蝌蚪型POSS接枝含氟丙烯酸酯类杂化聚合物多孔膜的制备研究

以本实验室合成的3种结构的蝌蚪型POSS杂化聚甲基丙烯酸三氟乙酯(POSS-PTFEMA)、POSS杂化聚甲基丙烯酸三氟乙酯嵌段共聚聚甲基丙烯酸甲酯(POSS-PMMA-PTFEMA)及POSS杂化聚甲基丙烯酸甲酯嵌段共聚聚甲基丙烯酸三氟乙酯为成膜材质,利用呼吸图案法制备规整结构的蜂窝状聚合物多孔薄膜.利用扫描电镜(SEM)对薄膜表观形貌进行观察,分析了孔形貌的影响因素,并研究了多孔膜的疏水疏油性和耐温性.研究表明,以氯仿为成膜溶剂,3种不同结构的杂化聚合物均可以在较大的浓度范围下(5~30 mg/mL)制备规整的杂化聚合物多孔膜,膜的孔径随聚合物浓度的增大而增大;聚合物POSS-PTFEMA由于化学结构中含有最多的TFEMA结构单元,其规整性最好;相对疏水的硅片也有利于这类疏水的聚合物多孔膜的制备.所形成的多孔膜具有良好的耐温性能和疏水拒油性,其对水接触角介于98°~116°之间,对正十二烷的接触角则介于43°~66°之间.     

利用呼吸图案法制备聚(苯乙烯-b-丙烯腈)有序多孔薄膜

以自制的聚(苯乙烯-b-丙烯腈)(PS-b-PAN)嵌段共聚物为成膜材料, 采用呼吸图案法制备了有序多孔薄膜, 采用扫描电子显微镜(SEM)对薄膜形貌进行了分析, 研究了聚合物浓度、溶剂种类及共聚物结构对薄膜结构的影响. 结果表明, 薄膜表层为多孔结构, 且孔为圆形、以六方阵列形式排列; 薄膜表层下面是蜂窝状结构.以三氯甲烷(CHCl₃)为溶剂时, 在较高浓度下制备的薄膜表层孔间距较大, 蜂窝结构尺寸较小, 且形成了多层结构. 与CHCl₃为溶剂时相比, 挥发速度较快的二硫化碳(CS₂)作溶剂时制备的多孔薄膜有序性较好, 薄膜表层孔径和孔间距均较大, 蜂窝结构尺寸较小. 以没有PAN链段的聚苯乙烯大分子引发剂(PS-Cl)为成膜材料时, 制备的薄膜表层没有形成多孔结构, 而是形成了窝状结构. 同时, 通过对薄膜表层晕的研究证明了多孔薄膜表层缺陷是由水滴处于液膜下较深的位置造成的.     

呼吸图案法制备蜂窝状有序多孔薄膜及其功能化应用

呼吸图案(BF)法是一种制备微纳米级规整多孔结构的简单、廉价和高效的方法, 它以水滴为模板, 通过水滴有序排列得到蜂窝状有序多孔结构, 其孔的形貌可以通过选择不同的成膜材料和成膜环境等条件得到控制, 所以在分离膜、模板、响应性表面、催化剂、光电材料等研究领域有广阔的发展前景. 但是, 到目前为止, 人们发现由于成膜条件的不同, 多孔膜的孔形貌受多种因素影响, 规整多孔膜形貌的控制机理还不是很明确, 没有一个统一的结论. 本文结合本课题组所做工作及近五年来国内外呼吸图案法制备蜂窝状有序多孔薄膜的研究成果, 对多孔薄膜的形成过程及其影响因素、多孔膜的功能化及应用等方面进行了归纳总结, 试图揭示孔的形成及孔形貌的调控等相关规律, 希望对后续的进一步研究与应用奠定基础.     

利用Breath Figures法制备具有蜂窝状结构的 PMMA/TBT复合膜

以聚甲基丙烯酸甲酯(PMMA)和钛酸四丁酯(TBT)的氯仿溶液为铸膜溶液,采用Breath Figures法制备了蜂窝状结构的PMMA/TBT多孔阵列薄膜,采用SEM、JR、XRD对制备的多孔膜进行了表征,探讨了聚合物浓度、PMMA/TBT配比以及水解抑制剂对膜蜂窝状结构的影响.实验结果表明,起始溶液浓度为20～30m...     

水蒸汽辅助法制备PLLGA蜂窝状多孔膜

以疏水性高分子L-丙交酯-乙交酯共聚物（PLLGA）为膜材质,以十二烷基硫酸钠为添加剂,在高湿度气氛环境中使用浇铸成膜的方法制得了具有规整蜂窝状结构的薄膜,研究了环境温度、湿度和聚合物溶液浓度等因素对孔结构的影响.结果表明,表面活性剂是疏水性膜材质能否形成蜂窝状结构的关键因素.     

