【作者】 赵瑞阳；

【导师】 马於光；

【作者基本信息】 吉林大学 ， 高分子化学与物理， 2014， 博士

【摘要】 1937年S. Hartley发现光照射偶氮苯可以获得一种黄色的物质，偶氮苯分子特殊的顺反异构现象逐渐被人们所认知、了解，偶氮苯类材料显示出优异的光致顺反异构可逆性，在众多光响应材料中受到更广泛的关注。偶氮苯类化合物在光刺激下，能够可逆地发生顺反异构，可以导致材料在物性，例如颜色、尺寸、形状、极性、折射率和溶解性等方面的变化。研究发现反式构象和顺式构象在相互转换过程中会有0.9nm的尺寸变化，这种大的尺寸变化使偶氮苯类材料薄膜在受到光刺激下会发生局部分子运动，导致宏观的质量迁移。基于这种质量迁移理论，1995年P. Rochon和D. Y. Kim两个小组提出了偶氮苯类材料应用于表面浮雕光栅方面的可能性，近二十年来相关研究备受关注。虽然利用偶氮苯类材料实现光响应图案化的制备研究取得不断进步，但是获得实际应用还需克服很多问题。首先是机理的问题，质量迁移理论普遍适用于偶氮苯类光响应材料，但是具体的迁移过程以及迁移方式，人们还是没有一个肯定得答案，此类材料光响应图案化的机理仍然没有被认清；其次，图案稳定性还存在很大问题，偶氮苯类材料形成的表面图案化，其热稳定性取决于材料本身的玻璃态转变温度，目前采用的材料（例如侧链型偶氮苯聚合物）的玻璃态转变温度普遍不高，而且图案化后微结构的耐酸、碱、有机溶剂的能力也有待提高。本论文针对偶氮苯类材料在光响应方面存在的问题，根据实验观察提出了表面浮雕光栅形成的机理模型，尝试采用电化学沉积的方法制备交联结构薄膜解决稳定性问题，重点开展以下三方面研究：1.发展偶氮苯类材料在表面浮雕光栅上的应用并探索其形成机理。我们设计并合成了共轭主链中含有偶氮苯基团的聚合物，以共轭聚合物制备光响应图案化为重点，并对其形成的表面浮雕光栅进行仔细分析，建立偶氮苯类分子质量迁移模型，提出确切的质量迁移机理，为后续此类工作的展开提供依据。2.探索偶氮苯类材料形成稳定的表面浮雕光栅的方法。我们设计并合成一种以光响应基团为中心，以高电化学活性的咔唑基团为侧链端基的有机小分子，通过电化学沉积的方法获得具有光响应性质、表面平整、高度交联的电聚合薄膜。由于这种薄膜的交联度非常高，其激光加工形成光栅的稳定性比一般旋涂薄膜高很多。此种在电化学沉积薄膜上激光加工微结构的方法有望被应用于纳米压印技术上，简化其模板制作过程，丰富模板的多样性，同时为纳米结构在光电器件上的应用提供可能。3.探索偶氮苯类材料在分子捕捉方面的可行性，我们设计并合成八官能度的含偶氮苯基团的电化学沉积前体，并且通过电沉积方法制备了表面平整、交联度高的三维孔结构的电聚合薄膜，并且这种全刚性的薄膜仍具有光辐照顺反异构的性质，通过顺反异构改变薄膜中孔直径的大小，起到开关作用以捕捉有机小分子，从而实现了分子牢笼的设想。更多还原

