交联共聚丙烯酰胺-丙烯酸水凝胶溶胀态分子动力学的NMR弛豫研究

用反相悬浮聚合法制备了交联度分别为10％、7．5％、5％、1％、0．5％及0．25％的丙烯酰胺-丙烯酸P（AAM－NaAA）交联共聚水凝胶，用HNMR驰豫方法测定了水及聚合物主链上（－CH2CH－）基团中质子的自旋-自旋驰豫时间（T2），并结合质子线型分析，研究了交联凝胶在溶胀态下的内部分子运动，讨论了不同交联度下谱线线宽及驰豫变化的机制。结果表明，由于交联使凝胶内部各向异性相互作用增强，存在有残余的偶极-偶极相互作用，质子语具有特征的超Lorentz线型；质子线宽比非交联态时加大，水及主链的T2随交联度的加大而减小，反映了内部分子运动由强变弱的过程；水的T2驰豫不是单纯的单指数驰豫行为，表明凝胶内部有较强的键合束缚水存在，与DSC实验的结论一致。

NMR RELAXATION STUDIES ON THE DYNAMICS OF P(AAM-NaAA) COPOLYMER HYDROGELS

H NMR lineshape analysis and spin-spin relaxation measurements of seven .P (AAM-NaAA) copolymer hydrogels with different crosslink densities were carried out in order to elucidate the structure and dynamics of these copolyrner gels. The experiment results show that H NMR spectrum have a characteristic "superLorentzian" lineshape as a result of the residual dipolar interaction in gels. The T2 values of water and backbone protons were both found to decrease with increasing the degree of crosslinking. The spin-spin relaxation times, T2, of water included two components which implies there exists a bond state of water with fast spin diffusion in gels inaccordence with the previous DSC experiments in hydrogels.