【作者】 江四九；

【导师】 李效玉；

【作者基本信息】 北京化工大学 ， 材料学， 2010， 博士

【摘要】 氟硅丙共聚物具有优异耐候性、热稳定性和化学稳定性,尤其是其超低表面能特性,使其具有疏水疏油、耐沾污、自清洁等功能,在涂料、织物整理、皮革涂饰等领域有着广泛的应用。氟硅丙共聚物的合成研究具有非常重要的意义和应用价值。乳液聚合是合成氟硅丙共聚物的重要方法之一,以水作为分散介质,聚合速度快,安全环保。本论文使用不同的乳液聚合工艺,包括常规乳液聚合和细乳液聚合方法,合成了高性能的含氟丙烯酸酯、有机硅和丙烯酸酯的共聚物乳液,在分析研究共聚物乳液的结构、性能及其应用的基础上,进一步对细乳液聚合反应动力学及其成核机理进行了深入研究。主要工作包括：含氟丙烯酸酯核壳乳液的设计合成及具有高疏水性涂层的制备。高效发挥含氟单体在共聚物中的作用一直是合成氟硅丙共聚物的难题。本论文以甲基丙烯酸十二氟庚酯(DFMA)为含氟共聚单体,以乙烯基三(p-甲氧基乙氧基)硅烷(A-172)为交联功能单体,通过对粒子的结构和形态的设计,使用种子半连续乳液聚合法合成了含氟丙烯酸酯核壳乳液,合成的氟硅丙共聚物乳液具有内软外硬的核壳结构,含氟聚合物在粒子最外层。使用红外分析仪(FTIR)、透射电镜(TEM)、差示扫描量热仪(DSC),接触角、X射线光电子能谱(XPS)、原子力扫描电镜(AFM)等对共聚物乳液的性能和结构进行了表征。结果表明该乳液可以在使用极少量的含氟单体情况下,极大提高共聚物涂层的表面疏水性。使用合成的乳液制备了不同疏水性的涂层,对比分析了涂层的耐沾污性,研究表明涂层的疏水性的增加,可以显著提高涂层的耐沾污性。2.采用两步细乳液聚合法合成具有良好织物整理性能的含氟丙烯酸酯接枝改性有机硅乳液。含氟有机硅乳液是多功能的织物整理剂,既可赋予织物良好的柔软性和手感,又能使织物能够防水防油。但合成含氟有机硅乳液的环硅氧烷单体和含氟单体水溶性小,常规乳液聚合速度慢,乳液聚合不稳定,聚合物乳液常会出现漂油现象,影响织物整理效果。本论文采用两步细乳液聚合法合成了含氟丙烯酸酯接枝改性有机硅乳液：先通过八甲基环四硅氧烷(D4)／四甲基四乙烯基环四硅氧烷(D4V)的阳离子细乳液聚合成含乙烯基的有机硅聚合物,再通过自由基细乳液聚合使含氟丙烯酸酯接枝到有机硅链上,系统研究了D4v含量与含氟单体用量对乳胶粒子结构和性能影响,得到了既具有良好的柔软整理效果、又具有很好的防水整理效果的含氟有机硅乳液。通过D4／D4v的常规乳液聚合和细乳液聚合的对比,发现细乳液聚合法合成有机硅乳液,聚合速度快,乳化剂用量少,得到的乳液稳定性好。3.D4单体细乳液的制备方法和稳定性研究。单体细乳液的制备和单体细乳液稳定性是进行细乳液聚合的关键。本论文以D4作为模型单体,应用静态多重光散射(MLS)和动态激光光散射(DLS)技术对单体细乳液的制备方法进行了研究。从单体细乳液液滴稳定性角度,深入分析高速分散机、超声波仪和高压均质机三种分散设备对D4单体的细乳化作用。由于三种设备在细乳化过程中作用原理不同,所制备的单体细乳液稳定性也不相同,采用高压均质制备的单体细乳液粒径及粒径分布都较小,稳定性最好。进一步对高压均质制备单体细乳液过程中,影响单体细乳液粒径及粒径分布的工艺条件和乳液配方等因素进行了研究,并对单体细乳液的液滴大小及其分布、乳化剂含量和温度等因素对高压均质法制备的单体细乳液稳定性的影响进行了讨论。4.D4的阳离子细乳液聚合动力学研究D4的阳离子细乳液聚合具有其独特的动力学及热力学特征。本论文系统研究了单体细乳液粒径和引发／乳化剂十二烷基苯磺酸(DBSA)的用量对聚合反应速率的影响,确认了D4的阳离子开环聚合的主要场所应该在油／水的界面上,并提出DBSA对D4的开环聚合存在着体积效应和位阻效应。在此基础上本论文建立油／水界面的三层分子模型,根据界面模型和聚合机理推导了D4阳离子开环聚合速率方程,使用试验数据确定了聚合速率方程中的参数值。聚合速率方程表明聚合速率与单体起始浓度([D4]0)、单体细乳液的粒径(r)和DBSA分子在粒子表面的覆盖率(x)存在相关性。使用不同粒径、不同DBSA浓度、不同单体浓度的单体细乳液进行聚合,验证了聚合速率方程在本实验体系中的正确性。5.D4的阳离子细乳液聚合成核机理研究.应用动态激光光散射对D4的阳离子细乳液聚合过程的粒径变化进行跟踪,发现随聚合反应的进行,细乳液粒径不断减小。单体D4的密度与聚合物PDMS的密度接近,因此粒径的减小并不是聚合反应过程密度的变化所致,这意味着在D4细乳液聚合过程中除了单体液滴成核外还存在其他成核方式。鉴于低分子量的端羟基PDMS具有D4单体具有较大的亲水性,本论文提出在单体液滴成核的基础上,还存在部分均相成核：D4开环聚合生成的低分子量端羟基PDMS进入水相成核,并推导了乳液粒径与单体转化率间的关系式。该关系式表明转化率的自然对数和细乳液粒径的自然对数之间存在着线性关系,并通过不同条件下的细乳液聚合试验数据进行了验证。在此基础上,进一步分析了单体细乳液的粒径、乳化剂用量、温度对体系中均相成核过程的影响。更多还原

【Abstract】 Fluorine-silicon-acrylate copolymers are one kind of materials with high performance including excellent weather resistance, thermal and chemical stability, and particularly the ultra-low surface free energy, which make the surface water-repellent, oil-repellent and self-cleaning. Fluorine-silicon-acrylate copolymers are widely used as coating, textile finishing, leather finishing and so on. The study on the preparation of fluorine-silicon-acrylate copolymers is remarkable and worthwhile. As an important method for the preparation of high performance fluorine-silicon-acrylate copolymers, emulsion polymerization has many advantages, such as the high polymerization rate, safety and no pollution. In present dissertation, high performance emulsions of polymers copolymerized by fluorinated-acrylate, silicone and acrylate were synthesized by different emulsion polymerization techniques including the seeded emulsion polymerization and the miniemulsion polymerization, and the structures, properties and the application behaviors of the emulsions were studied. Furthermore, the kinetics and the