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。     

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.     

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-organized microporous structures based on surfactant-encapsulated polyoxometalate complexes

Self-organized microporous structures based on a series of surfactant-encapsulated polyoxometalate complexes (SECs) have been prepared by using ordered condensed droplets as a template. Among these structures, ordered honeycomb structures were obtained and characterized in detail by taking (DODA)(12)H[Eu(SiW(11)O(39))2] (SEC-1) as an example. Optical microscope, atomic force microscopic, and scanning electron microscopic measurements confirmed the formation of three-dimensional microporous structure, in which the top surface shows a highly ordered honeycomb structure. As compared to common solvent-casting films, the corresponding honeycomb films are more hydrophobic and possess more ordered lamellar structures. Both the wettability and the size of SECs exert significant influence on the formation of microporous structures. The proper hydrophobicity of SECs was proposed to be an essential factor for the formation of honeycomb films, and large-sized SECs are favorable for the fabrication of highly ordered honeycomb structures. The conditions for the formation of different surface morphologies have been discussed in terms of the contact angle of SECs at the interface between water and chloroform, and a contact angle slightly greater than 90 degrees is found to be a prerequisite for the formation of honeycomb structures. The results reported in this paper not only help to further comprehend the mechanism of the formation of honeycomb structures, but also provide some guidance for the design of ordered microporous films based on organic/inorganic hybrid materials, exemplified by the organic/nanoparticle complexes.     

智能蜂窝状有序多孔薄膜：体系构建、响应性能及应用探索

蜂窝状有序多孔膜是一种典型的具有微、纳米尺寸的图案化高分子薄膜材料,在超疏水表面、光电材料、组织工程、生物医学、传感器等领域都具有良好的应用前景。表面形貌或性质具有可逆刺激响应特性的智能型多孔膜不仅拥有常规多孔膜的性能,而且还拥有独特的"开-关"功能,因此受到广泛关注。本文回顾了智能有序多孔膜近年的研究进展,重点对其体系构建、响应方式、机理、性能和相关应用进行了归纳与分析,评述了不同刺激响应多孔膜的特点及优劣势,探讨了智能多孔膜的优化设计及提高响应性能等问题,指出了目前面临的挑战,并展望了未来的发展方向。     

漆酚醛胺聚合物多孔膜的制备

以漆酚醛胺聚合物(UFDP)为成膜材料,利用水辅助自组装的固体基板展开法和水面展开法制备了漆酚醛胺聚合物多孔膜.研究了在静态(即不在聚合物表面吹扫氮气)高湿度环境下聚合物溶液浓度、环境湿度和固体基板等因素对多孔膜形貌的影响.结果表明,水面展开法更有利于形成单层的多孔膜而固体基板展开法得到的是多层的多孔膜.当UFDP聚合物浓度为6.0 mg/mL,环境相对湿度为90%时,用水面展开法制得的单层多孔膜的孔径分布较均匀.     

Improved hydrolytic stability of poly(dl-lactide) with epoxidized soybean oil

The multi-arm star polymer (ESOPLA) was obtained by ring-opening polymerization of dl-lactide using multifunctional epoxidized soybean oil (ESO) as an initiator in the presence of a stannous actuate (SnOct₂) catalyst. Gel permeation chromatography with multi-angle laser light scattering (GPC-MALLS), FTIR, ¹H NMR, thermal analysis and in vitro degradation were used to qualitatively characterize the synthesized polymers. The results revealed that ESO plays an important role in increasing the molecular weight, polymerization rate and monomer conversion rate. Degradation analysis demonstrated that the decrease in molecular weight and the weight loss ratio of the star-shaped ESOPLA were lower than that of linear poly(dl-lactide) (PDLLA). The surface topography of pre- and post-degradation materials was characterized by scanning electron microscopy (SEM). These SEM images showed that the linear PDLLA films underwent water erosion more readily than the star-shaped polymer films.     

Breath figure templated self-assembly of surface-acylated cellulose nanowhiskers confined as honeycomb films

Cellulose - The self-assembly of cellulose nanowhiskers (CNWs) in confined geometries provides a powerful method for the fabrication of novel structures. Herein, ordered honeycomb microporous films...     

