Weng Lihui, Chen Xuming, Chen Weiliam
Department of Biomedical Engineering, State University of New York-Stony Brook, Stony Brook, New York 11794-8181, USA.
Biomacromolecules. 2007 Apr;8(4):1109-15. doi: 10.1021/bm0610065. Epub 2007 Mar 15.
The gelation kinetics of an in situ gelable hydrogel formulated from oxidized dextran (Odex) and N-carboxyethyl chitosan (CEC) was investigated rheologically. Both Schiff base mediated chemical and physical crosslinking account for its rapid gelation (30-600 s) between 5 and 37 degrees C. The correlation between gelation kinetics and hydrogel properties with Odex/CEC concentration, their feed ratio, and temperature were elucidated. The gelation time determined from crossing over of storage moduli (G') and loss moduli (G' ') was in good agreement with that deduced from frequency sweeping tests according to the Winter-Chambon power law. The power law exponents for a 2% (w/v) Odex/CEC solution (ratio 5:5) at the gel point was 0.61, which is in excellent agreement with the value predicted from percolation theory (2/3). Temperature dependence of gelation time for the same hydrogel formulation is well-described by an Arrhenius plot with its apparent activation energy calculated at 51.9 kJ/mol.
对由氧化葡聚糖（Odex）和N-羧乙基壳聚糖（CEC）配制而成的可原位凝胶化水凝胶的凝胶化动力学进行了流变学研究。席夫碱介导的化学交联和物理交联共同导致了其在5至37摄氏度之间的快速凝胶化（30 - 600秒）。阐明了凝胶化动力学与水凝胶性质之间与Odex/CEC浓度、它们的进料比以及温度的相关性。由储能模量（G'）和损耗模量（G''）交叉点确定的凝胶化时间与根据Winter-Chambon幂律从频率扫描测试推导得出的结果高度一致。在凝胶点处，2%（w/v）的Odex/CEC溶液（比例为5:5）的幂律指数为0.61，这与渗流理论预测的值（2/3）非常吻合。相同水凝胶配方的凝胶化时间的温度依赖性通过阿伦尼乌斯图得到了很好的描述，其表观活化能计算为51.9 kJ/mol。