利用Breath Figure法制备具有Honeycomb结构的有机/无机复合膜

以聚苯乙烯和正硅酸乙酯的有机溶液为铸膜溶液, 利用Breath Figure法制备了PS/SiO2Honeycomb结构复合膜. 采用SEM对复合膜进行了形貌分析, 探讨了聚合物浓度、 PS/TEOS配比、聚合物的结构、溶剂等对膜Honeycomb结构的影响. 研究结果表明, 聚合物浓度在20～50 mg/mL, PS/TEOS质量比大于2∶1的条件下可以制备结构完整的多孔膜, 且制备的Honeycomb结构在0.8 cm2内无缺陷; 采用双羧基封端的聚苯乙烯成膜效果好于单羧基封端的成膜效果; 以氯仿和苯作为溶剂均可以制备完全Honeycomb结构的复合膜, 但以苯为溶剂制备的多孔膜孔径较大. 成膜中TEOS水解不完全, 复合膜中混杂着未完全水解的TEOS以及SiO2. EDS面扫描分析表明, Si和O均匀地分散在复合膜中.     

扩散致相转化法制备结晶性聚合物多孔膜

介绍了扩散致相转化法制备结晶性聚合物多孔膜的研究现状。其三元等温成膜体系的相图包含液-液分相和固-液分相两种相分离方式,是理解成膜过程的重要工具,总结了成膜机理和膜的结构形貌：单纯S-L相分离生成粒子状对称膜结构;单纯L-L相分离生成蜂窝状非对称膜结构;两种相分离方式竞争发生将生成多样的混合膜结构。铸膜液浓度、非溶剂种类、铸膜溶剂组成、凝胶浴组成、制膜温度是影响膜结构形貌的主要因素。     

聚乳酸组织工程支架结构的精密调控

采用糖球模板法结合热致相分离技术,制备了孔径尺寸、内连通度及孔隙率高度可控的左旋聚乳酸(PLLA)支架材料,并通过扫描电镜(SEM)、红外光谱(FTIR)以及示差扫描量热法(DSC)对其空间结构及性能进行了系统研究.支架材料孔径从50μm到800μm及内连通孔径从10μm到200μm连续可调,微观孔壁结构根据不同溶剂可形成各异的微纳米结构.支架的制备对PLLA化学结构无显著影响,但相分离过程会不同程度地降低PLLA的结晶度.     

静电纺制备纳米孔结构聚乳酸(PLLA)超细纤维

采用静电纺丝法制备了孔径为40～150 nm的PLLA纳米孔结构超细纤维,纳米孔不仅分布在纤维表面,而且存在于纤维内部.通过扫面电镜观察了纤维表面形貌.探讨了混合溶剂二氯甲烷/N,N-二甲基甲酰胺的比例、PLLA浓度、电场强度对PLLA纤维纳米孔大小、分布密度、深度的影响.结果表明通过调节PLLA溶液性质和纺丝参数,PLLA纤维的表面形貌可以在3种状态即光滑无孔、疏浅凹坑、密集深孔之间可控.二氯甲烷/N,N-二甲基甲酰胺比例为1∶4,PLLA浓度9%,电场强度1 kV/cm,环境温湿度分别为30℃和52%,静电纺丝所得PLLA超细纤维表面孔洞直径为150 nm,孔洞分布密集.纳米孔PLLA纤维形成的主要机理是由于静电纺丝过程中溶剂的快速挥发引起纤维表面温度急剧降低导致热致相分离而产生多孔结构.PLLA纤维膜的疏水性与纤维表面孔洞结构密切相关,纤维膜接触角最高可达146.6°.由于PLLA纤维的多孔结构,这种高疏水性的PLLA纤维膜能够快速、大量地吸油,90 s内吸收柴油达到90 g/g,25 min内可以达到145 g/g.     

以Pluronics~为第二组分制备聚乳酸蜂窝状规整多孔薄膜

以聚乳酸(PLA)为成膜材料,以两亲三嵌段共聚物PEO-PPO-PEO(Pluronics)为第二组分,利用水辅助法成功地制备了聚乳酸蜂窝状多孔膜.研究了环境湿度、溶液浓度和所用PLA分子量对多孔膜结构的影响.结果表明,加入第二组分PEO-PPO-PEO能有效地促进规整蜂窝结构的形成.蛋白质吸附实验结果进一步证明了PEO-PPO-PEO组分在孔洞内壁的富集,由此构建了阻抗蛋白质吸附的图案化功能结构表面.     

