节点文献

纤维织物基有机(氟)硅超疏水表面的制备与性能研究

Preparation and Property of (Fluoro) Polysiloxane Superhydrophobic Surfaces on Cotton Fabrics

【作者】 郝丽芬

【导师】 安秋凤;

【作者基本信息】 陕西科技大学 , 应用化学, 2013, 博士

【摘要】 润湿性是固体表面的重要性能之一,由固体表面的化学组成和微观形貌共同决定,因此,通过改变固体表面自由能和粗糙度可实现对固体表面润湿性的调控。无机-有机纳米杂化材料,结构独特,可赋予材料新的性能,一直是仿生超疏水研究领域的热点。通常,固体表面微观结构的粗糙化可通过无机纳米材料实现,但界面表层结构粗糙的低表面能聚合物对构筑微观多尺度粗糙界面的作用也不容忽视。另外,在无机-有机杂化材料中,如何实现无机纳米粒与聚合物的有效键合,改善两者的相容性、增加纳米粒在有机相中分散稳定性,并解决杂化材料在超疏水表面应用中的多功能化及耐久稳定性等问题,是值得探讨的一个科学问题。基于有机氟硅聚合物的低表面能特性以及超疏水界面构筑中的“荷叶效应”,本文利用分子设计原理并借助不同化学反应先合成了系列低表面能有机(氟)硅聚合物,然后通过化学接枝或结构修饰,将不同结构的硅溶胶纳米粒键入有机(氟)硅聚合物主(侧)链,从而制得了系列纳米杂化氟硅聚合物,并将其负载固化在纤维基质表面从而构筑了一系列兼具柔软与耐久性的超疏水表面。论文具体工作如下:1.纳米SiO2杂化十八醇酯基聚硅氧烷的合成及其构筑的超疏水棉织物利用含氢硅油(PHMS)、甲基丙烯酸十八醇酯(SMA)与烯丙基缩水甘油醚(AGE)的硅氢化加成反应,将长碳链酯基和环氧基同时引入聚二甲基硅氧烷侧链,首先制得了一种梳状十八醇酯基/环氧基共改性聚硅氧烷(PSAMS)。其次,在碱性条件下将正硅酸乙酯水解缩合、再用氨丙基三乙氧基硅烷(KH-550)改性,制得了一系列平均粒径为55.54~231.4nm、单分散、球状、且呈无定形结构的氨丙基改性硅溶胶(H2N-SiO2)。在此基础上,将PSAMS与H2N-SiO2进行环氧开环反应,从而制得了一类纳米SiO2杂化十八醇酯基聚硅氧烷(PSAMS-SiO2)。用IR、1H/13C-NMR、SEM、AFM、XPS、接触角测量仪等仪器对有关中间体及产物的结构、膜形貌及性能进行了研究和表征,探讨了反应条件,确定了PSAMS-SiO2的制备工艺。然后,以棉纤维织物作载膜基质,并采用浸轧烘整理工艺,一步制得了兼有柔软与耐久性的超疏水织物。研究表明,PSAMS膜微观上呈高分子刷粗糙膜结构,且十八醇酯基在PSAMS中引入量越大,该膜粗糙化程度越大。H2N-SiO2的粒径、接枝量及PSAMS的结构等对目标产物PSAMS-SiO2的形貌及性能有影响。在杂化体系中,H2N-SiO2的引入可致PSAMS-SiO2的微观膜形貌进一步粗糙化并呈现多相结构,且可提高杂化膜的耐热稳定性及疏水性能(以水在该表面的静态接触角WCA表示)。当H2N-SiO2的粒径为176.2nm、SiO2接枝量达到PSAMS质量的6.3%,PSAMS-SiO2膜表面的均方根粗糙度(Rq)从杂化前的0.370nm增加至4.066nm,而WCA则达到了158.5°、滚动角下降为10°。另外烘焙过程中,聚硅氧烷分子中Si-OH、C-OH与基质纤维素羟基之间的交联固定作用可赋予PSAMS-SiO2膜良好的耐水洗性,避免使用中SiO2纳米粒的脱落,因而,织物经20次皂洗后,WCA依然可达140°。用Cassie模型分析PSAMS-SiO2整理后的棉织物,发现在处理后织物界面上,空气在该复合接触界面所占比例达89%,显然大量空气嵌留在织物的微观粗糙结构中,使水滴在其表面呈悬浮态,是该界面产生超疏水的内在原因。基于此,提出了PSAMS-SiO2在棉纤维表面的定向排列成膜方式。2.纳米杂化梳状有机氟硅共聚物的合成及构筑的超疏水棉织物首先,采用硅氢化加成反应,将长链全氟烷基、环氧基引入聚甲基三氟丙基硅氧烷侧链中,制备了一类梳状结构的有机氟硅共聚物(PFAMS),然后将其与H2N-SiO2进行反应,制得了一类纳米SiO2杂化有机氟硅共聚物(PFAMS-SiO2),并用于超疏水棉织物的构筑。采用同上的方法对中间体及产物的结构、膜形貌及性能进行了研究和表征。研究发现,与PSAMS-SiO2相比,PFAMS-SiO2整理后的棉织物其超疏水性能更佳。当SiO2平均粒径为204.7nm,SiO2接枝率为9.7%时,PFAMS-SiO2膜的超疏水性能最佳,WCA可达到161.5°,滚动角降至9°。显然,长链氟烷基(Rf)的趋表富集及定向排列作用更有利于降低PFAMS-SiO2处理后棉纤维表面的表面能;而且,与PSAMS相比,PFAMS膜的均方根粗糙度更大,Rq达0.567nm;SiO2纳米粒可进一步提高PFAMS-SiO2膜的纳米级粗糙度,Rq增至4.104nm。低表面能Rf链与微观多尺度粗糙基质的结合更有利于PFAMS-SiO2表现出大的接触角及较小的滚动角。最后,通过Cassie方程对棉纤维表面PFAMS-SiO2膜的超疏水机理分析可知,空气在该复合接触界面所占比例达91%,由此说明PFAMS-SiO2处理后的棉织物表面产生了类荷叶表面的微纳米凸起,该微观粗糙膜结构中空气垫的存在使水滴只与膜的顶端相接触,因而,PFAMS-SiO2处理的棉织物超疏水性能优良。3.以纳米SiO2杂化交联网状聚硅氧烷构筑超疏水棉织物首先,由八甲基环四硅氧烷(D4)、四甲基四乙烯基环四硅氧烷(DVi4)和(3-缩水甘油醚丙基)-1,1,3,3-四甲基二硅氧烷(DEp2)的碱性平衡化反应制得了乙烯基端环氧硅油(Ep-PDMS-Vi)前体原料;然后将其与PHMS进行硅氢化加成反应,制得了一类环氧基封端的网状聚硅氧烷(Ep-JNPDMS)中间体;再将其与KH-550进行反应,制得了一类疏水性含硅烷氧基的网状聚硅氧烷(JNPDMS);在此基础上,利用硅烷氧基水解产生的Si-OH与硅溶胶间的原位缩合反应制得了一系列低成本、环保型纳米杂化交联网状结构的聚硅氧烷(JNPDMS-SiO2)。在IR、XPS等对其进行结构表征和分析的基础上,重点对JNPDMS-SiO2在纤维表面的耐热稳定性、微观形貌、成膜机理及疏水性能进行了研究。结果发现,原位缩合法可有效提高JNPDMS-SiO2中SiO2纳米粒的接枝率,最大接枝率达23%。而且JNPDMS的交联网状结构更有利于提高JNPDMS-SiO2的耐热稳定性和疏水性能。