溶剂散逸自组装制备导电各向异性的金属有序阵列

通过溶剂散逸自组装法制备了聚苯乙烯(PS)有序多孔膜. 利用水珠在冷的PS溶液表面凝结形成有序阵列, 使PS以水珠阵列为模板形成有序多孔膜. 将有序多孔膜的上层剥离并附着在可收缩性高分子表面, 并进行离子溅射, 除掉有序多孔膜后在可收缩膜上留下了有序的金属圆盘阵列. 经过收缩, 有序阵列不仅光学性质发生了改变, 而且实现了导电的各向异性.     

Synthesis of star-shaped polyhedral oligomeric silsesquioxane (POSS) fluorinated acrylates for hydrophobic honeycomb porous film application

Two different eight-arm star-shaped polyhedral oligomeric silsesquioxane (POSS) fluorinated acrylates were synthesized through atom transfer radical polymerization (ATRP) and applied for hydrophobic honeycomb-patterned porous films through the breath figure (BF) method. The structure of polymers was characterized by Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC), and surface analysis was featured by X-ray photoelectron spectroscopy (XPS). Depending on the influences of polymer architectures, solvents utilized, and solution concentrations, honeycomb-patterned porous films were obtained. It could be found that the introduction of fluorine components was a favorable condition for BF formation and chloroform (CHCl₃) utilized as solvent with an appropriate concentration of 30 mg/mL was the best condition for these hydrophobic honeycomb-patterned porous films. Meanwhile, the obtained honeycomb films could be retained after long-time preservation in an acid-base condition, which shows a great potential in filtration, cell culture, tissue engineering, and marine antifouling 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.     

Nanostructures and Functionalities in Polymer Thin Films

Several examples of self-organization in thin polymer films are considered for the fabrication of nanopatterned surfaces and nanoscopic objects. Mixed polymer brushes of statistical distribution at the surface, composed of two immiscible polymers covalently bonded to the substrate phase, segregate in the sub-micrometer scale. Interplay between lateral and perpendicular (sandwich-like) segregation effects switching behavior of the thin films upon exposure to different environments. The switching between brush morphologies is used for the fabrication of adaptive/responsive surfaces. Fabrication of nano-domains based on microphase segregation in block-copolymer systems is used for structures with lateral dimensions as small as 5-50 nm. The ordered copolymer structures are applied as templates for the fabrication of membranes, nanofibers and nanoparticles.     

Ordered micro/mesoporous composite prepared as thin films

A new synthesis method for preparation of thin films and powders consisting of zeolite beta nanocrystals embedded in ordered mesoporous silica matrix is described. The final structures possessing bimodal porosity, i.e., high degree of mesophase order and spatially defined microporous zeolite nanocrystals are obtained via simultaneous solvent evaporation of preformed silica/surfactant/ethanol/nanosized zeolite beta assemblies. The films were characterized with grazing-incident diffraction (GID), nitrogen sorption based on gravimetric measurements with quartz crystal microbalance (QCM) devices, and transmission electron microscopy (TEM). It is shown that the incorporation of beta nanocrystals in the mesoporous silica matrix and the mesophase order itself can be controlled through the variation of the fractional amounts of the zeolite nanoparticles and silica/surfactant solutions. The HR-TEM measurements showed that the nanosized Beta microporous crystals are separated and at the same time connected through an ordered mesostructured matrix.     

聚丁二烯有序多孔膜在热缩型聚乙烯膜上的收缩

采用溶剂散逸自组装制备了聚丁二烯(PB)有序多孔膜。水珠能在冷的高分子溶液表面凝结形成有序的阵列,溶剂蒸发后,高分子材料按照水珠排列的形貌形成了有序多孔膜。两性共聚物的加入能够起到稳定水滴的作用,从而确保多孔膜成为有序的结构。利用聚乙烯可收缩膜将聚丁二烯多孔膜收缩2次,得到长方形、梭形、条形和哑铃形的孔。孔的尺寸从微米级收缩至亚微米级,并对产生各种形状的机理进行了研究。     

Formation of ordered mesoporous films from in situ structure inversion of azo polymer colloidal arrays

