【作者】 刘展鹏；

【导师】 林原斌；

【作者基本信息】 湘潭大学 ， 高分子化学与物理， 2005， 博士

【摘要】 电流变流体是一种新颖的智能材料,具有重要的学术研究价值和广泛的应用前景,是功能材料最活跃的研究领域之一。本论文对电流变效应的特点、历史起源及其理论模型和应用进行了文献综述。从分子设计的原理出发,合成了两类电流变流体分散相材料及两种分散介质材料。考察了各材料的合成及电流变效应; 探讨了这些材料组成的电流变流体体系中,材料的相关性能与其电流变效应的关系。考察了2-甲氧基-5-辛氧基-1,4-双氯甲基苯及4,4’-双氯甲基-1,1’-联苯这两个聚合物前体中所涉及的芳烃的氯甲基化反应; 同时,对4,4’-双甲酰基-1,1’-联苯及4,4’-二氰甲基-1,1’-联苯的合成条件进行了优化。采用Gilch 方法,经4,4’-双氯甲基-1,1’-联苯的自缩合反应,合成了PBPV; 采用Wittig反应,以2-甲氧基-5-辛氧基-1,4-双氯甲基苯及4,4’-双甲酰基-1,1’-联苯等为原料,“一锅”法合成了PMOBPV; 采用Knoevenagel 反应,以4,4’-双甲酰基-1,1’-联苯及4,4’-二氰甲基-1,1’-联苯等为原料合成了CNPBPV。对三种联苯撑乙烯类聚合物的合成过程进行了优化,聚合物的分子结构、热性质、粒子形貌及介电性质等均得到了测试表征。分别以对苯二胺、间苯二胺和2,5-二氧环己二甲酸二甲酯等为原料,经缩合、氧化、环化等反应,合成了平面梯形聚合物聚喹吖-[2,3-b]-啶-7,14[5,12] -二酮(PTQA)及聚喹吖-[2,3-b]-啶-12,14[5,7]-二酮(PCQA)。对两种喹吖啶酮聚合物的合成过程进行了探讨,优化了合成条件; 聚合物的分子结构、热性质、粒子形貌及介电性质等均得到了测试表征。分别以氯代甲苯和溴苯、氯苄等为原料,经溴化反应及F-C 反应合成了两种电流变流体的分散介质材料溴化氯代甲苯(BCT)和对溴二苯甲烷(BDPM)。两种有机液体的分子结构及相关物化性质均得到了测试表征。系统研究了PBPV、PMOBPV及CNPBPV三种联苯撑乙烯类聚合物分散在硅油中形成的电流变流体的稳定性及流变性质。结果表明,由于三种共轭聚合物具有适当的电导率和介电常数,因此显示出较好的电流变效应。粒子浓度为30wt%的PBPV,PMOBPV及CNPBPV三种聚合物的硅油体系室温下的屈服应力分别达802.3 Pa ( 2kV/mm ) 、1301.4 Pa (3kV/mm) 及1827Pa(3kV/mm); 电流密度分别为100μA/cm~2(2kV/mm)、28.7μA/cm~2(3kV/mm)及34μA/cm~2(3kV/mm); 体系的屈服应力随电场强度增强而增大,符合:τ_y ∝E~ n ,指数n分别为1.88,1.9,及1.58; 各聚合物悬浮体更多还原

