【作者】 胡园园；

【导师】 张超灿；

【作者基本信息】 武汉理工大学 ， 材料物理与化学， 2010， 博士

【摘要】 从功能梯度材料概念出发,将含氟丙烯酸酯聚合物与其它价格便宜粘结性好的聚合物共混,通过巧妙的梯度复合技术,使膜材料的一侧表面具备有机氟的优点,另一侧表面具备其它聚合的优异性能,而在膜的厚度方向上组分连续过渡,无任何不良宏观界面,这样可以解决含氟丙烯酸酯表面性能优越但粘结性差价格昂贵所造成的使用限制。最引人注目的梯度材料的制备方法是自组织法,而目前用自组织法制备梯度材料的研究主要集中在可能会造成环境污染的溶液体系和耗能高的熔融体系,环保节能的乳液体系中,由于聚合物被乳化剂包裹,不同聚合物乳胶粒性能差别很小,缺乏梯度形成的驱动力,而少有人研究。本论文概述了高分子梯度材料的研究进展及自组织形成梯度结构的理论依据和影响因素,在分析乳液共混体系自组织形成梯度结构条件的基础上,设计制备了含氟丙烯酸酯与普通丙烯酸酯共混梯度乳胶膜,讨论了成膜温度、热处理温度和时间、聚合物的玻璃化转变温度,共混比例,乳胶粒的粒径,成膜的基材、含氟烷基侧链以及共聚物的加入对含氟丙烯酸酯聚合物共混乳液自组织形成梯度结构的作用。首先,研究了成膜温度、热处理温度和时间、玻璃化转变温度对含氟丙烯酸酯共混乳液自组织梯度成膜的影响。选择Tg不同但含氟量和表面能相近的六种含氟丙烯酸酯聚合物分别以1/1与丙烯酸酯共聚物共混,得到六种共混乳液。将共混乳液在不同温度下(15℃,30℃,45℃,60℃)成膜,后在110℃/170℃下进行了热处理。用接触角法测试了乳胶膜的表面能；单点反射红外光谱测试了膜正反两面的基团信息；SEM-EDX分析了乳胶断面的元素分布；AFM测试了膜的表面形貌和分相情况,XPS测试了膜的表面元素。结果表明：控制成膜温度高于共混两组份的最低成膜温度是直接成膜不热处理得到氟浓度梯度的必要条件,满足此条件的情况下,使含氟组分的Tg高于不含氟组分,加大两组份的Tg差并降低成膜温度有利于得到梯度结构。含氟乳胶粒在共混体系干燥的时候未进行融合和扩散有利于在组分Tf以下Tg以上热处理形成氟浓度梯度结构。热处理温度升高到组分的黏流温度以上使体系中两组分发生明显相分离,不利于梯度结构的形成。对于含氟丙烯酸酯Tg高于普通丙烯酸酯的共混体系,研究了两种乳液的乳胶粒粒径及含量对膜表面性能及梯度结构的影响,用AFM表征了膜的表面形貌,ATR-FTIR、XPS、SEM-EDX表征了膜的表面及内部组成,表面能测试和膜的附着力测试表征了膜的表面性能,结果发现含氟丙烯酸酯粒径远小于普通丙烯酸酯的粒径有利于含氟乳胶粒在膜F-A面富集并在膜断面方向呈浓度梯度分布,成膜之后热处理(高于含氟组分Tg的温度)使膜具备明显沿膜厚方向的氟浓度梯度,且共混体系中含氟乳液含量达到30%即可以得到氟浓度梯度结构膜,膜的F-A面具备纯丙烯酸酯的优异表面性能。对于含氟丙烯酸酯／普通丙烯酸酯的共混体系(含氟组分Tg高),选用了不同表面能的铝、不锈钢、玻璃、聚四氟乙烯四种基材成膜并进行热处理,研究了不同成膜基材对乳胶膜梯度结构的影响。用接触角法测试了共混乳液在不同基材上成的膜及膜经过110℃、210℃退火不同时间的表面能,用SEM-EDX测试乳胶膜断面的元素分布和含量,同时也测试了热处理前后不同基材上乳胶膜的附着力。结果表明,增大基材的表面能,减小膜厚,有利于热处理之后氟组分浓度梯度的形成。在表面能很高的金属基材上,控制膜厚小于20μm,高于组分黏流温度热处理后,可以得到膜F-A面为100%含氟组分,膜F-G面为95%以上的普通丙烯酸酯组分,中间组分浓度连续变化,无不良界面的完美梯度结构。在表面能较低的玻璃基材上,膜厚要小于10μm才能得到完美梯度结构,PTFE基材上的膜只能形成夹心结构。研究了共聚物的加入对含氟／无氟丙烯酸酯乳液共混体系相容性、膜表面性能和梯度结构的影响。通过表面能、’附着力、DSC和膜的断面SEM-EDX表征发现：含氟／无氟丙烯酸酯共聚物加入到含氟／无氟丙烯酸酯共混体系中后,有利于体系相容性的改善,但对膜的表面性能及梯度结构影响不大。将与普通丙烯酸酯共混的含氟组分改为含氟丙烯酸酯与不含氟丙烯酸酯的共聚物后,体系中含氟单体单元含量减小到18%,室温成膜即可形成氟浓度梯度,在组分Tf以下Tg以上热处理以及共聚物中含氟烷基侧链的加长有利于梯度结构的完美及表面性能的提高。更多还原

