Collaborative Research: Microfabrication and Self-Assembly of Shape-Changing Hydrogels with Chromonic Liquid Crystalline Order

合作研究：彩色液晶有序变形水凝胶的微加工和自组装

基本信息

批准号：
1662113
负责人：
M Ravi Shankar
金额：
$ 14.32万
依托单位：
University of Pittsburgh
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-09-01 至 2022-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1662113&HistoricalAwards=false
关键词：
Collaborative Research Microfabrication Self Assembly

项目摘要

Shape-changing liquid crystal hydrogels are soft, rubbery materials that can perform mechanical work as "artificial" muscles, without motors, joints, or control systems. They move spontaneously in response to slight temperature changes, and can be designed to flex in different geometries. This collaborative research effort focuses on developing techniques to engineer these materials to produce novel devices such as self-cleaning surfaces. Like the cilia that sweep contaminants from human lungs, surfaces will be coated with micro-scale hydrogel structures that move as temperature fluctuates. These novel active coatings will address a critical need for self-cleaning devices in healthcare applications, and could prevent bacterial contamination that leads to frequent infections and thousands of deaths annually in the United States. In addition, community outreach efforts will be designed that engage young students and will help to broaden the diversity of the technical workforce, and research internships will help prepare high school students for advanced studies in science and engineering. Smart, programmable materials that respond mechanically to environmental stimuli are needed for smart biomedical devices. Hydrogels with chromonic liquid crystalline order are of interest for such applications because they morph anisotropically in response to biologically-benign temperature changes, and because their actuation trajectory can be programmed by patterning the material's molecular alignment. A key challenge is to fabricate such complex actuators at length scales too small to access via 3D printing and in shape profiles that are not flat films. This award supports development of novel techniques for design and microfabrication of shape-morphing hydrogels, using hierarchical patterning of molecular orientation achieved by combining soft lithography and liquid crystal self-assembly. This fundamental research will test the hypothesis that the shape of soft lithography molds can be used to pattern molecular alignment in micro-scale structures made of chromonic liquid crystal hydrogels, and that these aligned hydrogels can undergo programmable actuation in response to biologically-benign temperature changes. This processing approach will be used to create artificial cilia-like structures. Experimental efforts will be closely coupled to theory/simulation at two levels. First, the molecular order (nematic director) arising from surface anchoring from the soft lithography mold and liquid crystal chirality will be modeled. Second, nonlinear finite element elastodynamics simulations will be used to model shape evolution of active hydrogel micro-devices with a given director field as they transform under stimulus. This collaborative project brings together a multidisciplinary team with complementary expertise in responsive materials chemistry, materials modeling, and mechanical design.

改变形状的液晶水凝胶是柔软的橡胶材料，可以作为“人造”肌肉进行机械工作，而无需电动机，关节或控制系统。它们会自发地响应轻微的温度变化而自发移动，并且可以设计用于不同几何形状的弯曲。这项协作研究工作着重于开发技术来设计这些材料，以生产新的设备，例如自我清洁表面。就像从人肺中扫除污染物的纤毛一样，表面将涂有微尺度水凝胶结构，随着温度的波动而移动。这些新型的活跃涂层将解决医疗保健应用中自我清洁设备的关键需求，并可以防止细菌污染，从而导致每年在美国频繁感染和数千人死亡。此外，将设计社区推广工作，使年轻学生吸引年轻学生，并将有助于扩大技术劳动力的多样性，研究实习将有助于为高中生准备科学和工程学的高级研究。智能生物医学设备需要机械地对环境刺激的机械响应的智能，可编程的材料。具有染色性液体晶体顺序的水凝胶对于此类应用而言是感兴趣的，因为它们会响应生物学的温度变化而在各向异性上变形，并且由于可以通过对材料的分子比对来编程它们的致动轨迹。一个关键的挑战是在太小的长度上制造这种复杂的执行器，无法通过3D打印和不是扁平膜的形状轮廓访问。该奖项支持通过将软光刻和液晶自组装相结合而实现的分子方向的层次模式，以开发形状变形水凝胶的新技术和微结构。这项基本研究将检验以下假设：软光刻霉菌的形状可用于模拟由染色体液体晶体水凝胶制成的微尺度结构中的分子比对，并且这些排列的水凝胶可以响应生物学温度变化而进行程序化的驱动。这种加工方法将用于创建人工纤毛样结构。实验工作将与两个级别的理论/模拟紧密耦合。首先，将模拟由软光刻霉菌和液晶性手性锚定表面锚定的分子阶（列表导演）。其次，非线性有限元弹性动力学模拟将用于模拟活性水凝胶微设备在刺激下转换时的活性水凝胶微设备的演变。这个协作项目汇集了一个多学科团队，具有响应材料化学，材料建模和机械设计方面的互补专业知识。