其次,JNPDMS膜微观上呈相对平整、致密的均一相结构,在2×2μm2扫描范围内,JNPDMS硅膜Rq较小,为0.256nm。在杂化体系中,SiO2的引入可致JNPDMS-SiO2膜呈现参差不齐的粗糙形貌,且呈多相结构,在其表面有大量高低不同的峰包存在,JNPDMS-SiO2膜的Rq达4.528nm。由此可见,JNPDMS-SiO2处理的棉纤维表面特殊的“仿荷叶”微纳米粗糙结构和疏水性JNPDMS协同作用赋予了纤维基质柔软、耐久超疏水性能。因此,当SiO2粒径为134.3nm,JNPDMS-SiO2用量为0.5%时,经JNPDMS-SiO2处理的棉织物超疏水性能最佳,WCA达158.0°,滚动角降至9°,且织物经20次皂洗后,WCA仍可达144°。最后,我们提出了JNPDMS-SiO2在棉纤维基质表面的成膜作用机理。4.以纳米SiO2杂化长链氟烷酯基三氟丙基共改性聚硅氧烷制备超疏水棉织物采用与PFAMS相同的制备方法,制得了一类侧链携带有长链氟烷酯基/三氟丙基/环氧基的聚硅氧烷;再将其与KH-550进行反应,制得了一类梳状结构的长链氟烷酯基/三氟丙基/硅乙氧基聚硅氧烷(FPFAS)。然后,利用FPFAS中硅乙氧基水解产生的Si-OH与硅溶胶间原位缩合反应,制得了一类纳米SiO2杂化长链氟烷酯基/三氟丙基改性聚硅氧烷(FPFAS-SiO2),并将其用于超疏水织物的构筑,确定了制备工艺条件。重点研究了PFAMS、FPFAS-SiO2的微观形貌及其分子结构与疏水性能的关系。研究发现,与PFAMS膜形貌相比,FPFAS硅膜也呈微观粗糙膜(Rq达0.650nm)、相分离结构,其表面有长链氟烷酯基所致的大量高度不同的大峰包存在,这与PFAMS膜表面长链全氟烷基产生的细而高的尖峰明显不同。由此推测,长链氟烷酯基趋表能力更强,而且受氟、硅相容性差的影响,长链氟烷酯基间更易相互靠拢形成大的聚集体并伸向空气,SiO2纳米粒的引入可进一步提高FPFAS-SiO2膜的纳米级粗糙度(Rq达5.293nm),更有利于FPFAS-SiO2在纤维表面发生定向排列,进而提高其疏水性能。因此,当纳米SiO2粒径为134.3nm,FPFAS-SiO2中SiO2接枝率达24.3%,FPFAS-SiO2用量为0.5%时,水在FPFAS-SiO2表面的WCA最大,达163.5°,滚动角为7°。最后,用Cassie模型对FPFAS-SiO2处理的棉织物表面的超疏水机理分析可知,FPFAS-SiO2表面,气-液界面所占面积高达91%,再次证实,FPFAS、纳米SiO2粒子和棉纤维本身的协同作用使FPFAS-SiO2处理的棉纤维表面产生了微米-纳米-分子级多尺度微观粗糙结构,这也是构筑仿生超疏水表面的关键所在。

【Abstract】 Wettability, which is determined by chemical compositions andmicrostructure of one solid surface, is an important property for solid surface,and thus can be well controlled via the exact regulation of surface free energyand roughness. Due to their unique structure, inorganic-polymer hybridmaterials can endow the matrix with novel properties and thus have become oneof the hot topics in fabrication of the biomimetic super-hydrophobic surfaces. Itis generally recognized that microscopic roughness on solid surface couldmainly be realized by the inorganic nano-materials. However, it should not beignored what design and synthesis of hydrophobic polymeric films withmicroscopic roughness plays in construction of surface with multi-scaleroughness. Furthermore, how to achieve the chemical bonds between inorganicnano-particle and polymer, to improve their compatibility and thenano-particle’s dispersity, and to finally construct superhydrophobic hybridcoatings on cotton fabrics/fibers surface with multi-function and high durabilityis a worthy scientific theme to explore.Therefore, on basis of the “Lotus effect” principle in fabrication ofsuperhydrophobic surface and the low surface free energy characteristic oforganic fluorosilicone polymer, we exploited the principle of molecular designand series of chemical reactions to first prepare several organic fluorosiliconepolymers, and then to synthesize series of fluorosilicone nanocomposites viachemical grafting or structural modification in which silica nanoparticles ofvarious structures were bonded onto pendant groups of the fluorosilicone