非共价键自组装有机功能材料

分子自组装对于某些化学反应过程、生物化学过程及生命活动的模拟等方面具有重要的意义。本文对非共价键组装方式自组装的有机功能材料的分类，结构、性质、自组装机理以及研究进展进行了综述。     

Functional block copolymers: nanostructured materials with emerging applications

Recent advances in polymer synthesis have significantly enhanced the ability to rationally design block copolymers with tailored functionality. The self-assembly of these macromolecules in the solid state or in solution allows the formation of nanostructured materials with a variety of properties and potential functions. This Review illustrates recent progress in the field of block copolymer materials by highlighting selected emerging applications.     

Polymerization-induced self-assembly of metallo-polyelectrolyte block copolymers

Cobaltocenium-containing polyelectrolyte block copolymer nanoparticles were prepared via polymerization-induced self-assembly (PISA) using aqueous dispersion RAFT polymerization. The cationic steric stabilizer was a macromolecular chain-transfer agent (macro-CTA) based on poly(2-cobaltocenium amidoethyl methacrylate chloride) (PCoAEMACl), and the core-forming block was poly(2-hydroxypropyl methacrylate) (PHPMA). Stable cationic spherical nanoparticles were formed in aqueous solution with low dispersity without adding any salts. The chain extension of macro-CTA with HPMA was efficient and fast. The effects of block copolymer compositions, solid content, charge density, and addition of salts were studied. It was found that the degree of polymerization of both the stabilizer PCoAEMACl and the core-forming PHPMA had a strong influence on the size of nanoparticles. © 2019 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 77–83     

Controlled synthesis of nanostructured silica-based materials from designed alkoxysilanes

Recent progress in the synthesis of nanostructured silica-based materials through the self-assembly process using well-designed alkoxysilane precursors is presented. Alkoxysilanes with covalently attached hydrophobic organic tails become amphiphilic when hydrolyzed to form silanol groups, leading to the formation of various mesostructures upon evaporation of solvents. The precursors having large oligosiloxane heads are particularly important because of their ability to form cylindrical assemblies, providing a direct pathway to ordered porous silica by removal of the organic groups. Our recent research includes (i) templated-synthesis of hierarchically ordered structures and (ii) design of molecules having chemically cleavable bonds to generate pores without calcination.     

Crystallization-driven self-assembly of semicrystalline block copolymers and end-functionalized polymers: A minireview

Self-assembly has been a powerful method to fabricate the polymer materials with well-defined structures and morphologies. Such assembled materials have shown wide potential applications in many fields such as nanomaterial, nanomedicine, lithography, and microelectronic. Crystallization has been a general behavior of stereoregular polymers. Besides the various noncovalent interactions, crystallization of polymer blocks or end groups can be an efficient way to manipulate the self-assembly pathway and assembled structures of polymers in both solid and solution. Crystallization-driven self-assembly has been widely implemented for the semicrystalline block copolymers (BCPs) and end-functionalized polymers. This minireview briefly presents the recent progresses in the crystallization-driven self-assembly of BCPs and end-functionalized polymers in both solid and solution states. Formation process, mechanism, and hierarchical structure of the crystallization-induced assemblies for BCPs and end-functionalized polymers are highlighted.     

Fabrication of cage-like particles via unstable seeded dispersion polymerization: A new concept in the polymerization-induced self-assembly

The formation mechanism of hollow micron-sized polystyrene (PS) particles having numerous dents on the surface, so-called cage-like particles, obtained from seeded dispersion polymerization (SDP) of 2-ethylhexyl methacrylate (EHMA) with low molecular weight (MW) PS particles stabilized by poly(vinyl alcohol) (PVA) in the presence of hexadecane droplets was investigated. It was found that association of poly(2-ethylhexyl methacrylate) (PEHMA)/hexadecane phases which occurs due to the instability of the obtained composite particles followed by a diffusion of PS ellipsoidal particles into each other is the main process responsible for the production of such unique morphology. Time course monitoring of the SDP showed that diffusion of hexadecane and/or PS and/or PEHMA phase into PS/PEHMA/hexadecane composite particles through PS shell which happens based on Ostwald ripening is the main phenomenon which results in the formation of the dents on the surface of final particles. Moreover, the experimental results revealed that in this reaction system, the polymerization develops in a faster manner rather than the SDP employing seed particles having higher MWs. Furthermore, it was observed that particles with different surface morphologies can be produced by using different hydrocarbons. The elimination of small particles which are produced in addition to the cage-like ones via decreasing the concentration of the stabilizer was another interesting finding of this research. The acquired results showed that unstable SDP is expected to be a new concept in polymerization-induced self-assembly (PISA) which employs instability of a dispersion for self-assembly of polymeric particles, and therefore, production of polymeric unique objects.     

