New mechanisms for controlled polymer degradation and their incorporation into functional three-dimensional materials

在环境或人体中降解为小分子的聚合物引起了学术界和工业界的极大兴趣，其应用范围广泛，从包装到医疗器械。理想情况下，聚合物在发挥其功能时应高度稳定，但在所需条件下会迅速分解。目前可用的材料通常会因随机主链断裂而发生降解，并在各种环境中逐渐降解，从而限制了我们触发和控制这种降解的能力。拟议的研究计划旨在开发一类聚合物，该聚合物可通过端对端解聚机制特异性降解，以响应刺激响应端盖从聚合物末端的裂解。将开发出响应不同刺激的新端盖，例如氧化或还原物质浓度的变化、热、光甚至此类刺激的多种组合，从而增强我们对其降解行为的理解，并展示调整这些聚合物用于各种应用的潜力。通过仔细设计这些端盖，还将制备出由多个嵌段组成的聚合物。新单体的掺入将使聚合物的性能得到调整，进行进一步的化学衍生化，并引入药物掺入等新功能。 这些新的可解聚分子的最终功能将通过将其融入3维材料中来实现。嵌段共聚物将被纳入包括胶束和囊泡在内的纳米尺寸组件中，人们将探索它们以受控方式封装和释放抗癌药物、治疗性核酸和组织工程生长因子等物质的能力。这些聚合物还将用于制造用于组织工程细胞生长的多孔支架。只需改变端盖即可改变聚合物响应的刺激，这将在我们制备和研究响应不同刺激的各种新材料的能力方面提供比现有聚合物显着的优势。此外，在单一刺激介导的事件之后降解整个聚合物链的能力可以提供刺激的显着放大，使得材料特性的变化能够在低的、细胞相容的刺激浓度下发生。总的来说，这项研究将使我们对刺激响应材料的理解发生革命性的进步，同时为目标应用提供新的特性和功能。

Polymers that undergo degradation to small molecules in the environment or in the human body are of significant interest to both academia and industry for a wide range of applications from packaging to medical devices. Ideally, a polymer would be highly stable while performing its function, but would break down rapidly under the desired conditions. Currently available materials typically undergo degradation by random backbone scission and degrade gradually in a wide range of environments, limiting our ability to trigger and control this degradation. The proposed research program aims to develop a class of polymers that degrade specifically by an end-to-end depolymerization mechanism in response to the cleavage of a stimuli-responsive end-cap from the polymer terminus. New end-caps responsive to different stimuli such as changes in the concentrations of oxidizing or reducing species, heat, light and even multiple combinations of such stimuli will be developed, enhancing our understanding of their degradation behavior and demonstrating the potential to tune these polymers for a variety of applications. Through careful design of these end-caps, polymers composed of multiple blocks will also be prepared. The incorporation of new monomers will enable the properties of the polymers to be tuned, further chemical derivatization to be performed, and for new functions such as drug incorporation to be introduced. The ultimate functions of these new depolymerizable molecules will be realized through their incorporation into 3-dimensional materials. Block copolymers will be incorporated into nanometer-sized assemblies including micelles and vesicles, which will be explored for their ability to encapsulate and release cargo such as anti-cancer drugs, therapeutic nucleic acids, and growth factors for tissue engineering in a controlled manner. The polymers will also be used to fabricate porous scaffolds for the growth of cells for tissue engineering. The ability to change the stimuli to which the polymers respond, simply by changing the end-cap, will offer a significant advantage over the current polymers in terms of our ability to prepare and study a wide range of new materials responsive to different stimuli. Furthermore, the ability to degrade an entire polymer chain following a single stimulus-mediated event can provide a significant amplification of the stimulus, enabling changes in material properties to occur at low, cell-compatible stimulus concentrations. Overall, this research will enable transformative advancements in our understanding of stimuli-responsive materials while at the same time affording new properties and functions for the target applications.