nucleation mechanism of the cationic ring-opening miniemulsion polymerization of D4 were systemically explored. The main research works are as follows:1. The synthesis of fluorine-containing latex with core-shell structure and the preparation of coatings with high hydrophobic surfaces.A pivotal question in the synthesis of fluorine-silicon-acrylate copolymers is how to minimize the amount of fluorinate monomers. In this paper, the latex particles were designed with core-shell structures and synthesized by semi-continuous seeded emulsion polymerization. The latex core is composed with low Tg poly(methyl methylacrylate-butyl acrylate) (P(MMA-BA)). The latex shell is composed with high Tg P(MMA-BA) containing vinyl tris(β-methoxyethoxy) silane (A-172) and dodecafluroheptyl methacrylate(DFMA). A-172 is serving as the crosslinking monomer. DFMA is the functional monomer which provides the anti-water properties. The core-shell latex has been characterized by various methods, such as fourier-transform infrared spectrometry (FTIR), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), the X-ray photoelectron spectroscopy (XPS), a video-based contact angle measuring device and atomic force microscope (AFM). The result shows that the surface hydrophobic property characterized by the values of advancing contact angle and receding contact angle for water, were dramatically improved with low amount of DFMA. Coatings prepared by the synthetic latex with different DFMA and A-172 content were compared and the antifouling capability of the coatings were analyzed. It was found that the anti-fouling capability was improved with the increase of hydrophobic property.2. The synthesis of polysiloxane latex grafted by F-containing acrylate via a two-step miniemulsion polymerization method.The fluorine-containing polysiloxane latex is used as multifunctional textile finishing, which provides the textile with pleasant softness and water-repelling properties. However, the low solubility of cyclosiloxanes and fluorinated monomer in water make them unstable in conventional emulsion polymerization. In this dissertation, a fluorine-containing polysiloxane latex were synthesized via two-step miniemulsion polymerization:vinyl groups were introduced into the polysiloxane by ring-opening copolymerization of octamethylcyclotetrasiloxane (D4) and tetravinyltetramethylcyclotetrasiloxane (D4V) in miniemulsion, then the fluorinated monomer(DFMA) were grafted onto polysiloxane by radical copolymerization. The effect of the content of D4V and DFMA on the structure and properties of the emulsion was investigated. The fluorine-containing polysiloxane latex, prepared with appropriate content of D4V and DFMA, is of high performance on the softening and water-repelling properties when it is utilized as a finishing of textile. A comparative study on the conventional emulsion polymerization and miniemulsion polymerization of the polymerization was also carried out. The result shows that the miniemulsion copolymerization of D4/D4V has many advantages, such as the higher polymerization rate, lower emulsifier concentration and better stability. 