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1、应用全息散射确定光致聚合物光化学反应参数摘要 当下是信息技术飞速发展的年代，如今人们的生活已经发展成及接受和存储信息的大数据时代。在对这些巨大信息存储时，我们需要一个更为优良的存储技术来代替普通的存储技术。所以导致光学体的全息技术迅速成为存储技术的焦点，光学题全息技术就是一种新型的存储技术，它对于数据的存储具有密度高，寿命长且容易携带等优点。光学体全息技术对于数据的输入和读出是采用非接触的方式，这与普通的存储技术相比大大提高了信息的传输速率。在信息数据存储方面，传统的存储技术是将信息数据中所有数据的每一个小的数据点都占有一定的存储空间，在数据存储密度较大时，由于存储介质存在缺陷尺寸，将会引起数
2、据的丢失。光学体全息存储是将信息以图片的形式存在也就是说将所有信息作为一个整体的形式存储在介质中，在数据密度增大时，只会引起数据的存储信息强弱的变化，不会导致数据的丢失，这对数据的存储安全更加有利。光学体全息技术存储数据的材料有很多种，例如：银盐材料、重铬酸盐明胶（DCG)、光折变晶体、光致聚合物等。 而我们只采用光致聚合物这材料进行研究。 本实验采用的是光致聚合物作为光学体全息技术的材料，光致聚合物是一种混合型材料，它本身包括：单体、热引发剂和粘结剂。但再聚合过程中会导致材料的体积发生改变，需要调整入射光的角度才能形成最大的衍射光栅。本次试验从众多光致聚合物材料中选取一种最适合试验的材料是掺
3、杂菲醌的聚甲基丙烯酸甲酯（PQ-PMMA）作为实验样品。此材料具有可忽略的收缩和能够制备成毫米量级厚度的特性，是一种非常有潜力的大容量高且密度全息存储介质。令人遗憾的是PQ-PMMA材料还不是很理想，材料的缺点为较高的全息散射和较低的响应速率，这大大影响了材料在应用方面的前景。但是人们很少的去研究光化学动力学方面来改善材料本身的缺点。本文章是建立起模型后在对测量出的参数进行分析，建立的模型光化学反应的扩散模型。采用该模型的主要原因为光致聚合物具有非局域的效应，且更适合材料的动力学参数的测算。从而去研究光化学内部的动力学过程。其光化学反应的动力学参数：量子产率和摩尔吸收系数是光化学反应进行状态主
4、要物理量。 光致聚合物在相干光照射下，PQ-PMMA光致聚合物内部的PQ分子吸收光子形成自由基，再与PMMA基底发生光链接反应，最终引起折射率调制度的增加。这种光化学反应与典型的链式聚合反应有很大的差别，正是这一特殊的光化学反应过程使得我们能够应用全息散射方法确定光化学反应的参数。全息散射的方法论证了它在确定一些具有高透明度和强全息散射的物质，例如确定PQ-PMMA的动力参数。首先我们定义了一个聚合速率参数，这个参数是由散射损失的暂时演化所确定的。两个基本的动力参数为量子产率和摩尔吸光效率，通过非线性拟合聚合速率参数作为厚度函数的曲线而得到这两个动力参数。采用波长为532nm的激光光经过空间滤
5、波器和准直透镜变成一束准直的平行光。然后在去照射不同角度的PQ-PMMA材料。用探测器探测到入射光强度和透射光强度。然后在用公式进行计算出两个参数分别为计算出量子产率和摩尔吸收系数这两个动力学参数的平均值分别为2.7mol/einstein和/mol。利用透射率测量法再次对这两个动力学参数的合理性进行验证。关键词： 量子产率 摩尔吸收系数 光致聚合物ABSTRACTToday, men have entered the information era where all kinds of information are intertwined in our life. To store the
6、se massive information, we need to substitute advanced storage technology for conventional storage technology, thus making optical holographic technology become the focus of storage technology. Optical holographic technology as a new type of storage technology is characterized by high density, long
7、lifetime and easiness to carry in terms of data storage. Optical holographic technology inputs and reads data in anon-contact manner, greatly increasing the transmission rate of information as compared to ordinary storage technologies. When it comes to information storage, each information data occu
8、pies a space in traditional storage technologies. In the case of an increase in storage density, data loss will ensue due to the defect size existing in storage medium. Optical holographic storage stores information in medium in the form of hologram. When data density increases, only the strength of
9、 data storage will be affected and data loss will not be caused, which is more conducive to data storage.The materials used by optical holographic technology include silver salt materials, dichromated gelatin (DCG), photorefractive crystal and photopolymer.Photopolymer, a hybrid material consisting
10、of monomer, thermal initiator and binder, is what adopted as the material for optical holographic technology in this experiment. However, since the volume of materials will be changed during polymerization, the angle of incident light needs to be adjusted to form the largest diffraction grating.Phen
11、anthrenequinone-mixed polymethyl methacrylate(PQ-PMMA) is a photopolymer material with negligible shrinkage and the characteristic of preparing millimeter-level thickness, acting as a holographic storage medium featuring great potential, high capacity and high density. But there still exist such sho
12、rtcomings as higher holographic scattering and a low response rate in PQ-PMMA material, exerting a great influence on the prospect of its application. But the important parameters can be analyzed and calculated by using holographic scattering to study the photochemical reaction within polymers. Usin
13、g holographic scattering, this paper calculates the quantum yield and molar absorption coefficient of the photopolymer PQ-PMMA.Under coherent light exposure, the PQ molecules within the photopolymer PQ-PMMA absorb photons to form free radicals, produce optical link reaction with PMMA substrate and f
14、inally cause an increase in the modulation degree of refractive index. There exists a substantial difference between this photochemical reaction and typical chain-reaction polymerization. It is this special photochemical reaction that enables us to use the method of holographic scattering to determi
15、ne the parameters of photochemical reaction.A laser with a wavelength of 532 nm was transformed into a beam of collimating parallel light through a spatial filter and a collimating lens to irradiate the PQ-PMMA material of different angles. Incident light intensity and transmission light intensity w
16、ere detected with a detector. And then, the formula was applied to calculate two parameters, namely, quantum yield and molar absorption coefficient, whose mean values were, 2.7mol/einstein and 1.3X /mol, respectively. Then, the method of transmissivity measurement was used to validate the rationality of these two kinetic parameters.“Key Words”: Quantum yield Molar absorption coefficient Photopolymer目 录第一章 绪论11.1 课题背景及研