This work shows that mesoporous polymeric films with spherical and elliptical pores can be obtained by in situ structure inversion of the azo polymer colloid arrays through selective interaction with solvent. The epoxy-based azo polymer contained both the pseudo-stilbene-type azo chromophores and the hydrophilic carboxyl groups. The colloidal spheres of the azo polymer were prepared by gradual hydrophobic aggregation of the polymeric chains in THF-H2O media, induced by a steady increase in the water content. Ordered 2D arrays of the hexagonally close-packed colloidal spheres were obtained by the vertical deposition method. After the solvent (THF) annealing, the ordered 2D arrays were directly transformed to mesoporous films through the sphere-pore inversion. Under the same condition, the 2D arrays composed of the ellipsoidal colloids, which were obtained by the irradiation of a polarized Ar+ laser beam on the colloidal sphere arrays, could be transformed to films with ordered elliptical pores. To our knowledge, this is the first example to demonstrate that mesoporous structures can be directly formed from the colloidal arrays of a homopolymer through structure inversion. This observation can shed new light on the nature of self-assembly processes and provide a feasible approach to fabricate mesoporous structures without the infiltration-removal step. By exploring the photoresponsive properties of the materials, mesoporous film with special pore structure and properties can be expected.     

Self-organization-induced three-dimensional honeycomb pattern in structure-controlled bulky methacrylate polymers: Synthesis, morphology, and mechanism of pore formation

Here we report, for the first time, a novel molecular design for three-dimensional honeycomb structures through a self-organization of hydrogen-bonded bulky anchoring group in a methacrylic polymer backbone. The polymerizable monomer design includes a methacrylic double bond linked to various hydrophobic anchoring units such as ethane, n-decane, tricyclodecane (TCD), and adamantane via a hydrogen-bonded cycloaliphatic urethane linkage. The structures of the polymers were confirmed by nuclear magnetic resonance (NMR) and the molecular weights of the polymer were determined by gel permeation chromatography (GPC). The methacrylate polymers having tricyclodecane and adamantane bulky anchoring groups self-organized to produce three-dimensional honeycomb patterns in tetrahydrofuran-water solvent mixture at ambient conditions, whereas its linear analogues (ethane, n-decane) failed to produce any micropattern. The scanning electron microscopy (SEM) analysis of the above-prepared polymer films revealed that the structure of the polymer played a major role in the formation of the honeycomb patterns. The solution Fourier transform infrared (FTIR) measurements confirmed that the bulky tricyclodecane and adamantane polymers have strong hydrogen-bonding interaction compared to that of their linear analogues, which is the driving force for the micropatterns. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) analysis of the bulky polymers revealed that the polymers exist as vesicles or micelles in the solution, which leads to the formation of the honeycomb pattern. The honeycomb pattern formation in the bulky polymer systems suggests that two cooperative factors such as hydrogen-bonding interaction and hydrophobicity of bulky anchoring units are necessary to induce three-dimensional honeycomb structures. To investigate the effect of molecular weights and its distribution on the self-organization process, both benzoyl peroxide (BPO) initiated free radical and atom transfer radical polymerization (ATRP) techniques were employed for the polymerization. Micropores formed irrespective of differences in molecular weight and polydispersity index (PDI); however, the pore size distribution was influenced by both molecular weights and PDI. Low molecular weight samples afforded polydisperse pores with the ATRP samples with more narrow PDI producing pores with large dimensions. The approach has also been investigated for polystyrene-bulky methacrylic copolymer, and the results revealed that uniform honeycomb patterns were produced for copolymers having more than 50 mol % incorporation of bulky units.     

Supercritical carbon dioxide processing of fluorinated surfactant templated mesoporous silica thin films

The effect of processing mesoporous silica thin films with supercritical CO2 immediately after casting is investigated, with a goal of using the penetration of CO2 molecules in the tails of fluorinated surfactant templates to tailor the final pore size. Well-ordered films with two-dimensional hexagonal close-packed pore structure are synthesized using a cationic fluorinated surfactant, 1-(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl)pyridinium chloride, as a templating agent. Hexagonal mesopore structures are obtained for both unprocessed films and after processing the cast films in CO2 at constant pressure (69-172 bar) and temperature (25-45 degrees C) for 72 h, followed by traditional heat treatment steps. X-ray diffraction and transmission electron microscopy analysis reveal significant increases in pore size for all CO2-treated thin films (final pore diameter up to 4.22 +/- 0.14 nm) relative to the unprocessed sample (final pore diameter of 2.21 +/- 0.20 nm) before surfactant extraction. Similar pore sizes are obtained with liquid and supercritical fluid treatments over the range of conditions tested. These results demonstrate that combining the tunable solvent strength of compressed and supercritical CO2 with the "CO2-philic" nature of fluorinated tails allows one to use CO2 processing to control the pore size in ordered mesoporous silica films.     

