and we called it"the dynamically frozen micelles".We also discovered that systems with lower concentration such as 1mg/ml, 2mg/ml, Rh changed less when temperature varied, and when temperature rised to 60℃, HCl had become the bad solvent to APU and micelles attracted each other; this led to micelles caved in; so although Nagg was appreciably bigger than it at other temperatures, Rh was also decreased.To indicate the properties of APU in acid with varing temperature more advanced, we synthesized APU with different hydrophobic segment, and discovered APU with N210 hydrophobic segment anew self-assemble during temperature got down from 25℃to 4℃; Rh of APU with PTMG segement varied with temperature in the same direction, without"the dynamically frozen micelles"phenomenon; Rh of APU with PCl segement varied unconspicuous perhaps because of its rigidity.Besides, the experiment was also done to investigate I₁/I₃ of SDS/APU with time passed by fluorescence spectrum, and the adding formation which influenced I₁/I₃ was also studied by fluorescence spectrometer. The...