【作者】 罗振寰；

【导师】 詹晓力；

【作者基本信息】 浙江大学 ， 化学工程与技术， 2010， 博士

【摘要】 低表面能涂层聚合物因其独特的性能,如疏水性、不粘性以及耐候性等,在航空航天、印刷、建筑、服装以及防污防腐等方面得到了广泛的应用。聚硅氧烷改性聚氨酯,通过在共聚物中引入赋予低表面能性质的聚硅氧烷软段,同时聚氨酯结构单元赋予优良的力学性能以及表面附着力,已成为低表面能涂层聚合物领域最为活跃的研究领域之一。聚合物结构与性能是高分子领域永恒的话题。聚硅氧烷聚氨酯共聚物根据聚硅氧烷链段在聚合链上所处的位置,可分为主链嵌段型以及侧链接枝型两类。链段化学结构、链段组成及其在主链的链接形式是影响共聚物低表面性能、表面微相分离结构、表面化学组成的关键因素。本文围绕主链嵌段结构、侧链接枝结构的聚硅氧烷改性聚氨酯,对聚合物涂层低表面性能、表面微相分离结构以及表面化学组成进行了研究,旨在阐述三者之间的关系,以期对聚硅氧烷改性聚氨酯低表面能涂层聚合物的分子设计提供依据。本文首先分别通过硅氧烷环体的阴离子/阳离子开环聚合得到单Si-H/双Si-H封端的聚硅氧烷,再经硅氢加成合成了不同形式的羟烷基封端聚硅氧烷。并以此聚硅氧烷,聚己内酯（PCL）为混合软段,异佛尔酮二异氰酸酯（IPDI）为硬段,氨丙基三乙氧基硅烷为扩链剂,采用两步溶液聚合合成了不同组成,不同链接方式的聚硅氧烷改性聚氨酯共聚物。利用静态接触角,动态接触角研究了共聚物膜的疏水性能;采用轻敲模式下的原子力显微镜（AFM）研究了共聚物膜的表面微相分离行为;并采用X光电子能谱（XPS）分析了共聚物膜表面的元素组成,考察了链段化学结构、链段组成及其在主链的链接形式的影响,探讨了低表面性能、表面微相分离结构,以及表面化学组成之间的相互关系。具体研究内容及主要结论如下:1.羟烷基封端聚硅氧烷的合成与表征1、利用酸白土催化D₄阳离子开环聚合,有效控制分子量分布,合成了平均分子量可控、分子量分布窄的双Si-H封端的PDMS。2、利用丁基锂引发D₃/F₃的阴离子开环聚合,采取低温,高单体浓度以及较低转化率手段控制开环聚合存在的“反咬”及“再分布”副反应,合成了平均分子量可控、分子量分布窄的单Si-H封端的聚硅氧烷。3、合成得到分子量分布在1.2-1.4之间,聚硅氧烷重复单元数约为15,35,50的双Si-H封端PDMS、单Si-H封端PDMS以及单Si-H封端PMTFPS。4、提出使用六甲基二硅氮烷作为羟基保护剂代替传统的三甲基氯硅烷的羟基保护方法,有效避免了硅氢基团与羟基之间的副反应,简化了反应工艺。硅氢加成合成得到了双端羟烷基的PDMS,单端双羟烷基的PDMS以及单端双羟烷基PMTFPS。2.主链嵌段结构聚二甲基硅氧烷改性聚氨酯的表面性能1、PDMS可有效地降低PDMS主链嵌段结构改性聚氨酯共聚物膜的表面能。共聚物膜表面的水接触角随PDMS含量的增加而增大,渐趋于一最大值,约为110°。PDMS链段越长,上述现象更为显著。退火温度的升高,水接触角随之增大,有利于聚硅氧烷链段的表面富集。2、前进接触角及后退接触角随PDMS含量的增加而增大,接触角滞后随PDMS链段增加而变小,表面的亲水基团减少,有利于形成持久低表面能。3、所有的共聚物膜表面都能观察到5-20nm尺度的微相分离结构。随PDMS链段长度、PDMS含量的增加,其微相分离程度明显增强,微相结构有“双连续相”向“海岛”结构转变。高退火温度有利于聚硅氧烷链段向表面富集,微相分离程度增强,相区的尺寸增大。4、硅元素在涂层表面出现明显富集,硅氧烷链段伸向空气界面,随深度的变化硅元素逐渐下降,当信息深度为10nm左右时的元素组成仍然大于本体组成,PDMS链段增长,PDMS含量增加以及退火温度升高均有利于硅元素的表面富集。3.侧链接枝结构聚二甲基硅氧烷/聚三氟丙基里基硅氧烷改性聚氨酯的表面性能1、PDMS（PMTFPS）可有效地降低聚硅氧烷侧链结构改性聚氨酯共聚物膜的表面能。共聚物膜表面的水接触角随聚硅氧烷含量的增加而增大,渐趋于一最大值,约为110°。本实验的聚硅氧烷组成范围内,水接触角与聚硅氧烷链长关系不大。退火温度的升高,水接触角随之增大,有利于聚硅氧烷链段的表面富集。2、前进接触角及后退接触角随聚硅氧烷含量的增加而增大,接触角滞后随聚硅氧烷链段增加而变小,表面的亲水基团减少,有利于形成持久低表面能。3、在本文考察范围内,侧链接枝结构共聚物膜表面均不能形成清晰的纳米尺寸微相分离,表面为均一的聚硅氧烷富集层。4、硅元素在涂层表面出现明显富集,硅氧烷链段伸向空气界面,随深度的变化硅元素逐渐下降,当信息深度为10nm左右时的元素组成仍然大于本体组成,聚硅氧烷链段增长,聚硅氧烷含量增加以及退火温度升高均有利于硅元素的表面富集。5、在实验聚硅氧烷含量范围内,含氟基团CF₃CH₂CH₂-引入对降低表面能无显著影响。4.聚硅氧烷的链接形式对聚硅氧烷改性聚氨酯低表面性能的影响1、主链嵌段和侧链接枝两种链接方式硅氧烷改性聚氨酯均能有效降低涂层表面能,随PDMS含量增加表面聚硅氧烷链段的富集趋于恒定,水接触角达到稳定的最大值,约为110°。侧链接枝结构较主链嵌段结构其静态接触角较大,而同时接触角滞后更明显,表现出表面能更低,但同时难以保持持久低表面能。2、在相同组成下,主链嵌段结构较侧链接枝结构有清晰的表面微相分离结构,表面Si元素组成相对较小,疏水基团的表面富集作用相对较弱。3、侧链接枝结构较主链嵌段结构共聚物表现出表面能更低,但同时难以保持持久低表面能的性质可能与其聚硅氧烷链段自由度高,链段运动能力强,同时易于表面富集及表面重构有关。更多还原

【Abstract】 Low surface energy coating polymer because of its unique properties, such as hydrophobicity, non-sticky, and weather resistance, etc., has been widely used in the aviation and aerospace, printing, construction, clothing, and anti-pollution anti-corrosion, etc. With polydimethylsiloxane (PDMS) as soft segment polyurethane (PU) block copolymers by the introduction of low surface energy siloxane structural units, giving a copolymer of low surface energy properties, while polyurethane structural unit also gives excellent mechanical properties of copolymer and surface adhesion. In recent years, polydimethylsiloxane (PDMS) as the soft segment of polyurethane block copolymers has become one of the most active research areas.The relationship between structure and properties of polymer is eternal topic of this area. According to the existing form of PDMS, PDMS-PU copolymer can be divided into two types: segmented and grafted copolymers. The chemical structure, composition and linkage