Fabrication of polymeric nano-objects using PS5P2VP5 heteroarm star copolymers as building elements

This work is focused on the self-organization of an heteroarm star copolymer consisting of 5 polystyrene and 5 poly(2-vinylpyridine) (P2VP) arms emanated from a poly(divinyl benzene) core and the chemical stabilization of the resulting supramolecular nano-objects in the bulk and in solution. To tune various morphologies from the same star copolymer, selective and nonselective solvent media were used. Thepyridine moieties, forming distinct P2VP nanodomains in the copolymer nanostructures, were selectively crosslinked using 1,4-dibromobutane under mild conditions to yield stabilized polymeric “hairy” nano-objects, dispersible in hot tetrahydrofuran. The morphology of the resulting nanostructures was studied using scanning electron microscopy and was found to be strongly dependent on various factors, such as the self-assembly/casting conditions, the total time of the crosslinking reaction, and the dispersion procedure. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1636–1641, 2010     

聚合物纳米杂化材料的控制合成、自组装及功能化

聚合物纳米杂化材料的制备及功能化是当前国际前沿研究课题之一.特殊结构的聚合物可以通过分子间特殊相互作用,在纳米尺度上自发地组装成具有特殊结构和形态的集合体,这类材料在新材料、电子以及生物医学等领域具有广泛的应用前景.本文介绍国内外,特别是厦门大学在双亲性分子及嵌段共聚物的模板自组装、基于POSS单体纳米构筑单元以及POSS嵌段聚合物自组装的有机/无机纳米杂化材料、模板控制导电高分子材料纳米形态构筑等领域材料的可控合成和组装,与此同时对相关材料的性能及功能化应用进行了简要的讨论.     

基于大分子共组装法制备聚苯胺纳米粒子

首先,以丙烯酸(AA)、N-乙烯基吡咯烷酮(VP)和苯乙烯(St)为聚合单体,通过自由基共聚法合成了一种双亲无规共聚物P(AA-co-VP-co-St)。然后,在疏水作用和静电作用的共同诱导下,将该共聚物与聚苯胺(PANI)共组装形成形态可控且均匀分散的PANI纳米粒子。通过透射电子显微镜和激光动态光散射等研究了P(AA-co-VP-co-St)和PANI在水溶液中的共组装行为,并系统研究了亲水单体AA的物质的量分数对所制备的PANI纳米粒子粒径、形态的影响。结果表明:当AA物质的量分数为30%时,PANI纳米粒子的粒径最小。     

Silica-based mesoporous organic-inorganic hybrid materials

Mesoporous organic-inorganic hybrid materials, a new class of materials characterized by large specific surface areas and pore sizes between 2 and 15 nm, have been obtained through the coupling of inorganic and organic components by template synthesis. The incorporation of functionalities can be achieved in three ways: by subsequent attachment of organic components onto a pure silica matrix (grafting), by simultaneous reaction of condensable inorganic silica species and silylated organic compounds (co-condensation, one-pot synthesis), and by the use of bissilylated organic precursors that lead to periodic mesoporous organosilicas (PMOs). This Review gives an overview of the preparation, properties, and potential applications of these materials in the areas of catalysis, sorption, chromatography, and the construction of systems for controlled release of active compounds, as well as molecular switches, with the main focus being on PMOs.     

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.     

Dynamic Self‐Assembly of Gold/Polymer Nanocomposites: pH‐Encoded Switching between 1D Nanowires and 3D Nanosponges

The design of tunable dynamic self‐assembly of nanoparticles with switchable assembled dimensions and morphologies is a challenging goal whose realization is vital for the evolution of smart nanomaterials. Herein, we report on chitosan polymer as an effective supramolecular “glue” for aldehyde‐modified Au nanoparticles to reversibly modulate the states of self‐assembled nanocomposites. By simultaneous integration of dynamic covalent Schiff base interactions and noncovalent hydrogen bonds, the chitosan/Au nanocomposites could reversibly transform their assembled morphologies from one‐dimensional nanowires to three‐dimensional nanosponges in response to the variation of pH value. Moreover, the obtained nanosponges could be used as an efficient pH‐controlled cargo release system.     

A general method for the synthesis of nanostructured large-surface-area materials through the self-assembly of functionalized nanoparticles

A general synthetic method for the preparation of nanostructured materials with large surface area was developed by using nanoparticle building blocks. The preparation route involves the self-assembly of functionalized nanoparticles in a liquid-crystal phase. These nanoparticles are functionalized by using difunctional amino acid species to provide suitable interactions with the template. Optimum interactions for self-assembly of the nanoparticles in the liquid-crystal phase were achieved with one -NH2 group anchored to the nanoparticle surface per 25 A(2). To maximize the surface area of these materials, the wall thicknesses are adjusted so that they are composed of a monolayer of nanoparticles. To form such materials, numerous parameters have to be controlled such as the relative volume fraction of the nanoparticles and the template and size matching between the hydrophilic component of the copolymer and nanoparticles. The surface functionalization renders our synthetic route independent of the nanoparticles and allows us to prepare a variety of nanostructured composite materials that consist of a juxtaposition of different discrete oxide nanoparticles. Examples of such materials include CeO2, ZrO2, and CeO2-Al(OH)3 composites.     