Recent advances in honeycomb-structured porous polymer films prepared via breath figures

Since its introduction in 1994, the preparation of ordered porous polymer films by the breath figure (BF) method has received a considerable interest. The so-called “honeycomb” (HC) films exhibit a hexagonal array of micrometric pores obtained by water droplet condensation during the fast solvent evaporation performed under a humid flow. The main focus of this feature article is to describe the recent advances in the design of honeycomb polymer films by the BF process. We first review the recent studies related to the honeycomb film formation through the exploration of different parameters such as the relative humidity, the polymer concentration, the drying rate, the substrate or the role of interfacial tension. The influence of the architecture and microstructure of the polymer is examined through examples. In this contribution, a special attention is given to the recent articles focused on the preparation of elaborate functional honeycomb-structured polymer films obtained via the simple BF method. In this context, we review the preparation of hierarchical HC films showing either sub- or super-structure, the formation of hybrid HC films by self-assembly of nanoparticles or in situ generation of the inorganic matter, the fluorescence in HC films introduced either by a fluorescent polymer or by fluorescent chemical groups, the elaboration of biomaterials from HC films decorated by glycopolymer and/or showing sensing ability and finally the design of functional polymeric surfaces with either stimuli-responsive or superhydrophobic properties.     

Self-organized polymer nanocomposite inverse opal films with combined optical properties

Inverse opal films with unique optical properties have potential as photonic crystal materials and have stimulated wide interest in recent years. Herein, iridescent hybrid polystyrene/nanoparticle macroporous films have been prepared by using the breath‐figure method. The honeycomb‐patterned thin films were prepared by casting gold nanoparticle‐doped polystyrene solutions in chloroform at high relative humidity. Highly ordered hexagonal arrays of monodisperse pores with an average diameter of 880 nm are obtained. To account for the observed features, a microscopic phase separation of gold nanoparticles is proposed to occur in the breath‐figure formation. That is, individual gold nanoparticles adsorb at the solution/water interface and effectively stabilize condensed water droplets on the solution surface in a hexagonal array. Alternatively, at high nanoparticle concentrations the combination of breath‐figure formation and nanoparticle phase separation leads to hierarchical structures with spherical aggregates under a honeycomb monolayer. The films show large features in both the visible and NIR regions that are attributed to a combination of nanoparticle and ordered‐array absorptions. Organic ligand‐stabilized CdSe/CdS quantum dots or Fe₃O₄ nanoparticles may be loaded into the honeycomb structure to further modify the films. These results demonstrate new methods for the fabrication and functionalization of inverse opal films with potential applications in photonic and microelectronic materials.     

界面上蜂窝状多孔薄膜的构建、性质和应用

综述了以Breath Figure(呼吸图案)法制备聚合物及纳米颗粒蜂窝状多孔结构的研究现状.当潮湿的气流吹到聚合物或纳米颗粒的有机溶液表面时,溶剂蒸发导致水微滴在液体表面冷凝重排成六角阵列结构.溶剂和水微滴蒸发完毕后,聚合物或纳米颗粒在基底上形成具有六角阵列的蜂窝状多孔结构.该技术是自组装领域的一大进展,在生物技术、组织工程、微图像技术、高端分离技术、光催化及医药等领域有望获得重要应用.本文系统阐述了规整蜂窝状孔结构材料的构建方法、构建材料、形成机理以及影响因素(包括湿度、浓度、气流方向和速度、溶剂、基底曲率等),评述了蜂窝状多孔薄膜的性质和应用,并对其在化学和材料科学领域的应用前景作了展望.