form are the key factors impacting the low surface energy of copolymers. This thesis concerned on the segmented/grafted copolymers, low surface energy, microphase separation and surface chemical composition have been studied to elaborate the relationship of the above three, with a view of providing the basis for molecular design of the polysiloxane modified polyurethane coating low surface energy polymer.With the use of self-polysiloxane soft segment, poly caprolactone (PCL) as mixed soft segments, isophorone diisocyanate (IPDI) as hard segment, aminopropyl triethoxysilane as a chain extender, using two-step solution polymerization, a series of different composition, different ways linked PDMS-PU copolymer. The use of static contact angle, dynamic contact angle study of hydrophobic properties of the copolymer film; using tapping mode atomic force microscope (AFM) study of the copolymer film on the surface to investigate the separation behavior; and using X-ray photoelectron spectroscopy (XPS) analysis of the copolymer membrane surface elements. Explore the surface morphology of phase separation, surface hydrophobic properties, as well as block the relationship between chain structures. 1. synthesis and characterization of different forms of hydroxyl-terminated alkyl polysiloxaneA. With the use of acid treated bentonite as the catalyst, a series of functional polysiloxane hompolymers with relatively narrow molecular weight distribution were successfully prepared.B. A series of mono-functional polysiloxanes with different molecular weight were synthesized. Reaction route for the anionic ring-opening polymerization of D3/F3 was designed and correspondent reactors for the polymerization were constructed.C. Di-Si-H terminal PDMS, mono-Si-H terminal PDMS and mono-Si-H PMTFPS were successfully synthesized, the molecular weight distribution were between 1.2 and 1.4, the repeat unit number were 15,35 and 50, respectively.D. For the use of hexamethyldisilazane as a hydroxyl protecting agent to replace the traditional trimethylchlorosilane hydroxyl protection methods, not only effectively prevent the silicon hydride groups with hydroxyl side-effects between, but also simplify the reaction process to achieve a response to green. Hydrosilylation synthesized double-ended hydroxyalkyl of PDMS, single-ended double-hydroxyalkyl of PDMS, as well as single-ended double-hydroxyalkyl PMTFPS.2. Surface properties of PDMS-PU segmented copolymersA. PDMS can effectively reduce surface energy of copolymer film. Copolymer membrane surface of the water contact angle increases with the PDMS content increased gradually tends to a maximum of about 110°. PDMS chain segments longer; the above phenomenon is more significant. Annealing temperature, the water contact angle is even greater, is conducive to polysiloxane chains on the surface enrichment.B. Advancing contact angle and receding contact angle increases with increasing PDMS content, contact angle hysteresis increases with the PDMS chain segments smaller reduction in the surface of hydrophilic groups are conducive to the formation of a durable low surface energy.C. All the copolymer membrane surface can be observed in 5-20nm scale, micro-phase separation structure. With the PDMS chain segment length, PDMS content increased, the micro-phase separation is significantly