【Abstract】 Based on the concept of gradient polymer blend films and self-stratification mechanisms, a gradient blend film with surface property of fluorinated polyacrylate on one side and good adhesion on another side is possible by blending fluorinated polyacrylate latices and other latices. If achieved, the incompatibility of the fluorinated film with substrate could be avoided. The self-organization process over a heterophase liquid applied a driving force during the film-forming process so as to distribute the phases between the air and substrate is simple and tractable. However, the self-stratification mechanism was mainly applied in solution system which usually uses poisonous organic solvents and melts systems which usually need high temperature and is energy consuming. With regard to the latex blends system which is environmentally friendly and energy saving, the polymers are covered by emulsifier such that the surface free energies of different latex particles in the system are of little differences. Unfortunately, the differences of surface free energies between different latex particles have been a main provider of the driving force during the self-organization process in the blends system. So the formation of gradient structures by self-organization in latex blends system is difficult due to the lack of driving forces. In this paper, the self-organization process of gradient structure in latex blends system were discussed in detail, the effect factors on gradient, such as temperature, Tg, particle size, substrates and so on were studied.The effects of film-formation temperature (FFT), heat treatment and Tg on the self-organized film-formation of fluorinated/non-fluorinated polyacrylate latex blends were studied. To this end, six kinds of fluorinated polyacrylate latices with different Tg and same content of fluorine were prepared and mixed with the same non-fluorinated polyacrylate latex, respectively. All the blends latices were dried at 15℃; 30℃; 45℃and 60℃. The surface properties and morphologies were characterized by contact angle measurement and AFM. The element composition and structure of films across the section was analyzed by XPS, SEM-EDX and ATR-FTIR. The results showed that, drying at temperatures above the MFFT of fluorinated component is necessary for the enrichment of fluorinated component on film-air interface (F-A) of the film and formation of gradient structure. Moreover, when the Tg of fluorinated component is higher than that of the non-fluorinated polyacrylate, the big difference of Tg of the two components and the low FFT are in favor of the formation of gradient structures of the films. Compared with that of sample whose two components can film-formation at room temperature, the two components of sample which only one component can film-formation at room temperature were easier to self-organize to the different surface of the film during film-formation and anneal process because of their different Tg. Increasing the heat treatment temperature above the Tf of polymers make for the phase separation but the formation of gradient structure.The effects of particle size of the components and content of PF6MBA on the gradient structure of films were discussed. The content of fluorine in film-thickness direction was analyzed by XPS depth profiling, SEM-EDX and ATR-FTIR. The surface properties and morphology were characterized by contact angle measurement and AFM. It was found that, after film-formation at room temperature and anneal 2h at 110℃, the fluorine content increased from F-G to F-A gradually in the blends film whose fluorinated polyacrylate latex with smaller particle size and higher Tg than that of fluorine-free polyacrylate latex. Moreover, the content of PF6MBA in the system was above 30%is necessary for the gradient structure and the pure fluorinated polyacrylate surface of F-A.The effects of substrates of film on the gradient structure were discussed. The blend latex was film-formed on Al, Steel, Glass, and PTFE. The content of fluorine in film-thickness direction was analyzed by XPS depth profiling, SEM-EDX and ATR-FTIR. The surface properties and morphology were characterized by contact angle measurement and AFM. The result shows that increasing the surface free energy of substrate and decreasing the thickness of film would promote the formation of perfect gradient structure(the fluorinated polymer content increased from 0%on F-G to 100%on F-A gradually) after anneal above the Tf of polymer.The effects of adding the fluorinated acrylate copolymer in fluorinated/non-fluorinated polyacrylate latex blend on the surface property, gradient structure and compatibility of the blend film were studied by surface free energy testing, adhesion test, DSC and SEM-EDX. The results showed that the compatibility of the blend system was improved after adding the copolymers. The increasing of the fluorine content of copolymer was beneficial to the formation of gradient structure. The copolymer had little influence on the surface property of the films. Blending fluorinated polyacrylate copolymer and non-fluorinated polyacrylate copolymer latexes, the gradient structure film was abtained while film-formation at room temperature, the gradient structure was obviouse after annealing at 110℃, the lengthening of the fluorinated chain segment was in favour of the gradient structure and surface property.更多还原