Gilcreest Vincent P, Dawson Kenneth A, Gorelov Alexander V
Chemistry Department, University College Dublin, Belfield, Dublin 4, Ireland.
J Phys Chem B. 2006 Nov 2;110(43):21903-10. doi: 10.1021/jp064112+.
The adsorption of N-isopropylacrylamide (NIPAM) based thermoresponsive polymers at the air-water interface was investigated by using drop and bubble shape tensiometry. The molecular weight dependence of polymer adsorption rate was studied by using narrowly distributed polymer fractions (polydispersity < 1.2) that were prepared by solvent:nonsolvent fractionation. The time-dependent surface tension profiles were fitted to the Hua-Rosen equation and the t values obtained were applied for interpretation of the kinetic data. It was found that the rate of polymer adsorption increased as the molecular weight of the polymer decreased. The relationship between polymer surface concentration and surface tension was determined by applying the pendant drop as a Langmuir-type film balance. From this relationship, the kinetics of polymer adsorption determined experimentally was compared with the adsorption rates predicted by a diffusion-controlled adsorption model based on the Ward-Tordai equation. The predicted adsorption rates were in good agreement with what was found experimentally. The dependence of the adsorption rate on the molecular weight of polymers can be satisfactorily described within the diffusion-controlled model.
通过液滴和气泡形状张力测定法研究了基于N-异丙基丙烯酰胺（NIPAM）的热响应性聚合物在气-水界面的吸附情况。使用通过溶剂：非溶剂分级制备的窄分布聚合物级分（多分散性<1.2）研究了聚合物吸附速率对分子量的依赖性。将随时间变化的表面张力曲线拟合到Hua-Rosen方程，并将获得的t值用于动力学数据的解释。结果发现，聚合物的吸附速率随着聚合物分子量的降低而增加。通过将悬滴用作朗缪尔型膜天平来确定聚合物表面浓度与表面张力之间的关系。根据这种关系，将实验测定的聚合物吸附动力学与基于Ward-Tordai方程的扩散控制吸附模型预测的吸附速率进行了比较。预测的吸附速率与实验结果吻合良好。在扩散控制模型中，可以令人满意地描述吸附速率对聚合物分子量的依赖性。