polymers. Finally, we fabricated the biomimetic super-hydrophobic surfaces oncotton with softness and high durability via simple dip-coating of thosenanocomposites. The main research works are listed as followings:1. Preparation of stearyl methacrylate modified polysiloxane/silicananocomposite and fabrication of superhydrophobic cotton fabric from it.Comb-like stearyl/epoxy groups modified polysiloxane (PSAMS) wasfirstly prepared by hydrosilylation of stearyl methacrylate (SMA), allylglyeidylether (AGE) and polyhydromethylsiloxane (PHMS). Then a series of themonodispersed and amorphous aminopropyl modified silicas (H2N-SiO2) withthe average particle sizes from55.54to231.4nm were fabricated through thehydrolysis-condensation reaction of tetraethyl orthosilicate under alkalinecondition followed by the modification of aminopropyl triethoxysilane(KH-550). At last, a stearyl methacrylate modified polysiloxane/silicananocomposite (PSAMS-SiO2) was synthesized from graft copolymerization ofamino-modified silica and PSAMS. Structures of the intermediates and the finalproducts, their film morphology and properties were characterized by IR,1H/13C-NMR, SEM, AFM, XPS, and contact angle meter, repectively. Thereaction conditions were discussed and the preparation technology of thePSAMS-SiO2was ultimately established. Then, a superhydrophobic cottonfabric with softness and high durability was constructed via one-stepimmersing-padding-baking processes. Results indicated that film morphology ofthe PSAMS presented a coarse film of the molecular sieve pattern, and more theamount of the imported stearyl ester groups were, rougher the PSAMS film was.Particle size and graft ratio of the H2N-SiO2as well as the PSAMS structureplayed an important role in the morphology and performance properties of theresultant PSAMS-SiO2. In the hybrid hierarchy, fine film morphology of thePSAMS-SiO2could be further roughened by introduction of H2N-SiO2anddisplayed a multi-phase pattern, which could enhance the hydrophobicity andthe thermal stability of the hybrid film. While the average diameter of H2N-SiO2was176.2nm and the grafting ratio of SiO2attained6.3wt%based on the massof PSAMS, the root-square-mean roughness (Rq) of the PSAMS-SiO2filmcould be increased from0.370nm prior to hybridization to4.066nm, and thestatic water contact angle (WCA) and the roll-off angle on the treated fabric could reach to158.5°and reduce to10°, respectively. During the baking process,the crosslinking and immobilizing effects between the Si-OH, C-OH groups ofthe polysiloxane molecules and hydroxyl groups of cotton cellulose can avoidthe detachment of nano silica and afford the PSAMS-SiO2film with goodwashing durability. Thus, WCA could still retain140°after20cycles