聚苯乙烯-co-聚(2,3,4,5,6-五氟苯乙烯)共聚物: 合成及其多孔薄膜的制备

利用原子转移自由基聚合(ATRP)方法, 分别在三氟甲苯、含氟离子液体以及三氟甲苯/含氟离子液体混合溶剂体系中合成了聚苯乙烯-co-聚(2,3,4,5,6-五氟苯乙烯)(PS-co-PPFS)共聚物, 通过¹H NMR、¹⁹F NMR、元素分析以及凝胶渗透色谱法(GPC)对所得聚合物的分子链结构和组成进行了分析和表征. 随后, 利用静态呼吸图法分别在CS₂, CHCl₃ 和CH₂Cl₂ 中制备了有序多孔薄膜, 用扫描电子显微镜(SEM)观察其表面形貌, 并与利用分子量大小相当的聚苯乙烯均聚物(PS)制备的多孔薄膜进行了对比. 研究结果表明: 在三氟甲苯和含氟离子液体溶剂体系中, 均可利用ATRP 聚合方法获得窄分子量分布的PS-co-PPFS 共聚物(M_n＝5200～7900 g·mol^-1, i>M_w/M_n＝1.12～1.22). 对聚合物薄膜的扫描电子显微镜(SEM)观察和分析显示: 分别以CS₂, CHCl₃ 和CH₂Cl₂ 作为溶剂, 利用静态呼吸图法均可制备出PS-co-PPFS 共聚物多孔薄膜. 然而, 与在CHCl₃ 和CH₂Cl₂ 中制备的PS 均聚物多孔薄膜的表面形貌不同的是, PS-co-PPFS 共聚物多孔薄膜呈现出无序排列、平均孔径大小不同的两种孔结构; 在CHCl₃ 中制备所得薄膜的孔结构有序性相对较好, 两种孔的平均孔径分别为0.75 和0.37 μm.     

Porous thin films based on photo-cross-linked star-shaped poly(D,L-lactide)s

Self-assembly processes and subsequent photo-cross-linking were used to generate cross-linked, ordered microporous structures on the surfaces of well defined four-arm star-shaped poly(D,L-lactide) (PDLLA) thin films. The four-arm star-shaped PDLLAs were synthesized using an ethoxylated pentaerythritol initiator. Solutions of the PDLLAs were cast in a humid environment, and upon solvent evaporation, ordered honeycomb structures (or breath figures) were obtained. Correlations between molar mass, polymer solution viscosity, and pore dimensions were established. The average pore dimension decreased with increasing polymer solution concentration, and a linear relationship was observed between relative humidity and average pore dimensions. Highly ordered microporous structures were also developed on four-arm star-shaped methacrylate-modified PDLLA (PDLLA-UM) thin films. Subsequent photo-cross-linking resulted in more stable PDLLA porous films. The photo-cross-linked films were insoluble, and the honeycomb structures were retained despite solvent exposure. Free-standing, structured PDLLA-UM thin films were obtained upon drying for 24 h. Ordered microporous films based on biocompatible and biodegradable polymers, such as PDLLA, offer potential applications in biosensing and biomedical applications.     

Tunable morphology of 2D honeycomb-patterned films and the hydrophobicity of a ferrocenyl-based oligomer

Honeycomb-patterned polymer films with tunable pore size and regularity of ordered two- or three-dimensional hexagonal arrays have met with widespread interest in recent years in different areas, for instance as separation and superhydrophobic materials. Herein, 2D honeycomb-patterned films of amphiphilic ferrocenyl-based oligomer with cholesterol as side chains were prepared by the breath-figure method on solid surfaces and their surface-wetting behavior were tested. These films can be simply prepared by spreading a mixture of polymer and organic solvents on a solid surface under moist airflow and at an air/water interface without any extra moist airflow. An ordered 2D hexagonal array of pores with monodisperse size distribution can be obtained over a large area by changing various influencing factors, including humidity, wet volume, concentration, selective solvent, and spreading method, which provides a facile route to regulate the morphology of patterned porous films. The surface-wetting behavior indicates that a higher hydrophobicity of the ferrocenyl-based oligomer honeycomb films can be obtained by modulating the pore size and regularity. It is expected that this could promote the potential application of ordered porous polymer films in hydrophobic materials and biochemistry.     

