薄膜表面微细结构直接热辊连续成形的介观尺度效应及控形控性新方法

Surface microstructures in meso scale (10-500μm) can enhance the conversion efficiency of polymer solar cells by 40% and improve the light extraction efficiency of flexible displays twice. However, large-scale application of thin film optoelectronics products is currently limited by low efficiency of photoetching process and poor consistency of ultraviolet imprint lithography. This proposal put forward a novel hot roll to roll forming process to fabricate meso-scale microstructures directly on thin film polymer substrate by integrating the advantages of hot moulding process and roll to roll motion in order to improve the efficiency and quality. Firstly, the influence of structural scale on material flow behavior will be quantificationally described and an analytical method of polymer rheological behavior considering size effect will then be established by developing meso-scale material constitutive model and friction model. Then, a numerical model of hot roll to roll forming process considering size effect will be built to systematically investigate the impacts of processing parameters on forming accuracy and performance consistency of microstructures. Thereby, an integrative method of dimensional and physical control will be developed to fabricate meso-scale microstructures on thin film substrate. Finally, the hot roll to roll forming mechanism for microstructures and the coordinated control system of the multi-roll will be intensively studied. A roll to roll forming prototype for meso-scale microstructures will be set up and experimental methods of microstructures manufacturing on thin film polymer will be established. As a result, the fulfillment of this proposal will make great contribution, including materials, process and equipments, to meso-scale microstructures manufacturing on thin film polymer substrate with dimensional and physical control.

介观尺度（10-500μm）表面微细结构可使聚合物薄膜太阳能电池性能提高40%、柔性显示器出光率提高一倍以上，目前的光刻工艺效率低、紫外固化压印工艺质量一致性差，阻碍着薄膜光电产品大规模应用。本项目通过热模压工艺与卷对卷运动方式的复合，提出聚合物薄膜微细结构直接热辊压连续成形成性新方法，实现微细结构高效高质量加工。建立介观尺度下材料本构模型和摩擦模型，定量描述结构尺度对材料流变行为的影响规律，形成聚合物微细流变成形尺度效应的新分析方法；建立考虑尺度效应的聚合物微细结构热辊压成形模型，揭示工艺参数对成形精度和性能均匀性的影响规律及调控机制，形成介观尺度下薄膜微细结构热辊压成形成性一体化新工艺；提出薄膜微细结构热辊压成形新机构及多辊协调控制方法，构建聚合物薄膜微细结构热辊压成形原理样机，建立聚合物薄膜微细结构加工新实验方法，从材料、工艺和装备三方面为聚合物薄膜微细结构控形控性加工做出重要探索。

薄膜表面微细结构可显著提升薄膜太阳能电池、柔性显示器等薄膜器件的光线利用率或出光效率，对产品性能具有重要影响。这类微结构加工是典型的介观尺度制造范畴，不仅需要控制微结构的形状，而且需要控制其内部物理性能。本项目将热模压工艺与卷对卷运动复合，提出聚合物薄膜微细结构直接热辊压连续成形成性新方法。主要研究进展如下：.(1) 聚合物薄膜微弯曲实验发现弯曲模量随薄膜厚度降低非线性增加的尺度效应现象，揭示了旋转应变梯度增大导致材料强化的尺度效应机理；基于Eying粘性模型与Langevin超弹性模型，将旋转梯度引入变形功和广义应变，建立考虑尺度效应的聚合物弹粘塑性本构模型，预测精度较传统模型提高15%。.(2) 基于考虑尺度效应的本构模型，引入Williams-Landel-Ferry方程描述温度对材料性能的影响，建立成形工艺仿真分析模型；研究辊压包络充型和脱模过程中聚合物材料的流变行为，获得了瞬时弹性和蠕变应变分布规律，建立了工艺参数与脱模回弹特征映射关系，实现了聚合物微细结构成形高度精确预测。.(3) 构建聚合物表面微细结构卷对卷直接热辊压成形系统，开展成形工艺实验，发现了单个微结构坍塌和大面积微结构高度阶跃的缺陷新现象，通过仿真分析揭示界面黏附功与弹性变形能共同作用的缺陷形成机理；提出了梯度冷却-连续保压新机构，有效控制微结构回弹，扩大了成形工艺窗口，辊压速度提高了5倍。.(4) 研究聚合物薄膜材料改性新方法，将MMA与BA共聚合成P(MMA-co-BA)，提高了材料流动性；基于非极性的Si-O-Si键，引入VTPMS共聚合成P(MMA-co-BA-co-VTPMS)，提高了脱模性；原位聚合共聚合成了石墨烯/P(MMA-co-BA) ，提高了薄膜的折光指数，开发了新型光学级聚合物薄膜。.在IJP、IOP-JMM、IEEE-Nanotechnology、科学通报等国内外期刊上发表论文50篇，其中SCI检索44篇，SCIE他引177次；1篇论文入选ESI高被引，1篇封面论文；国际会议论文9篇；申请发明专利15项，授权6项。研究成果获麻省理工学院Hardt教授(ASME Fellow)等知名学者引用，支撑了康得新复合材料集团的高性能光学薄膜开发。