ofsoaping.Finally, the superhydrophobic mechanism of the PSAMS-SiO2hybrid filmon the cotton fibers surface had been interpreted by the Cassie’s theoreticalmodel. The area portions of the liquid/vapor contact area was89%on thecomposite interface of the PSAMS-SiO2treated fabric surface and there were alot of gases embedded in air pockets from the multi-scaled rough cottonsurfaces, which impelled the water droplets as the suspended state on cottonsurface and those should be the inherent reason of acquiring thesuperhydrophobic effect. Hereby, the directional arrangement and film-formingmanners of the PSAMS-SiO2on cotton fiber surface are proposed.2. Synthesis of comb-like organo-fluorosilicone copolymer/silicananocomposite and construction of superhydrophobic cotton fabric from it.A novel comb-like fluorosilicone copolymer (PFAMS) was firstly preparedby hydrosilylation of perfluorooctyl ethylene (PFOE), allylglyeidyl ether (AGE)and polymethyltrifluoropropylhydrosiloxane (PFHMS). Then series offluorosilicone copolymer/silica nanocomposites (PFAMS-SiO2) with combstructure were synthesized from graft copolymerization of H2N-SiO2andPFAMS and used in fabrication of superhydrophobic cotton fabrics. Structuresof the intermediates and the final products, their film morphology and propertieswere characterized using above the same methods. Results indicated that thesuperhydrophobicity of the treated cotton fabric by PFAMS-SiO2was superiorto that of the PSAMS-SiO2treated fabric. When the average diameter of thesilica sol was204.7nm and the graft ratio of silica was9.7%, the bestsuperhydrophobicity was obtained with WCA of161.5°and roll-off angle of9°.It was probably originated from the facts that the fluoroalkyl groups was proneto migrate into the surface compared to long-chain alkyl, and thus, the surfacefree energy of the treated fabric was reduced to a lower extent. Furthermore, bycomparison with PSAMS, RMS of the PFAMS was larger and its Rq could attain0.567nm on silicon wafer. Nanoscale roughness of the PFAMS-SiO2could be further enlarged by introduction of SiO2particles and its Rq couldachieve4.104nm. Thus the combination of the long chain fluoroalkyl with lowsurface free energy and the multi-scaled rough surface would preferablyengender the bigger WCA and the smaller roll-off angle. At last, thesuperhydrophobic mechanism of the PFAMS-SiO2hybrid film on the cottonfibers surface had been interpreted by the Cassie’s theoretical model and thearea portions of the liquid/vapor contact area was91%on the compositeinterface of the PFAMS-SiO2treated fabric surface, which implies thatmicro-nano embossments resembling lotus leaf surface have been produced onthe PFAMS-SiO2treated cotton surface and the air pockets in thosecharacteristic