3. The study on mini-emulsification method and the stability of the correspondingly miniemulsions.The preparation of monomer miniemulsion is the key step in the miniemulsion polymerization. In this dissertation, D4 was chosen as the model monomer and the effects of preparation methods were systemically studied by static multiple light scattering (MLS) and dynamic laser scattering (DLS) technique. Monomer miniemulsion of D4 were prepared by three different devices, rotor-stator system, sonifier and high-pressure homogenizer, respectively and the the stability of monomer miniemulsions were estimated. The results show that the monomer miniemulsion prepared by high-pressure homogenizer was most stable. Furthermore, the effect of homogenization condition and the recipes on the droplet size and distribution (DSD) of monomer miniemulsion were studied in detail. The influences of the droplet size of monomer miniemulsion, the concentration of DBSA and the temperature on the stability of monomer miniemulsion were also discussed.4. Kinetic study on the cationic polymerization of D4 in miniemulsion.The cationic polymerization of D4 in miniemulsion is of its unique kinetic and thermodynamic feasures. A kinetic study on the ring-opening polymerization (ROP) of D4 in miniemulsion is presented in this dissertation. The polymerization was initiated by dodecylbenzenesulfonic acid (DBSA) which also served as the surfactant (inisurf). The influence of the size of monomer droplet and the concentration of DBSA on the polymerization rate were studied. With the main place for the ROP of D4 confirmed at the oil/water interface, a three-layer interface model was proposed to analyze the distribution of molecules in the interface and the effects of the DBSA. A kinetic equation was then developed based on the interface model. In the equation, the polymerization rate (Rp) was related to the initial monomer concentration ([D4]0), the droplet radius (r), the coverage of DBSA on monomer droplets surface (χ). The polymerization rate can be predicted from the kinetic equation after all the parameters determined. Finally, the equation was verified by the good accordance of the predicted polymerization rate data with the experimental results under different polymerization conditions.5. The study on the nucleation mechanism in the cationic polymerization of D4 in miniemulsion.The miniemulsion polymerization of octamethylcyclotetrasiloxane (D4) was carried out and the particle sizes during polymerization were monitored by DLS technique. Although the monomer miniemulsion was homogenized very well by a high-pressure homogenizer, the particle sizes kept on decreasing with the increase of the monomer conversion in the polymerization, which indicated the occurrence of new particles. Considering the hydrophilicity of the components in the miniemulsion system, a homogenous nucleation of oligomers was likely to happen besides the primary droplet nucleation mechanism. The oligomers nucleation mechanism was justified by the linear relationship between the natural logarithm of the particles diameter (lnd(t)) and the natural logarithm of conversion of monomer(lnf(t)). In addition, the influence of the inisurf concentration and the polymerization temperature on the ratio of the oligomers entering water phase to all the polymers produced were discussed.更多还原