【Abstract】 Electrorheological fluid (ERF) is a novel type of smart materials, which is of remarkable academic interest and extensive potential application. It has become one of the most active research fields in functional materials. In this dissertation, the nature of the ERF and its theoretical model as well as its development and application has been extensively reviewed. Two types of novel conjugated polymers and two dispersing-medium materials were designed and synthesized according to the molecular design principles. The ER properties of these novel smart materials have been intensively studied. The relationship between the ER effect of these novel materials and their related properties was discussed. In the synthesis of the conjugated polymers precursors, 2-methoxyl-5-octyloxy-1,4-dichloromethylbenzene and 4,4’-bischloromethyl-1,1’-biphenyl, the reaction conditions of chloromethylation reaction were thoroughly investigated. Meanwhile, 4,4’-diformyl-1,1’-biphenyl and 4,4’-dicyanomethyl-1,1’-biphenyl were synthesized and the reaction conditions were optimized. The conjugated polymer, polybiphenylenevinylene (PBPV) was synthesized based on the self-condensation reaction of 4,4’-bischloromethyl-1,1’–biphenyl via Gilch method; Poly(2-methoxyl-5-octyloxylphenylene-1,4-vinylene-biphenylene-4,4’-vinylene) (PMOBPV) was synthesized based on the “one-pot method ”of 2-methoxyl-5-octyloxy-1,4-dichloromethylbenzene with 4,4’-diformyl-1,1’-biphenyl via Wittig reaction; Polybiphenylene-4,4’-vinylene-1-cyano (CNPBPV) was synthesized based on the Knoevenagel reaction of 4,4’-diformyl-1,1’-biphenyl with 4,4’-dicyanomethyl-1,1’-biphenyl. All polymer synthetic conditions were optimized; the molecular structure, thermal properties, morphology and dielectric properties of these resulting polymeric particles were characterized. Plane ladder-like polymers, polyquin (2,3-b) acridine-7,14 (5,12) dione (PTQA) or polyquin (2,3-b) acridine-12,14 (5,7) dione (PCQA) was synthesized based on the condensation reaction of 1,4-phenylenediamine or 1,3-phenylenediamine with dimethyl 2,5-dioxocyclohexane-1,4-dicarboxylate, subsequently cyclization and dehydrogenation. The reaction conditions were thoroughly investigated. The molecular structure, thermal properties, morphology and dielectric properties of the resulting polymers were characterized. Bromochlorotoluene (BCT) was synthesized based on the bromonization reaction of chlorotoluene with Br2; Bromodiphenylmethane (BDPM) was synthesized based on the Friedel-Crafts reaction of bromobenzene with chlorobenzyl. The molecular structure and physical properties related to the ER effect were characterized. The stability and rheological properties of the PBPV, PMOBPV or CNPBPV suspensions in silicon oil were intensively investigated. The results show that, due to proper conductivity and dielectric properties of the dispersed materials, these polymeric suspensions can be polarized to form fabricated chains under electric field, which leads to good ER activity with low current density: The yield stress reaches up to 802.3 Pa (2kV/mm), 1354.2 Pa (3kV/mm) and 1919.2Pa (3kV/mm) under the current density of only 100 μA/cm2 (2kV/mm), 28.7 μA/cm2 (3kV/mm)and 34 μA/cm2(3kV/mm) respectively for 30 wt.% polymer-based ER fluids at room temperature; the yield stress of these suspensions increases with the electric field strength, and shows the relationship as τy ∝E n, where n equals to 1.88,1.9,1.58 respectively for PBPV, PMOBPV and CNPBPV-based systems; The yield stress linearly increases with the particle concentration, and has a maximum as increasing the employed temperature. The apparent viscosity of the ER fluids increases with the electric field strength, while decreases with the shear rate, i.e., shear-thinning effect. The results also show that the difference in molecule structure of the dispersed materials leads to the difference in ER activity. The conductivity of the dispersed materials has only effect on the current density of the ER Fluid. Moreover, it is the difference in dielectric constant of the dispersed-phase materials that contributes to the difference in yield stress of the ER fluids. The rheological properties of the suspensions of PTQA and PCQA in BDPM were also studied. The results show that, these systems exhibit excellent ER activity under electric field. Under 3kV/mm electric field, the yield stress of 30 wt% PTQA and PCQA suspensions reaches up to 6.0 and 4.0 kPa under the current density of only 21.7 and 14.3 μA/cm2 respectively at room temperature. The yield stress linearly increases with squared electric field strength and the particle concentration, has a maximum as increasing the employed temperature.The apparent viscosity of the ER fluids increases with the electric field strength, while decreases with the shear rate, i.e., shear-thinning effect. The excellent ER activity and the difference in these two systems are attributed to the novel molecular structure as well as the difference in the molecular regularity. The influence of the dispersing phase on the stability and rheological properties of PTQA-base suspension was investigated. The results show that, the sedimentation rate of the ERF depends on the density difference between the dispersing particles and the medium, as well as the viscosity of the medium. The yield stress of the ERF is proportional to the dielectric constant of the medium which is in well agreement with the dielectric loss model.更多还原