Porous polymer films and honeycomb structures based on amphiphilic dendronized block copolymers

Fabrication of honeycomb patterned films from our synthesized amphiphilic dendronized block copolymer by "on-solid surface spreading" method and "on-water spreading" method was reported for the first time in this paper. The comparison of the two methods indicated honeycomb-patterned films with smaller size, and larger surface density of micropores can be fabricated by spreading on water but with lower regular arrangement. Furthermore, several influencing factors on the formation of the honeycomb structure and the different morphologies, such as the concentration of the copolymer solution and the relative humidity in the atmosphere and the substrates, were investigated. The results showed that comparably high relative humidity from 80% to 95% was needed, and the mica plate as a spreading substrate was suitable to form orderly porous films for such a copolymer. The best ordered pattern could be formed from the copolymer with concentration of 1.00 mg/mL at the relative humidity of 85% using a mica plate. Besides, strong periodicity, regularity, and a large, defect-free area were notable, which made this structure extremely interesting for applications for templated molecular objects formed via intramolecular metal or metal oxide synthesis.     

Preparation of porous biodegradable PLLA with tunable pore size through simple variation of PEG/PLLA-blend crystallization conditions

In this study, porous poly(L-lactic acid) (PLLA) films are prepared via a facile and low-cost approach using poly(ethylene glycol) (PEG) and solution casting. In contrast to most studies, the PEG/PLLA samples are further processed under different crystallization conditions (i.e., different PLLA crystallization temperatures) before PEG removal. As the PEG is extracted via solvent at higher PLLA crystallization temperatures, the resultant PLLA samples have larger pores. Interconnected fibrillar-shaped pores are found in all systems, and the fibrillar-porous structure width is ~150 nm–1.2 μm, as observed via scanning electron microscopy. These pore sizes can be tuned by adjusting the blend composition and crystallization temperature. In addition, PEG/PLLA blends are subjected to hydrolytic degradation analysis according to their crystallization conditions. Higher PLLA crystallization temperature yields higher PLLA crystallinity and larger pores, as well as reduced surface interaction with water. Therefore, the PLLA degradation rate is decreased. The developed PLLA films have potential applications in drug delivery and tissue engineering.     

聚苯乙烯-嵌段-聚丁二烯有序多孔膜在可收缩膜上的形变研究和光学性质

利用溶剂散逸自组装法在潮湿的条件下,制备了聚苯乙烯-聚丁二烯嵌段聚合物（PS-b-PB）有序多孔膜。 利用聚乙烯可收缩膜将PS-b-PB多孔膜进行两次收缩,形成小孔径的有序多孔膜。 通过收缩,膜上的孔由圆形变为长方形或者梭形,孔的尺寸从微米级收缩至亚微米级。 利用扫描电子显微镜对膜收缩过程中2种形状产生的机理进行了研究。 结果表明,PS-b-PB结合了聚苯乙烯（PS）和聚丁二烯（PB）两个均聚物的优点,收缩后仍然保持膜结构的平整性,从而将不可见的热场变化转变为可见的光学变化。     

甲醇气氛静态呼吸图法制备蜂窝状有序多孔膜

以原子转移自由基聚合方法合成的聚二甲基硅氧烷-b-聚苯乙烯(PDMS-b-PS)为铸膜材料,在静态呼吸图的基础上,首次在甲醇氛围下利用PDMS-b-PS的二硫化碳溶液铸膜得到了高度规整的蜂窝状有序多孔结构.研究了聚合物溶液浓度对孔径的影响,并与水蒸汽氛围制备的孔结构进行了比较.结果表明,甲醇气氛下制备的多孔膜的孔径比水蒸汽氛围下的大,且孔的断面形貌呈“U”形;孔径随着溶液浓度的增大而减小.该研究有利于呼吸图法制备有序结构材料技术的进一步发展,有助于人们更加准确与全面地认识呼吸图机理.     

Self‐Organization of Honeycomb‐like Porous TiO2 Films by means of the Breath‐Figure Method for Surface Modification of Titanium Implants

This study describes a facile breath‐figure method for the preparation of honeycomb‐like porous TiO₂ films with an organometallic small‐molecule precursor. Multiple characterization techniques have been used to investigate the porous films and a mechanism for the formation process of porous TiO₂ films through the breath‐figure method is proposed. The pore size of the TiO₂ films could be modulated by varying the experimental parameters, such as the concentration of titanium n‐butoxide (TBT) solution, the content of cosolvent, and the air flow rate. In vitro cell‐culture experiments indicate that NIH 3T3 fibroblast cells seeded on the honeycomb‐like porous TiO₂ films show good adhesion, spreading, and proliferation behaviors, which suggests that honeycomb‐like porous TiO₂ films are an attractive biomaterial for surface modification of titanium and its alloys implants in tissue engineering to enhance their biocompatibility and bioactivity.