Swelling-controlled solute diffusion in glassy polymers

玻璃态聚合物中的渗透传递在传统的工程应用中起着重要作用，如膜、包装和阻隔材料。最近，这种现象在从微米和纳米纤维到用于药物递送的溶胀控制水凝胶的设计的应用中变得越来越重要。在后一种情况下，大量体积溶胀和截留溶质的扩散的存在可能进一步使总速率过程复杂化。这种膨胀和扩散通常不遵循菲克扩散机制。尽管已经广泛地研究了玻璃态聚合物中单一渗透剂传输的情况，但是还没有适当地研究聚合物中初始溶质浓度水平对溶剂渗透特性的影响，并且溶胀过程与所观察到的溶质从玻璃态聚合物，特别是水凝胶，提出的研究的长期目标是充分阐明溶质和溶剂在玻璃态聚合物中的传输机制。我们的近期目标是阐明样品尺寸和几何形状以及初始溶质浓度对异常渗透输运的影响，并深入了解经历广泛溶剂溶胀的玻璃态聚合物中溶质扩散的动力学。拟议研究的结果将为通常被忽视的局部溶质浓度对渗透输运特性的影响带来新的见解，并提供关于溶剂溶胀对从玻璃状聚合物中释放溶质的动力学的影响的结论性解决方案。所获得的信息将是至关重要的玻璃状聚合物的设计和选择的应用范围从微米和纳米纤维到药物输送。

Penetrant transport in glassy polymers has played a major role in traditional engineering applications such as membranes, packaging and barrier materials. More recently, this phenomenon has become increasingly important in applications ranging from micro and nanofabrication to the design of swelling-controlled hydrogels for drug delivery. In the latter case, the presence of a substantial volume swelling and the diffusion of entrapped solute may further complicate the overall rate process. Such swelling and diffusion generally do not follow a Fickian diffusion mechanism. Although the case of a single penetrant transport in glassy polymers has been studied extensively, the effect of initial solute concentration level in the polymer on the solvent penetration characteristics has not been properly studied, and the role of the swelling process in relation to the observed solute release behaviour from glassy polymers, in particular hydrogels, has not been conclusively resolved.The long-term objective of the proposed research is to fully elucidate the mechanisms of solute and solvent transport in glassy polymers. Our immediate objective is aimed at elucidating the effect of sample size and geometry as well as initial solute concentration on anomalous penetrant transport, and gaining an in-depth understanding of the kinetics of solute diffusion from glassy polymers undergoing extensive solvent swelling.The results from the proposed research will bring new insights into the generally overlooked effect of local solute concentration on the characteristics of penetrant transport, and provide conclusive resolution regarding the effect of solvent swelling on the kinetics of solute release from glassy polymers. Information gained will be of critical importance to the design and selection of glassy polymers for applications ranging from micro and nanofabrication to drug delivery.