【Abstract】 In1937, S. Hartley first found that the collar of azobenzene could change fromorange red to yellow when azobenzen was irradiated by one special light. Since then,the different conformations of azobenzene, the cis-configuration and trans-configuration are gradually understood and cognized. The excellent isomerization ofthe two configuration of azobenzene is a subject of widespread concern. Till nowsome soft materials with photo-response moiety are chosen to construct artificialmuscles because they possess such necessary properties as good mechanicalflexibility, high corrosion resistance, and high molecular orders. Up to now, severaltypes of photo-response polymers have been developed as organic actuator materials,including polymer gel, movement of free-standing solid films, photo-inducedexpansion, shape memory polymers, and liquid-crystal polymer (LCPs). In the lastfive decades, regarded as well-known photo-response actuators, azobenzene and itsderivatives have been extensively investigated due to their photo-induced geometricisomerization. This kind of compounds possesses some special properties in theprocess of reversible photo-isomerization between cis-configuration and trans-configuration, reflected in their size, shape, polarity, refractive index, conductivity,solubility and so on. The isomerization of cis-trans configuration can induce masstransfer which can be roughly classified into three levels as illustrate. At themolecular level light generates trans-cis-trans isomerization which depletes thechromophore concentration in the direction of polarization, at the domain level thepolar chromophore movement reorients polar domains and at the mass level the light produces macroscopic movement of polymer the can be used to inscribe surface orbulk patterns. Based the mass transfer theory, photo-response molecules andpolymers with azobenzene moiety was first introduced to the field of micro-/nano-fabrication in1995by Rochon and Natansohn. Lots of literatures were reportedabout photo-induced surface patterning using azo-polymer.Although many related work in the preparation of photo-induced surfacepatterning using materials with azobenzene moiety were reported, some problemsstill exist as follows to be solved. The first problem is the issue of the formationmechanism of the photo-induced SRG. Generally, mass transfer theory is applicableto the azobenzene photoresponsive material, but the precise migration process andmigration patterns still don‘t have a certain answer to explain by now. It means thatthe exact mechanism of photo-induced SRG with azo-polymers is still notrecognized, which seriously hinders its deeper research and application in industry.The second problem is the issue of stability of photo-induced SRG. The thermalstability of the photo-induced surface patterning using azo-polymer is totallydepended by the glass transition temperature (Tg) of the material itself. And at thesame time, the Tg of most of azo-polymer are widely concerned not high enough, sothe stability of the photo-induced patterning is not good enough. Besides the thermalstability, general acid, alkali, and organic solvent can also destroy pattern indeed,which seriously affects the application foreground of photoresponsive materials withazobenzene moiety.Based on the current problems about photoresponsive materials with azobenzenemoiety, herein, our thesis research is focus on the following three aspects:1. Develop a kind of novel azobenzene materials used in photo-induced pattern andexplore its mechanism. We design and synthesize a conjugated polymer withazobenzene moiety in the main chain, named PFAzo. Then, the SRG pattern isformed on the surface of the PFAzo film by interfering laser beam irradiated.From the knowledge obtained, the mechanism of the photo-induced patternformation in the present system is first assumed by us as follows. After beingirradiated by interfering laser beam, the CP chains transform from a rigid-rodstructure of trans-configuration to a random coil of cis-configuration. This conformational change induces a large local stress which drives the polymerchain to transfer from light irradiation part to dark part. Based on this process,thus the highly contrast surface pattern is formed.2. Explore a novel method to obtain stable photo-induced pattern by azobenzenematerial. We design and synthesize an electrochemical deposition (ED) precursornamed as DFCzAzo, which contains both electroactive carbazole groups andphoto-controlled azobenzene moiety. The polymerization reaction occurs amongthe radical cations with deposition of the cross-linked polymer film onto theelectrode. The highly cross-linked network results to the excellent stability of thephoto-induced nano-structures. We believe that the present photo-controlledsystem will provide a novel concept for creation of steadily cross-linked ED filmand will play an important role in many potential applications, such as the designof novel optical devices, and micro-/nano-scale sculpture.3. Investigate the feasibility of conjugated microporous polymers (CMPs)containing azobenzene moiety in terms of molecule capture. We design andsynthesize a novel ED precursor named as DTCzAzo, which contains both eightfunctionality electroactive carbazole groups and photo-responsive azobenzenemoiety. A highly cross-linked three-dimensional pore structure of the polymericfilm is produced by the electrochemical deposition method. And the film still hasa rigid isomerization property just as the polymer spinning coated film. Thediameter of pore structure changes in the process of the trans-to-cisisomerization, to capture organic molecules with the suitable molecules size.Then we achieve the target of fabricating a molecular cage.更多还原