【作者】 王筠；

【导师】 白如科；

【作者基本信息】 中国科学技术大学 ， 高分子化学与物理， 2010， 博士

【摘要】 两亲性聚合物由于同时含有化学性质不同的链段,易发生微相分离,因此它们在选择性溶剂、表面、本体等结构中表现出自组装特性,广泛用于表面活性剂、纳米材料、药物载体、涂料、胶粘剂、分离膜、热塑弹性体等。当含氟链段作为疏水基元引入两亲性聚合物时,由于其特有的低表面能、疏水疏油性、低折射率、低介电常数、良好的耐候性等,赋予材料独特而优异的性能。众所周知,聚合物的性能由其结构决定,因此,不同链段的组成、相对含量、在聚合物分子内的分布以及聚合物的拓扑结构等因素,直接影响两亲性聚合物的自组装行为,从而改变其在选择性溶剂、表面和本体中的聚集形态,表现出各自独特的物理化学性质。本论文的研究内容包括,单体的结构设计与合成、两亲性聚合物的合成、聚合物结构与性能关系的研究及应用。1.设计、合成了两种Y形含氟两亲性单体,即丙烯酸1-(1H,1H,2H,2H-全氟癸氧基)-3-(3,6,9-三氧杂癸氧基)-异丙醇酯(FA)和N-(1H,1H,2H,2H-全氟癸基)-N-(3,6,9-三氧杂癸基)丙烯酰胺(FAM),并研究了两种单体的本体RAFT均聚反应。实验结果表明,两者的聚合反应都具有活性自由基聚合特征,分子量随单体转化率线性增加,PFA的分子量分布小于1.4。两种单体都能溶于水,具有表面活性剂的性质,FA的临界胶束浓度(CMC)为0.15 mmol／L,其水溶液能达到的最低表面张力为20.0 mN／m,FAM的表面活性比FA更高,其CMC为0.038 mmol／L,水溶液能达到的最低表面张力为18.6 mN／m。均聚物PFA和PFAM都具有良好的热稳定性。PFA和PFAM在室温下都为粘稠液体,在玻璃基片上无法形成聚合物薄膜。PFA能溶于通常的有机溶剂,并具有一定的表面活性；PFAM几乎不溶于通常的有机溶剂。由此可见,由于亲水基团、疏水基团与可聚合双键的Y形连接点结构不同,单体及均聚物的性能差异显著。作为对照研究,合成了与FAM结构类似的非氟单体,N-(十二烷基)-N-(3,6,9-三氧杂癸基)丙烯酰胺(CAM)。其均聚物PCAM在通常的非极性溶剂中溶解性良好,在强极性溶剂中溶解性较差,这充分表明碳氟链与碳氢链对聚合物的性能有显著影响。2.合成了一系列FA及FAM与甲基丙烯酸-2-(二甲胺基)乙酯(DMAEMA)的嵌段及无规共聚物,系统考察了两亲性单体结构、含量及在聚合物分子内的分布(无规与嵌段共聚物)对两亲性共聚物溶液及表面性能的影响。通过表面张力测试研究了聚合物在水溶液中的表面活性。实验数据显示,含氟无规共聚物能有效地降低水的表面张力(γ＜25 mN／m),其临界聚集浓度(CAC)随氟单体含量增加而减小。FAM共聚物的CAC比FA共聚物的CAC更小,当浓度大于CAC时,其水溶液的表面张力更低,表现出更高的表面活性。与无规共聚物相比,嵌段共聚物降低水表面张力的能力较差。此外,通过1H NMR和19FNMR研究了共聚物结构(无规／嵌段)对全氟碳链在水溶液中缔合行为的影响。无规共聚物中的全氟碳链在水中缔合形成相对疏松的氟碳疏水区,而嵌段共聚物中的全氟碳链在水中缔合形成相对密实的氟碳疏水区。通过静态接触角测试对共聚物的表面性能进行研究,所有共聚物对水的接触角都显示出时间依赖性,对油(正十六烷)的接触角随时间几乎不变,表现出环境响应性。随着氟单体含量的增加,共聚物膜的亲水性下降,疏油性增加。嵌段共聚物具有比无规共聚物更好的亲水疏油性。FAM嵌段共聚物对水和油的的接触角都比FA嵌段共聚物小,而其无规共聚物对水和油的接触角都比FA无规共聚物大。当FA嵌段共聚物中FA含量为9.1%时,对水的接触角值在30秒内由48.19°下降到27.81°,对油的接触角为70.40°,表现出优异的亲水疏油性。基于这一特性,我们进一步考察了FA系列共聚物的防雾和抗油性能。实验结果表明,上述FA含量为9.1%的嵌段共聚物具有良好的防雾性和抗油性。最后,合成了含有甲基丙烯酸-2-(羟基)乙酯的三元共聚物,并通过交联剂将其固化在经过修饰的玻璃表面,形成稳定的聚合物涂层,对其进行防雾和自清洁测试。结果显示,与无规共聚物相比,嵌段共聚物具有良好的防雾和自清洁性能。3.设计、合成了Y形非氟两亲性单体,N-十二烷基-N-(3,6,9-三氧杂癸基)-4-乙烯基苄胺(SCT),分别与N-乙烯基咔唑(VK)及N-(4-乙烯基苄基)咔唑(StK)进行共聚,制备了一系列嵌段与无规共聚物。初步研究了聚合物对多壁碳纳米管(MCNT)在不同溶剂中的分散作用,考察了咔唑单体结构、PSCT链段长度及共聚物结构对聚合物分散MCNT性能的影响。结果显示,共聚物在其良溶剂(DMF和甲苯)中对MCNT的分散效果较好,并且两亲性单体含量的增加有助于提高聚合物对MCNT的分散性能。4.以α-溴代己内酯为引发剂,通过ATRP反应合成了结构精确的带有ε-己内酯端基聚苯乙烯,除去端基溴原子后,通过亲核试剂与己内酯的开环反应,制备了一系列单端异双官能团聚苯乙烯。以其中端基为二甲胺和羟基的聚苯乙烯为前体,通过羟基与丙烯酰氯的缩合反应,将丙烯酸酯基引入聚苯乙烯链末端,再通过二甲胺基与苯磺酸的离子相互作用,将PEG接入聚苯乙烯末端,成功地制备出V形离子键两亲性大分子单体。更多还原

【Abstract】 It is well known that amphiphilic polymers can self-assembly to form a variety of morphologies in selective solvents, on the surfaces of substrates, and in bulk because of phase separation between hydrophilic and lipophilic segments. The unique properties of the amphiphilic polymers lead to many applications in different fields, such as surfactants, nanomaterials, drug carriers, coating materials, adhesives, separation membranes, thermoplastic elastomers. When a fluorinated segment as a hydrophobic part is incorporated into amphiphilic polymers, it can provide some unique properties due to its low surface energy, hydrophobicity, lipophobicity, low refractive index, low dielectric constant, and weathering resistance. Since the properties of polymer depend on its structure, there is no doubt that the morphology of assemblies formed by amphiphilic polymers is related to the length, distribution, and chemistries of each chain segments as well as the polymer architectures. The main