Mesoporous Hydrogels from Microemulsions and Similar Structures for Hydrogel-based Sensors

来自微乳液的介孔水凝胶和用于水凝胶传感器的类似结构

• 批准号: 382408767
• 负责人: Professor Dr.-Ing. Gerald Gerlach
• 金额: --
• 依托单位: Leibniz-Institut für Polymerforschung Dresden (IPF)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/382408767?language=en
• 关键词: Mesoporous; Hydrogels; Microemulsions; Similar; Structures

Hydrogels are crosslinked polymers with the ability of uptaking huge amounts of water. This characteristic behavior leads to an increase of the hydrogel volume. Thus, hydrogels are the proper materials for applications in sensors and actuators, especially since hydrogels can be employed for utilization in micro systems.The swelling of huge hydrogel volumes results in detectable forces which can either be measured by means of a sensor or work as actuator components. However, the diffusion properties of water and chemical species in the crosslinked polymer structure of the hydrogel affect the response characteristics. Hence, high sensitivity often goes along with long response times.A solution may be the employment of porous hydrogels which can accelerate the cooperative diffusion process. Porous hydrogels in hydrogel-based piezoresistive pH sensors showed remarkable improvements in our previous works. Here, the response time of a pH sensor based on an acrylic acid/acrylamide based hydrogel was reduced considerably. Also, the swelling degree of the hydrogel increased noticeably. However, the sensitivity of the sensor decreased due to a decreased stiffness of the hydrogel. For this previous work, porous layers were synthesized by using porogens which cause a phase separation during polymerization. The use of porogens yields materials with macroporosity. Due to the synthesis method, the adjustment of pore sizes and pore size distribution is insufficient though.A possible route for synthesizing hydrogel layers with defined pore geometry is a template method described as follows. Mixtures of organic phase, water and surfactant are prepared. Stable, transparent solutions with defined aggregate structures (micelles, cylindrical micelles, bicontinuous, lamellae, hexagonal and cubic phases) occur at certain compositions. By dissolving monomers or polymers in the aqueous or organic phase of the template solution, the aggregate structures can be used as templates for the synthesis of mesoporous hydrogels with different morphologies.By using this method, firstly, the template is defined before polymerization. Secondly, replacement of macropores with mesopores leads to a higher hydrogel volume in the total volume of the hydrogel layer. For these reasons, this template method can evolve to be the preferred route to produce fast-responsive and sensitive hydrogels for microsystems technology.

水凝胶是交联聚合物，能够吸收大量的水。这种特征行为导致水凝胶体积的增加。因此，水凝胶是适用于传感器和执行器的材料，特别是因为水凝胶可用于微系统。巨大水凝胶体积的膨胀会产生可检测的力，该力可以通过传感器测量或用作执行器组件。然而，水凝胶交联聚合物结构中水和化学物质的扩散特性影响响应特性。因此，高灵敏度通常伴随着长响应时间。解决方案可能是使用多孔水凝胶，它可以加速协同扩散过程。基于水凝胶的压阻式 pH 传感器中的多孔水凝胶在我们之前的工作中显示出显着的改进。在此，基于丙烯酸/丙烯酰胺水凝胶的pH传感器的响应时间显着缩短。此外，水凝胶的溶胀度显着增加。然而，由于水凝胶的硬度降低，传感器的灵敏度降低。对于这项先前的工作，多孔层是通过使用致孔剂合成的，致孔剂在聚合过程中引起相分离。使用致孔剂可产生具有大孔隙的材料。然而，由于合成方法的原因，孔径和孔径分布的调整是不够的。合成具有限定的孔几何形状的水凝胶层的可能途径是如下所述的模板方法。制备有机相、水和表面活性剂的混合物。在某些组成下会出现具有确定聚集结构（胶束、圆柱形胶束、双连续相、片状相、六方相和立方相）的稳定、透明的溶液。通过将单体或聚合物溶解在模板溶液的水相或有机相中，聚集体结构可以用作合成不同形貌介孔水凝胶的模板。采用该方法，首先在聚合前定义模板。其次，用中孔代替大孔导致水凝胶层总体积中的水凝胶体积更高。由于这些原因，这种模板方法可以发展成为为微系统技术生产快速响应和敏感水凝胶的首选途径。