远程多重响应聚合物微米尺度自折叠薄膜

Polymer self-folding films at microscale have potential applications in biomedical fields, since they can switch from 2D shapes into 3D ones under different stimulus. The most widely accepted films are based on bilayered structures, in which the active layer could shrink or expand under the stimulus. Such movement is restricted by the attaching inert layer, through which the overall transformation occurs. At present, several drawbacks limit the further applications of polymer self-folding films, which need to be improved and are listed as follow. (1) Few polymers can integrate biocompatibility, biodegradation and stimulus-responsibility in one single material. (2) Biomedical substances are vulnerable to the reported high temperature or low pH value as the stimulus. (3) The investigated switching manner is mainly focused on uniform folding rather than complicated ways. Therefore, we propose a novel polymer self-folding films at microscale, which could switch from 2D to 3D structures in a uniform or gradient manner under the alternative magnetic field and near-infrared light. Stimuli-responsive heat build-up nanoparticles will be filled into one side of the biocompatible and biodegradable shape-memory polymers films as the active layer. Such polymer bilayered films will be fabricated and programmed at microscale. The polymer and functional particle systems will be adjusted, while the structures of the bilayer films will be controlled by the particle distribution. The observed structure-property-folding manner relations will be explained by the temperature and modulus distribution in the bilayer films. And finally, based on such studies, the properties and folding manners of the polymer self-folding films will be optimized and controlled.

聚合物微米尺度自折叠薄膜在外场激发下可由二维形状变成三维形状，因此在生物医药领域有着应用前景。实现自折叠的机理主要是基于双层薄膜结构：在外场激发下发生收缩或膨胀的活性层受到惰性层限制，从而带动薄膜发生整体形变。目前该领域研究存在以下不足：活性层材料很难兼具生物相容性、可降解性和刺激响应性；接触式激发方式难以用于应用领域；且薄膜变形模式比较均一。因此，本项目基于具有生物相容性和降解性的形状记忆聚合物，通过在其薄膜一侧填充具有远程响应生热功能的纳米粒子作为活性层，并实现微米尺度上双层薄膜的制备以及临时形状赋予，得到一种可同时响应交变磁场与近红外光照射激发的、能够均匀或渐次形变并二次展开的新型聚合物自折叠薄膜。本项目将调节聚合物材料和功能填料体系，调控粒子分布来设计薄膜内部结构，通过薄膜内部温度和模量分布解释结构与性能、形变之间的关系，从而实现对自折叠薄膜的性能优化和形变行为控制。

聚合物自折叠薄膜是一种具有独特变形能力的新型聚合物薄膜材料。它可以根据外界环境变化改变自身形状，由简单的二维平面结构变形成复杂的三维结构。这种新型聚合物薄膜材料在细胞包覆和药物释放等生物医药领域，以及宏观驱动或自适应折叠装置等其它领域具有广泛应用前景，因此近年来获得越来越多的关注。通过远程激发聚合物自折叠薄膜发生复杂的形状变化则是该领域所需重点关注的内容。..本课题首次开发了一系列稀土有机配合物(Yb(TTA)3Phen, Nd(TTA)3Phen, Yb(TTA)2AAPhen, Nd(TTA)2AAPhen, Sm(TTA)3Phen)作为针对近红外光(980, 808和1064nm)的选择性光热填料，分别通过物理混合或化学键合等方式制备相应的形状记忆聚合物复合材料，并详细研究了有机配合物对复合材料结构与性能的影响。并通过含有不同配合物的复合材料的组装，实现了微米尺度表面图案、微米厚度聚合物薄膜在不同近红外光照射下的选择性形状回复，实现了远程激发下聚合物薄膜的复杂形状变化。并最终通过进一步引入紫外光响应的主链含有偶氮苯基团的聚氨酯、以及532nm可见光响应的金纳米粒子，实现了能够响应5种波段的聚合物薄膜材料的制备。..还首次将稀土有机配合物(Yb(TTA)2AAPhen, Nd(TTA)2AAPhen，Sm(TTA)2AAPhen)通过化学键合的方式制备了智能水凝胶复合材料，研究了材料的结构与性能，并探究了其在微通道、可控释放、和自折叠薄膜领域的应用；为了同时提高水凝胶的力学性能，本工作还制备了Sm(TTA)Phen(NO3)3, 并利用NO3基团与水凝胶中羧基的氢键作用对水凝胶基体进行有效增强，最终得到了高力学性能、高荧光特性、和智能光响应的水凝胶材料。..本课题同时使用了上转换材料首次将上转换材料NaYF4:99.5%Yb3+, 0.5%Tm3+引入到SMP体系中，通过NaYF4的上转换特性和光热效应实现了对材料特定位置的准确激发；本项目还开展了一系列光响应自修复涂层工作。..本课题的实施有助于聚合物薄膜在不同波段光波照射下实现更为复杂的形状变化，同时由于近红外光的安全性和穿透性，使其在生物医药和柔性执行器等领域具有广阔的应用前景。