dual-scaled rough films make the water droplets contact the top ofthe films, therefore, superhydrophobicity of the PFAMS-SiO2treated cotton ismore favorable.3. Fabrication of superhydrophobic cotton fabric using polysiloxane/SiO2hybrid material with crosslinked network structure.Firstly, epoxy group-terminated polyvinylmethylsiloxane precursors(Ep-PDMS-Vi) were prepared via the alkaline equilibration reaction ofoctamethylcyclotetrasiloxane (D4),2,4,6,8-Tetramethyl-2,4,6,8-tetravinyl-cyclotetrasiloxane (DVi4), and3-glycidyl ether propyl-1,1,3,3-tetramethyldi-methylsiloxane (DEP2). Then, a sort of epoxy group-terminated polysiloxaneintermediates with network structure (Ep-JNPDMS) was acquired byhydrosilylation of Ep-PDMS-Vi and PHMS. Next, those Ep-JNPDMS wouldreact with KH-550to produce series of alkoxy silane-containing hydrophobicpolysiloxane with network strucuture (JNPDMS). On this basis, a series of lowcost and environmental benign polysiloxane/SiO2hybrid materials withcrosslinked network structure (JNPDMS-SiO2) were made by in-situcondensation reaction among silicon hydroxyls. IR and XPS were utilized tocharacterize the JNPDMS-SiO2. The emphasis was put in this context onthermal stability, micro-morphology, film-forming mechanism andhydrophobicity of the JNPDMS-SiO2film on fiber surface. Results indicatedthat the grafting ratio of SiO2onto the JNPDMS-SiO2skeletons was effectivelyenhanced by the in-situ condensation method and it could maximumly attain 23%. Furthermore, that crosslinked network structure of the JNPDMS would bebeneficial to the enhancement of thermal stability and hydrophobicity of theJNPDMS-SiO2. AFM result demonstrated that the characteristic crosslinkednetwork of JNPDMS could form a homogeneous, smooth and dense film on theimitated cotton fiber surface with RMS of0.256nm in2×2μm2scanning range.However, in hybrid system, fine film morphology of the JNPDMS-SiO2couldbe greatly roughened by introduction of SiO2and displayed an irregular andmulti-phase pattern. There were many peaks and hills with different levels andthus Rq of the JNPDMS-SiO2could reach to4.528nm. Those showed thatdurable superhydrophobic and soft properties of the treated fabric are ascribedto the synergistic effect of the hydrophobic JNPDMS and micro-nanoembossments resembling lotus leaf surface resulting from the JNPDMS-SiO2treated cotton fiber surface. While the average particle size of SiO2was134.3nm and the dose of the JNPDMS-SiO2was0.5%, the superhydrophobicity ofthe JNPDMS-SiO2treated cotton was the best and WCA as well as roll-off angleon its surface could attain158.3°and9°, respectively. WCA could still reach144°after20cycles of soaping. Finally, the film-forming mechanism of theJNPDMS-SiO2hybrid material on the cotton