Macromolecular-bottlebrush polymeric gels with tissue-mimetic swelling and mechanical properties

非技术性SUMMARY活组织的独特之处在于，它们能够在几乎恒定的含水率下无缝跨越一系列机械特性，从超软的大脑到超坚韧的软骨。相反，合成的组织类似物(即聚合物凝胶)目前无法在不影响其机械性能的情况下控制水分的量。本文提出了一种基于瓶刷-大分子结构的新型聚合物材料，以实现对凝胶组成和力学性能的独立和可编程控制。与传统的线性聚合物不同，瓶刷结构引入了无数的侧链或“刷毛”，提供了额外的分子参数来调节柔软度，而不会改变水分含量。此外，定制侧链末端的化学成分将使新的应用得以实现，例如可编程和可注射材料，用于组织模拟设备的添加制造。拟议的新型聚合物凝胶将通过整合尖端聚合物化学、软物质物理和新兴技术为跨学科研究提供充足的机会，这些技术可能会在许多应用领域取得突破，如生物医学设备、组织工程支架和软机器人。技术总结该项目将解决三个根本挑战。首先，平衡溶胀比和凝胶的力学性能将分别与刷状网络结构参数(如侧链长度和接枝密度)相关联。建筑-膨胀-力学相互关系的三角测量将提供对膨胀、柔软和非线性力学响应的独立控制。例如，这将产生一系列史无前例的合成凝胶，它们具有相同的溶剂含量，但模数在几个数量级内变化很大。第二个目标是设计刷状介孔，以实现组织模拟弹性体的无溶剂注射。挑战是将固化时间控制在几秒到几天之间，与完全固化的聚合物网络的机械性能分开。最后，目标1和目标2的成功实施将使一种基于热敏水凝胶的新型生物墨水材料成为可能，这种材料可以注射和3D打印具有明确溶剂分数和机械性能的物体。这里的主要挑战是将印刷材料的受控温度凝胶与目标1和2中追求的按建筑进行设计的目标相结合。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARYLiving tissues are distinct in their ability to seamlessly span a range of mechanical properties from ultra-soft brain to super-tough cartilage at nearly constant water fraction. On the contrary, synthetic analogs of tissues (i.e. polymeric gels) are currently not capable to control the amount of water without affecting their mechanics. A new class of polymeric materials based on bottlebrush-macromolecular architectures is proposed here to enable independent and programmable control over gel composition and mechanical properties. In contrast to traditional linear polymers, the bottlebrush architecture introduces a myriad of side chains or “bristles” that afford additional molecular parameters to tune softness without changing the water fraction. Furthermore, tailoring the chemistry of side-chain ends will empower novel applications such as programmable and injectable materials for additive manufacturing of tissue-mimetic devices. The proposed novel class of polymeric gels will provide ample opportunities for interdisciplinary research through integration of cutting-edge polymer chemistry, soft-matter physics, and emerging technologies that may lead to breakthroughs in many applications such as biomedical devices, tissue-engineering scaffolds, and soft robotics. TECHNICAL SUMMARYThe project will address three fundamental challenges. First, the equilibrium swelling ratio and gel’s mechanical properties will be separately correlated with architectural parameters of brush-like networks such as the side chain length and grafting density. Triangulation of architecture-swelling-mechanics correlations will afford independent control over swelling, softness, and non-linear mechanical response. For example, this will create an unprecedented series of synthetic gels with the same solvent fraction, but widely different moduli varying within several orders of magnitude. The second goal is to design brush-like mesoblocks that enable solvent-free injection of tissue-mimetic elastomers. The challenge is to control curing time from seconds to days separate from mechanical properties of fully cured polymer networks. Lastly, successful implementation of goals 1 and 2 will enable a new class of bioink materials based on thermosensitive hydrogels that can inject and 3D-print objects with well-defined solvent fractions and mechanical properties. The main challenge here is to integrate controlled-temperature gelation of printed materials with the design-by-architecture objectives pursued in goals 1 and 2.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.