Development of high functionality composites and nanocomposites for tissue engineering and energy conversion systems

在过去的十年里，功能纳米复合材料将在包括氢燃料电池、太阳能电池、组织工程等可持续能源技术在内的各个领域发挥关键作用。它们可以提供相应的块体材料无法达到的性能。目前的重点是针对其特定的应用对其组成、形态、纳米结构和功能进行控制。这项拟议的研究计划的目标是开发可控的形态/功能纳米复合材料和生物相容性复合材料，特别设计用于染料敏化太阳能电池(DSSC)光阳极、质子交换膜燃料电池(PEMFC)电极和双极板(BPP)，以及用于软骨组织再生的生物相容性支架。 目前，软骨多孔支架一旦被开发出来，需要进一步的溶剂处理，在孔内添加生物相容性材料，以促进细胞增殖，导致不需要的残留溶剂。在这方面，我们首先提出 以无溶剂技术为主题开发开放式细胞支架，其中生物相容/可生物降解的壳聚糖 在支架发泡过程中，天然聚合物被改性并直接投射到毛孔表面，由于壳聚糖的改性，导致了强大的粘附性。 传统的DSSC光阳极二氧化钛(TiO2O2TiO2O4)层制备工艺需要高温烧结，导致结构脆性。因此，本提案第二个主题的目标--灵活结构的发展是一项挑战。基于我们在纳米结构二氧化钛合成方面的专业知识，我们将利用室温静电纺丝技术，从含有尺寸和形状可控的二氧化钛-硫化镉纳米颗粒的聚合物基质中开发出柔性纤维纳米结构。主要目的是通过提供更大的光阳极表面积和增加光敏化染料的电子转移来增加光阳极的灵活性和电池的效率。 作为本建议的第三个研究主题，我们将使用最近设计的与我们的ARES流变仪兼容的实验装置来研究共连续形态纳米复合材料中关于其结晶动力学的电导行为的在线演变。这将有助于我们优化纳米复合材料的冷却轮廓，以获得更高的电导率。我们还将进行一项原创性的研究，在该研究中，我们将研究动态剪切对熔融聚合物/聚合物体系导电性的影响。通过这项研究，我们的目标是降低导电添加剂的阈值浓度，从而提高纳米材料的加工性和导电性，特别是聚合物基PEMFC电极和BPP所需的纳米材料。

During the last decade, functional nanocomposites are set to play a crucial role in various areas including sustainable energy technologies such as, hydrogen fuel cells, solar cells, tissue engineering, etc. They can offer performances that are not reachable by their corresponding bulk materials. The emphases are presently placed on the control of their composition, morphology, nanostructure and functionality with respect to their specific applications. The aim of the proposed research program is to develop controlled morphology/functionality nanocomposites and biocompatible composites particularly designed for dye-sensitized solar cell (DSSC) photoanodes, proton exchange membrane fuel cells (PEMFC) electrodes and bipolar plates (BPPs), and biocompatible scaffolds for cartilage tissue regeneration. Presently, cartilage porous scaffolds, once developed, need a further solvent treatment to add biocompatible materials inside the pores in order to promote cell proliferation, leading to unwanted residual solvents. We propose in this first theme a solvent-free technique to develop open cell scaffolds where chitosan, a biocompatible/biodegradable natural polymer, is modified and directly projected on the surface of the pores during scaffolds' foaming, leading to strong adhesion thanks to chitosan modification. The conventional manufacturing process of Titanium dioxide (TiO2) layer in DSSC photoanode requires a high temperature sintering, leading to a brittle structure. Then the development of flexible structures, object of the second theme in this proposal, is a challenge. Based on our expertise in the synthesis of nanostructured TiO2, we will use room temperature electrospinning technique to develop flexible fibrous nanostructures from a polymeric matrix containing TiO2-CdS nanoparticles of controlled size and shape. The main objective is to increase photoanode flexibility and cell efficiency by providing large photoanode surface area and increased electron transfer with the photosensitizing dye. As third research theme in this proposal, we will use a recently designed experimental setup compatible with our ARES rheometer in order to investigate the 'online' evolution of the electrical conductivity behavior in co-continuous morphology nanocomposites with respect to their crystallization kinetics. This will help us to optimize the cooling profile of the nanocomposites in order to attain higher electrical conductivity. We will also undergo an original study in which we will investigate the effect of dynamic shearing on the electrical conductivity of melted polymer/polymer systems. We aim from this study to decrease the threshold concentration of the conductive additives and consequently increase nanomaterials' processability and electrical conductivity, particularly needed for polymer-based PEMFC electrodes and BPPs.