enhanced, micro-phase structure "double-continuous phase" to "island" structural changes. High annealing temperature is conducive to polysiloxane chains to the surface enrichment, micro-level phase separation increased, relative to district size increases.D. Elements in the coating the surface of silicon noticeable enrichment of siloxane chain segments extending toward the air interface, the changes in silicon with depth gradually decreased, when the information depth of about 10nm when the elements are still larger than the bulk composition, PDMS chain segments increased, PDMS content increased and the annealing temperature are conducive to the surface of silicon enrichment.3. Surface properties of PDMS-PU grafted copolymerA. PDMS (PMTFPS) can effectively reduce the surface energy of copolymer film. Copolymer membrane surface of the water contact angle with the increase of polysiloxane content increased gradually tends to a maximum of about 110°. In this study, within the polysiloxane composition, water contact angle and the polysiloxane chain length has little to do. Annealing temperature, the water contact angle is even greater, is conducive to polysiloxane chains on the surface enrichment.B. Advancing contact angle and receding contact angle increases with increasing PDMS content, contact angle hysteresis increases with the PDMS chain segments smaller reduction in the surface of hydrophilic groups are conducive to the formation of a durable low surface energy.C. In this article, within the scope of the study, grafted copolymer membrane surface can not form a clear micro-phase separation of nano-size, surface enrichment layer of uniform polysiloxane.D. Elements in the coating the surface of silicon noticeable enrichment of siloxane chain segments extending toward the air interface, the changes in silicon with depth gradually decreased, when the information depth of about 10nm when the elements are still larger than the bulk composition, PDMS chain segments increased, PDMS content increased and the annealing temperature are conducive to the surface of silicon enrichment.E. The introduction of fluorinated groups little effect on their surface properties. 4. The influence of surface properties, surface morphologies by linkage formA. Segmented and grafted two kinds of links means links siloxane-modified polyurethane coatings can effectively reduce the surface energy, with the PDMS content increased the surface enrichment of polysiloxane chains tends to a constant, the water contact angle to stabilize The maximum value of about 110°. The static contact angle of grafted copolymers larger than segmented copolymers, while contact angle hysteresis is more evident, showing the surface can be lower, but difficult to maintain a durable low surface energy.B. In the same composition, the segmented copolymer formed a clear link to the surface of micro-phase separation structure, the surface of Si elements is relatively small, hydrophobic groups on the surface enrichment is relatively weak.C. The performance of the surface of grafted copolymers can be lower, but difficult to maintain a durable low surface energy may be related to the nature of the high degree of freedom of polysiloxane chains, chain segment movement ability, and at the same time easy-to-surface Enrichment and surface reconstruction.更多还原