【作者】 刘辉；

【导师】 叶红齐；

【作者基本信息】 中南大学 ， 化学工艺， 2007， 博士

【摘要】 为了提高无机粉体的分散及耐腐蚀等应用性能，本文在对两种丙烯酸酯聚合过程（甲基丙烯酸甲酯MMA乳液聚合与三羟甲基丙烷三丙烯酸酯TMPTA溶液聚合）动力学研究的基础上，进行了丙烯酸酯在氧化铝（Al₂O₃）、片状铝粉（FAl）以及纳米铝粉（Al）表面的原位聚合，从而制备核壳结构的聚丙烯酸酯／氧化铝或金属铝复合粒子。为了尽可能使聚合反应在颗粒表面发生，分别使用了添加偶联剂与表面引发的方法，系统研究了复合粒子制备过程中单体转化率（C）、接枝率（PG）与接枝效率（GE）的影响因素，并对所制备的复合粒子进行了性能评价，最后考察了聚丙烯酸酯／片状铝粉复合粒子在涂料工业中的应用。1、MMA乳液聚合与TMPTA溶液聚合的动力学研究。对于过硫酸铵（APS）引发的MMA乳液聚合，随着聚合温度、APS浓度、MMA浓度、十二烷基硫酸钠（SDS）浓度的升高，转化率均呈增大的趋势。而对于偶氮二异丁腈（AIBN）引发的TMPTA的溶液聚合，实验聚合速率R_p∝C_AIBN^0.211、R_p∝C_TMPTA^2.807与理论结果R_p=KC_AIBN^0.25C_TMPTA³基本相符。其中，MMA的转化率略高于TMPTA，而PMMA的分子量却低于PTMPTA。2、原位乳液聚合制备PMMA／Al₂O₃复合粒子及其表征。在原位乳液聚合制备PMMA／Al₂O₃复合粒子的过程中，采用阴离子型乳化剂SDS效果较佳，且只有当其浓度远高于临界胶束浓度时，才能获得高PG的复合粒子。对于偶联剂，异丙基三（十二烷基苯磺酰基）钛酸酯（NDZ）比甲基丙烯酰氧基丙基三甲氧基硅烷（MPS）更有利于提高复合粒子制备过程中的C、PG与GE，且其实验最佳用量与NDZ在Al₂O₃表面单分子层作用的理论值相吻合。TEM与XPS均表明通过原位乳液聚合己成功制备出以Al₂O₃为“核”、PMMA为“壳”的PMMA／Al₂O₃复合粒子，并建立了复合粒子壳层厚度δ与接枝率PG之间的定量关系：δ=ρ（Al₂O₃）·D·PG/6·ρ（PMMA）。3、原位乳液聚合制备PMMA／FAl复合粒子及其表征。采用阳离子型乳化剂十六烷基三甲基溴化铵（CTAB）有利于获得分散性能更佳的复合粒子，且随着其浓度的增大，体系乳液类型由反相微乳液转变为正相微乳液。在此基础上，运用表面引发原位聚合制备了PMMA/FAl复合粒子，其过程分为两步：带正电的片状铝粉吸附阴离子型引发剂APS，然后在其表面进行MMA的原位乳液聚合，研究发现，APS在片状铝粉表面的吸附属于典型的物理吸附，且吸附率PA与C_APS的关系可用Freundlich模型等温吸附式PA=8．912C_APS^1.0749来描述；在较优条件下表面引发原位聚合过程中PG可达20．5％，且实验所得表观接枝聚合反应速率R_g=KC_FAl^0.521·C_APS^0.429·C_MMA^0.978与理论方程R_g=KC_FAl^1/2·C_APS^1/2·C_MMA吻合较好，并得出接枝聚合反应表观活化能为65．1kJ·mol^-1。另外还在未吸附引发剂的情况下，考察了MPS对PMMA／FAl复合粒子制备过程的影响，结果表明，经MPS偶联后，PG由9．5％增至17．2％，但仍低于表面引发原位聚合过程中的PG。4、原位溶液聚合制备PTMPTA／FAl复合粒子及其表征。TMPTA在FAl表面的原位溶液聚合初期反应速度较快，且随着TMPTA浓度的增加，接枝聚合速率、均聚速率与总聚合速率均线性增大。当MPS偶联率为3．1％时，PTMPTA／FAl复合粒子制备过程中PG与GE分别可达4．3％与33．5％，但低于PMMA／FAl制备过程的PG与GE，这是由于TMPTA的长碳链以及三个碳碳双键导致其在铝粉表面原位聚合需克服更大的空间位阻所致。与片状铝粉相比，PTMPTA／FAl表面的铝含量从30．1％降至4．2％、碳含量从40．5％增至62．4％、氧含量从29．4％增至33．4％，这是PTMPTA接枝于片状铝粉表面的结果。5、原位溶液聚合制备PTMPTA／Al纳米复合粒子及其表征。由于纳米铝粉的高比表面，制备PTMPTA／Al纳米复合粒子所需单体用量多于PTMPTA／FAl。同时，功能性单体丙烯酸的存在有利于C、PG与GE的提高，且其较优用量与单纯TMPTA溶液聚合所需用量一致。与纳米铝粉相比，PTMPTA／Al复合粒子的活性得到了良好的保持：60天后纳米铝粉的活性下降约为50％，而PTMPTA／Al的活性基本保持不变。6、聚丙烯酸酯／片状铝粉复合粒子在涂料工业中的应用。与原料片状铝粉相比，聚丙烯酸酯／片状铝粉复合粒子，特别是PTMPTA／FAl的耐腐蚀性能与附着性能得到显著的提高，因此在铝银浆涂料行业中，采用多官能团的长链丙烯酸酯类单体对其进行聚合改性将具有广泛的应用前景。更多还原