content of this dissertation includes design and synthesis of amphiphilic monomers and polymers, investigation on the relationship of structure and properties of polymers and their applications.1. Two kinds of Y-shaped amphiphilic fluorinated monomers,1-(1H,1H,2H, 2H-perfluorodecyloxy)-3-(3,6,9-trioxadecyloxy)-propan-2-yl acrylate (FA) and N-(1H,1H,2H,2H-perfluorodecyl)-N-(3,6,9-trioxadecyl) acrylamide (FAM), have been designed and synthesized. The RAFT homopolymerization of each monomer in bulk has been investigated, and the results showed that both polymerization bear characters of controlled radical polymerization. The molecular weight increases with increasing conversion of monomer, and the molecular weight distributions of PFA is below 1.4. Both of FA and FAM are soluble in water and exhibit excellent surface activity. The critical micelle concentration (CMC) of FA is 0.15 mmol/L and the lowest surface tension of its aqueous solutions is 20.0 mN/m. FAM shows better surface activity than FA as evidenced by smaller CMC and lower surface tension of the aqueous solutions as 0.038 mmol/L and 18.6 6m//m, respectively. The homopolymers of FA and FAM exhibit good thermostability. Both PFA and PFAM are viscous liquid at room temperature, and it is hardly to obtain high quality thin films on glass substrates. PFA is soluble in common organic solvents and shows surface activity. PFAM is hardly soluble in common organic solvents. These results indicate that the chemical structure of the Y-shaped linking part, which links the hydrophilic group, hydrophobic group, and polymerizable group together, has significant influence on the properties of homopolymers. In order to compare with the fluorinated polymer, a nonfluorinated analogue of FAM, N-dodecyl-N-(3,6, 9-trioxadecyl) acrylamide (CAM), has been synthesized. The homopolymer PCAM shows high solubility in apolar solvents and low solubility in strong polar solvents. This result indicates that the properties are quite different between amphiphilic polymers containing fluorocarbon moieties and hydrocarbon moieties.2. A series of block and random copolymers of FA or FAM with 2-(N, N-dimethyl-amino)ethyl methylacrylate (DMAEMA) have been synthesized and the influence of the copolymer structure on their solution and surface properties has been investigated, including the chemical structure, content and distribution of the amphiphilic fluori-nated monomer in copolymers. The surface activity of copolymers in water was examined by surface tension measurements of their aqueous solutions. The results indicate that the fluorine-containing random copolymers can decrease the surface tension of water effectively (y<25 mN/m), and the critical aggregation concentration (CAC) of copolymers decreases with increasing the content of fluorinated monomer. The copolymers containing FAM have lower CAC and surface tension of aqueous solution than the copolymers containing FA, which means the surface activity of the former is better than the latter. In comparison with random copolymers, the block copolymers are less effective for decreasing the surface tension of water. In addition, the aggregation behaviors of the copolymers have been investigated by 1H and 19F NMR. The