Investigation of the morphology of biodegradable soft colloids

The aim of this project is to study the morphology of biodegradable soft colloids (microgels) made of hydroxypropyl cellulose (HPC). Stimuli-responsive microgels are of great interest for a variety of applications (functional coatings, viscosity modifiers, healthcare). For most processing needs (from injection to coatings), knowledge of the particle morphology is of utmost importance to tailor and predict the properties of dense suspensions and the interaction with interfaces. Un to now, the vast majority of fundamental and applied research focused on synthetic microgels. However, the growing interest in sustainability and biocompatibility calls for the development of novel “green” alternatives. We here focus on HPC, which allows synthesizing temperature-responsive particles that are biocompatible and biodegradable. To investigate their morphology, we plan to obtain form factors as a function of the synthesis protocols employed (reaction temperature and molecular weight), and compare them with monomer-resolved simulations from collaborators. We then plan to quantify the particle softness by using a recently introduced methodology to exert a controlled osmotic stress onto the microgels with partially deuterated linear polymers, using SANS with contrast variation to extrapolate the resulting microgels size. Overall, these results will be of fundamental importance in designing novel soft colloids that grant sustainable alternatives for the development of responsive materials.

本项目旨在研究以羟基丙基纤维素（hydroxypropyl cellulose, HPC）制备的可生物降解软胶体（微凝胶，microgels）的形貌。刺激响应型微凝胶在诸多应用场景中具备显著应用价值，涵盖功能涂层、粘度调节剂以及医疗健康领域。针对多数加工需求（从注射成型到涂层制备），掌握颗粒形貌对于定制并预测稠密悬浮液的性能，以及其与界面的相互作用均至关重要。迄今为止，绝大多数基础与应用研究均聚焦于合成型微凝胶。然而，随着社会对可持续性与生物相容性的关注度日益提升，亟需开发新型“绿色”替代方案。本研究聚焦于HPC体系，其可合成兼具生物相容性与可生物降解性的温度响应型颗粒。为探究此类颗粒的形貌，本研究计划获取与合成工艺参数（反应温度与分子量）相关的形状因子，并将其与合作方开展的单体分辨模拟结果进行对比。随后，本研究计划采用新近提出的方法量化颗粒的柔软性：该方法借助部分氘代线性聚合物对微凝胶施加可控渗透压力，并通过小角中子散射（small-angle neutron scattering, SANS）的对比度变化技术外推所得微凝胶的尺寸。总体而言，本研究结果对于设计新型软胶体、为响应性材料的开发提供可持续替代方案具有基础性重要意义。