【Abstract】 In order to improve application performances of inorganic powders, such as dispersibility and corrosion resistance, polyacrylate/（alumina or aluminum） composite particles with core-shell structure were prepared by in situ polymerization of acrylate on the surface of alumina （Al₂O₃）, flaky aluminum （FA1）, and nano-aluminum （Al）. Based on the kinetics of emulsion polymerization of methyl methacrylate （MMA） and solution polymerization of trimethylolpropane triacrylate （TMPTA）, several methods, such as coupling agent and surface-initiated polymerization, had been used to enhance polymerization to occur on the surface of particles. And the conversion （C）, percentage of grafting （PG）, and grafting efficiency （GE） in the preparation were systematically studied. In addition, the properties of resulting composite particles were evaluated, and the polyacrylate/FAl composite particles were applied in the painting industry.1. Kinetics of MMA emulsion polymerization and TMPTA solution polymerization. With regard to MMA emulsion polymerization initiated by ammonium persulfate （APS）, monomer conversion increased with the increasing polymerizing temperature, APS concentration, MMA concentration, and sodium dodecylsulfate （SDS） concentration. As far as TMPTA solution polymerization initiated by azobisisobutyronitrile （AIBN） was concerned, the experimental polymerization rate ( Rp∝C_AIBN^0.211 and Rp∝C_TMPTA^2.807 ) was basically consistent with thetheoretical result (R_p =KC_AIBN0.25)C _TMPTA³). The conversion of MMA was alittle higher than TMPTA, while the molecular weight of PMMA was lower than PTMPTA.2. Preparation and characterization of PMMA/Al₂O₃ composite particle by in situ emulsion polymerization. Anionic emulsifier, SDS, played an important role in the preparation of PMMA/Al₂O₃ composite particle, and only when SDS concentration was far higher than its critical micelle concentration, could PMMA/Al₂O₃ with high PG be obtained. Concerning the coupling agent, titanium tris（dodecylbenzene-sulfonate） isopropane （NDZ） was more advantageous than 3-methacryloxypropyl-trimethoxysilane （MPS） to the increases of C, PG, and GE, and its optimum experimental dosage accorded with theoretical value of single-molecular-layer adsorption between NDZ and Al₂O₃. TEM and XPS showed that PMMA/Al₂O₃ composite particle had a core-shell structure, and the quantitative relationship between thickness ofpolymeric shell layer and PG was established asδ=ρ（Al₂O₃）·D·PG/ 6·ρ（PMMA）.3. Preparation and characterization of PMMA/FAl composite particle by in situ emulsion polymerization. Cationic emulsifier, cetyl trimethyl ammonium bromide （CTAB）, was favorable to preparation of PMMA/FAl composite particle with good dispersibility, and the microemulsion system changed from reverse to positive with the increasing CTAB. The preparation of PMMA/FAl composite particle by surface-initiated in situ emulsion polymerization was divided into two steps: adsorption of anionic APS on the surface of positively charged FA1, following by in situ polymerization of MMA. It was found that the adsorption of APS onto FA1 was typical physical process, and the relationship between percentage of adsorption （PA） and C_APS could be described with the Freundlich modeling PA = 8.912C_APS^1.0749 . At the optimum conditions PG could attain 20.5% in the surface-initiated in situ emulsion polymerization. The experimental apparent grafting polymerization rate R_g = KC_FAl^0.521·C_APS^0.429·C_MMA^0.978 was consistent with thetheoretical equation R_g = KC_FAl^1/2·C_APS^1/2·C_MMA, and the apparent activationenergy of grafting polymerization was calculated as 65.1kJ·mol^-1. In addition, PMMA/FAl composite particle was also prepared in the presence of MPS. It was shown that PG was still lower than that in the case of surface-initiated in situ polymerization, although PG increased from 9.5% to 17.2% in the presence of MPS.4. Preparation and characterization of PTMPTA/FAl composite particle by in situ solution polymerization. The polymerization rate was quick at the beginning, and the grafting, homogeneous and total polymerization rates linearly increased with the increasing TMPTA concentration. In the preparation of PTMPTA/FAl, PG and GE could attain 4.3% and 33.5%, respectively, when the percentage of coupling （PC） of MPS was 3.1%. The fact that PG and GE in this case were lower than that of PMMA/FAl may be explained with strong steric hindrance of TMPTA with long carbonic chain and three C=C bonds. Compared to raw FA1, the content of Al, C, and O for PTMPTA/FA1 changed from 30.1%, 40.5%, and 29.4% to 4.2%, 62.4%, and 33.4%, respectively, indicating that PTMPTA had been grafted on the surface of FAl.5. Preparation and characterization of PTMPTA/Al nanocomposite particle by in situ solution polymerization. Due to huge specific surface area of nano-aluminum, the required monomer amount of PTMPTA/Al was more than that of PTMPTA/FAl. The existence of functional monomer （acrylic acid） was useful to the improvement of C, PG, and GE in the preparation of PTMPTA/Al, and the optimum amount was consistent with solution polymerization of pure TMPTA. Compared with that of raw nano-aluminum, activity of PTMPTA/Al nanocomposite particle had been well preserved: activity of nano-aluminum after 60 days decreased about 50%, while activity of PTMPTA/Al kept changeless.6. The application of polyacrylate/FAl composite particle in the painting industry. Compared to that of raw FAl, corrosion resistance and adhesive force of polyacrylate/FAl composite particles, especially of PTMPTA/FAl, had been markedly improved. It was concluded that the modification with multi-functional long-chain acrylate monomer would have extensive application prospect in the aluminum paste painting industry.更多还原