results show that the fluorocarbon segments in the hydrophobic domain formed by random copolymers have more mobility than that in the hydrophobic domain formed by block copolymers. The surface properties of the copolymer thin films were examined by static contact measurements using water and oil (hexadecane). All the water contact angles of the copolymers show time-dependent behavior, but the oil contact angles do not change over time. This means the surfaces exhibit environ-ment-dependent sitimuli-responsibility. With increasing the content of fluorinated monomers, the hydrophilicity of copolymer thin film surfaces decreases while the oleophobilicity of the surfaces increases. The block copolymers show better hydro-philic and oleophobic properties than the random copolymers. The water and oil contact angles of the block copolymers containing FAM are higher than those con-taining FA, but the values of the random copolymers containing FAM are lower than those containing FA. When the content of FA in block copolymers exceeds 9.1%, the film surface show excellent hydrophilicity and oleophobicity as evidenced by the water contact angle decreases from 48.19°to 27.81°in 30 seconds and the oil contact angle is 70.40°. Based on this result, we examined the anti-fog and oil-repellent pro-perties of the copolymer thin films containing FA. The experiment results show that the block copolymers with 9.1% of FA exhibits simultaneously good anti-fog and oil-repellent properties. Finally, tercopolymers containg FA, DMAEMA, and 2-hydroxy-ethyl methylacrylate (HEMA) have been synthesized and used to construct durable anti-fog and oil-repellent coatings on the glass surfaces by crosslinking reaction. However it was found that the random copolymers don’t possess simultaneously anti-fog and self-cleaning properties.3. A novel Y-shaped non-fluorinated amphiphilic monomer, N-dodecyl-N-(3,6,9-trioxadecyl)-4-vinyl-benzylamine (SCT), has been synthesized and copolymerized respectively with N-vinylcarbazole and N-(4-vinylbenzyl)carbazole by RAFT poly-merization. We investigated dispersion of the multi-walled carbon nanotube (MCNT) with the block and random copolymers in different solvents, including DMF, THF, chloroform, toluene, n-hexane and water. The experiment results indicate that the MCNT can be dispersed by the polymer when a solvent is good for the polymer, and the increasing of the SCT content can improve the dispersion efficiency.4. Well-definedε-caprolactone end-capped polystyrenes have been synthesized by ATRP of styrene usingα-bromo-ε-caprolactone as initiator. After removing the end bromine atoms, the ring-opening reactions of s-caprolactone end groups with nucleo-philes yield monoend-biheterofunctional polystyrenes. Then polystyrene containing dimethylamine and hydroxyl groups at one chain end was used as precursor for constructing V-shaped macromonomer. In order to introduce polymerizable groups into the end of polystyrene, acryloyl chloride was reacted with hydroxyl end group. V-shaped ion-bonded amphiphilic macromonomer has been prepared via ionic interaction between sulfonic acid groups in the sulfonic acid end-capped PEG and dimethylamine groups in the a-dimethylamine-a-acrylate polystyrene.更多还原