University/Industry Coop: Effect of Copolymer Structure on the Bulk and Microscopic Properties of Two-Phase Hydrogels (AMPP)

疏水修饰的水溶性聚合物在水溶液中经历自组装过程，疏水侧链聚集在一起形成具有特征尺寸和疏水性的胶束状聚集体或微域。所得到的网络被称为两相水凝胶，其物理性质与初始溶液完全不同，可以在许多应用中发挥良好的作用。在这项AMPP研究中，烷基取代聚丙烯酰胺合成了两相水凝胶，并探讨了聚合物结构与水凝胶性能之间的关系。重点是聚合物的三个结构性质，即总疏水含量、主链构象和疏水侧链的长度。研究了这些性能对微畴结构和组成以及块体材料流变性能的影响。这些独特材料最有趣的特点之一是分散的疏水相在水凝胶中吸收和保留有机溶质的能力，并以恒定速率将溶质释放到环境中（所谓的“零级释放”）。这种类型的释放轮廓在受控药物递送中备受追捧，这是制药领域非常感兴趣的新兴技术。控释剂型是在很长一段时间内以稳定的速率提供治疗水平的药物，消除了重复给药的需要，避免了药物血液水平波动的相关问题。这些新材料的基础研究将为药物控释用两相水凝胶的设计提供依据。这项工作将与埃克森研究与工程公司的同事合作进行，该公司也将提供研究中使用的聚合物。

Hydrophobically modified water-soluble polymers undergo a self-assembly process in aqueous solutions whereby the hydrophobic side chains cluster together into micelle-like aggregates, or microdomains, of characteristic size and hydrophobicity. The resulting network, which are called two- phase hydrogels, have physical properties which are completely different from those of the initial solution and which may be exploited to good effect in numerous applications. In this AMPP investigation, two-phase hydrogels from alkyl-substituted polyacrylamides are synthesized and the relationships between polymer structure and hydrogel properties are explored. The focus is on three structural properties of the polymer, namely, the total hydrophobe content, the backbone conformation, and the length of the hydrophobic side chains. The effects of these properties on the structure and composition of the microdomains and on the rheological properties of the bulk material are investigated. One of the most interesting features of these unique materials is the demonstrated ability of the dispersed hydrophobic phase to absorb and retain organic solutes within an aqueous gel, and to release the solutes to the surroundings at a constant rate (so-called "zero-order release"). This type of release profile is much sought after in controlled drug delivery, an emerging technology of great interest in the pharmaceutical field. A controlled release dosage form is one which delivers therapeutic levels of a drug at a steady rate over long times, eliminating the need for repeated doses of a medication and avoiding the associated problems of oscillating blood levels of the drug. The basic investigations on these novel materials will be used as the design basis for two-phase hydrogels for use in controlled drug release. This work will be conducted in collaboration with colleagues at Exxon Research and Engineering Company, who will also furnish the polymers to be used in the study.