fibers surface has been furtherproposed.4Fabrication of superhydrophobic cotton fabric from perfluoroalkylacrylate and trifluoropropyl modified polysiloxane/SiO2hybrid material.The same preparation method with the PFAMS was implemented toprepare the polysiloxanes with pendant perfluoroalkyl ester, trifluoropropyl, andepoxy groups which then were reacted with KH-550to produce a series ofcomb-like perfluoroalkyl ester/trifluoropropyl/ethoxy silane containingpolysiloxanes (FPFAS). Subsequently, a kind of perfluoroalkyl ester/ethoxysilane modified polytrifluoropropylsiloxane silica hybrid materials(FPFAS-SiO2) were successfully synthesized via in-situ condensation reaction.Finally, the FPFAS-SiO2was used in fabrication of the superhydrophobic cottonfabric and the optimal preparation process was ultimately established. Therelationship between the molecular structure and micro-morphology of thePFAMS and PFAMS-SiO2and their hydrophobicity was chiefly investigated.Results demonstrated that the FPFAS film also presented a phase-separated and micro-rough pattern with Rq of0.650nm by comparison with PFAMS film.There were vast and large peaks with different levels on silicon waferoriginating from the perfluoroalkyl ester groups and that manner was muchdifferent from thin and high peaks of the perfluoroalkyl on the PFAMS film inevidence. It is speculated that capability of the perfluoroalkyl ester to beenriched at the surface is preferably strong. In addition, due to the greatimmiscibility between fluorine and silicon, the perfluoroalkyl ester groups areprone to close up each other and then to form big aggregates directing at theoutmost. Nanoscale roughness of the FPFAS-SiO2can be further improved byintroduction of SiO2particles and its Rq can achieve5.293nm, immdiately, anddirectional arrangement of the FPFAS-SiO2on fiber surface will be profitablygenerated. Thus, its hydrophobicity is thereby enhanced. While the optimaldiameter of nano silica was134.3nm, and the graft ratio of nano silica inFPFAS-SiO2could attain24.3%as well as the dose of the FPFAS-SiO2was0.5%, the superhydrophobic cotton fabric with WCA of163.3°and roll-offangle of7°was fabricated.Ultimately, the superhydrophobic mechanism of the FPFAS-SiO2hybridfilm on the cotton fibers surface had been analyzed by the Cassie’s theoreticalmodel and the area portions of the liquid/vapor contact area was91%on thecomposite interface of the FPFAS-SiO2treated fabric surface, which furtherimplies that the synergistic effect of the micro-rough FPFAS and FPFAS-SiO2,and the cotton fiber itself make the FPFAS-SiO2treated cotton fiber surfaceengender a multi-scaled roughness, which is the key point in fabrication ofbionic superhydrophobic surface.

节点文献中: 

本文链接的文献网络图示:

本文的引文网络