呼吸图法制备聚亚甲基-b-聚甲基丙烯酸甲酯多孔薄膜

首先利用叶立德活性聚合和原子转移活性自由基聚合(ATRP)相结合制备了三个不同链段比的聚亚甲基-b-聚甲基丙烯酸甲酯(PM-b-PMMA)两嵌段聚合物. 接着以它们为原料, 利用静态呼吸图方法在四种不同溶剂中制备了一系列的具有蜂窝状表面的多孔薄膜, 用扫描电子显微镜(SEM)观察了多孔薄膜的形貌. 研究了溶剂、溶液浓度、聚合物链段长度及链段比等因素对多孔薄膜表面孔的大小和分布的影响. 结果表明: 当PM_2k-b-PMMA_2k嵌段聚合物浓度为3 wt%、溶剂为二硫化碳(CS₂)和二氯甲烷(CH₂Cl₂)时, 可以通过静态呼吸图方法制备出孔径为纳米级(520 nm)和微米级(1.1 μm)的较为规整的多孔薄膜. 多孔薄膜表面的孔径随PM-b-PMMA浓度的减小而增大|两嵌段聚合物中两个链段的长度及其链段比的变化对多孔膜表面孔径均产生较大的影响.     

Mechanically robust,ion-conductive,self-healing glassy hybrid materials via tailored Zn/imidazole interaction

Simultaneously achieving mechanical properties and rapid self-healing under ambient conditions is challenging because of slow diffusion dynamics. Here, we report the design of self-healing hybrids composed of low molecular mass multifunctional silsesquioxane nanoparticles with cross-linked networks formed from non-covalent metal–ligand interactions to address this challenge. Carefully tuning the bond dynamics and strength by changing the counterions and metal–ligand feed ratio enables rapid self-healing and robust mechanical properties (tensile strength = 14.9 MPa and elongation at break = 4.36%) with ion conductivity. Static tensile behavior and rheological response of hybrids revealed dynamic interactions. The hybrids without entanglement can heal from a physical cut at room temperature with a healing efficiency of approximately 90%. This molecular design strategy provides a versatile pathway for the production of self-healing hybrid materials with excellent mechanical properties.     

Preparation and antibacterial activity of hybrid materials containing quaternary ammonium salts via sol-gel process

Organic-inorganic hybrid coatings containing quaternary ammonium salts (QAS) bonded to the organic-inorganic network were prepared from tetraethoxysilane and triethoxysilane terminated poly(ethylene glycol)-block-poly(ethylene) using a sol-gel process. They were applied as a thin layer (0.6-1 μm) to PE films and the antibacterial activity of the coated films was tested against both Gram-negative (Escherichia coli ATCC 25922) and Gram-positive (Staphylococcus aureus ATCC 6538) bacteria. Measurements at different contact times showed a rapid decrease of the viable count for both the tested strains. In particular, after 48 h of contact, a decrease of 96.4% and 99.1% of E. coli and S. aureus, respectively, was observed. The permanence of the antibacterial activity of the coated films was demonstrated through repeated washings and prolonged immersion in physiological saline solutions at 37 °C. Indeed, due to the removal of QAS moieties by the nucleophilic attack of water, the antibacterial activity after 24 h was strongly reduced when measured on samples submitted to several washings. However, a quite good antibacterial activity was observed even on the same samples after 96 h, probably due to a spontaneous partial restoring of the QAS on the surface. Very good transparency, quite good adhesion and high wettability are further features of these hybrid coatings.     

The supramolecular chemistry of organic-inorganic hybrid materials

The combination of nanomaterials as solid supports and supramolecular concepts has led to the development of hybrid materials with improved functionalities. These "hetero-supramolecular" ideas provide a means of bridging the gap between molecular chemistry, materials sciences, and nanotechnology. In recent years, relevant examples have been reported on functional aspects, such as enhanced recognition and sensing by using molecules on preorganized surfaces, the reversible building of nanometer-sized networks and 3D architectures, as well as biomimetic and gated chemistry in hybrid nanomaterials for the development of advanced functional protocols in three-dimensional frameworks. This approach allows the fine-tuning of the properties of nanomaterials and offers new perspectives for the application of supramolecular concepts.