Polymer Sol-Gel Synthesis of Hybrid Nanocomposites

The current state and main problems of polymer sol-gel synthesis as a method of the preparation of hybrid polymer-inorganic nanocomposites are analyzed. The general characterization of sol-gel reactions is given and the routes of the combination of sol-gel synthesis with the polymerization of traditional monomers are considered. Particular attention is given to the formation of sol-gel precursors in the presence of organic polymers, including the formation of interpenetrating hybrid networks. The specificity of hybrid nanocomposites based on multicomponent ceramics is discussed. The sol-gel process is analyzed as a promising route for the preparation of bioceramics in the presence of templates.     

Recent advances in the synthesis and applications of azo initiators

This mini-review describes recent developments and trends in the area of syntheses and applications of azo compounds, which are planned to act as initiators of radical reactions, particularly polymerizations. The paper reports chemical modifications of well-known initiators (AIBN, etc.) or variants of syntheses of new types of these compounds. The chemical modifications of basic skeletons of azo initiators are discussed in the context with their properties and applications. Also discussed are the contemporary trends in the development of these initiators, particularly in preparation of microparticles and nanoparticles of polymers or hybrid inorganic–organic microparticles and nanoparticles prepared for intentional studies and applications.     

Dendrimers and hyperbranched polymers as high-loading supports for organic synthesis

Polymeric supports have become a big necessity for automated synthesis and combinatorial chemistry, yet, the loading capacities of most polystyrene resins are very limited (typically < 1.5 mmol x g(-1)). Dendrimers and hyperbranched polymers have been discussed for this application and now became readily available. These soluble polymers can either be used directly as high-loading supports for substrates, reagents, and catalysts or alternatively in hybrid polymers linked to conventional polystyrene resins.     

Horseradish peroxidase‐based hybrid nanoflowers with enhanced catalytical activities for polymerization reactions of phenol derivatives

Catalytic activity and stability of HRP‐Cu²⁺ hybrid nanoflowers (hCu‐NFs) in the polymerization reactions of phenol derivatives was investigated. It was observed that the catalytic activity and stability of hybrid nanoflowers on the polymerization of the phenol derivatives was considerably higher compared to free Horseradish peroxidase (HRP) enzyme. The hCu‐NFs effectively polymerized phenolic compounds as a novel nanobiocatalyst and led to polymers having quite high yields, molecular weights, and thermal stabilities compared to free HRP enzyme. The hCu‐NFs provide substantial repeated use and showed some degree of catalytic activity even after fourth cycle experiment in the polymerization reactions.     

Progress in controlled polymerization and design of novel polymer architectures

Recent developments of new synthetic methods are stimulating the design of new polymers. Modern generations of highly active and selective transition metal catalysts give excellent control on molecular weight, regio- and stereoregularities, long- and short-chain-branching, polymer crystallization, and morphology of olefin, diene, cyclolefin, and styrene polymers. Ethene is copolymerized with polar comonomers such as carbon monoxide and acrylates in new low pressure processes. Catalytic coupling reactions of aromatic halogen compounds and bisphenols afford rigid polyarylenes. „Living” radical polymerization (“TEMPO” and “ATRP”) produce a wide range of telechelics, block copolymers and cascade macromolecules. In reactive processing oxazoline-mediated coupling reactions are the key to melt diversification of well-known polymers. Supramolecular concepts are being applied to tailor hybrid polymers and nanocomposites. Precision in polymer synthesis is the key to new materials with wide application range.     

Cyclic polymers: past,present and future

Methods for characterising cyclic polymers are illustrated by reference first to dilute solution methods for cyclic poly(dimethylsiloxane) (PDMS) and then to the entrapment of cyclic polymers in networks. Preparative routes to cyclic polymers are then reviewed, including ring-chain equilibration reactions, coupling and condensation reactions and new methods using polymer-supported reagents. Some of the properties of cyclic PDMS are discussed, including differences between ring and chain polymer properties such as their melt viscosities and glass transition temperatures. Methods for preparing the first polymeric catenanes are described, using polymer-supported reagents. Future directions for cyclic polymer chemistry are indicated, including topological polymer chemistry.     

含倍半硅氧烷的杂化聚合物

从杂化材料的形成方式 ,说明含倍半硅氧烷类杂化材料是基于化学键合作用形成的分子内杂化体系 ,是一类新型高性能的有机_无机杂化材料。介绍了倍半硅氧烷的结构、合成方法及性能特点 ,重点阐述了多面齐聚倍半硅氧烷类杂化聚合物的性能特点及其发展趋势。     

Use of Molecular Imprinted Polymers for the Separation and Preconcentration of Organic Compounds

Data on the use of molecular imprinted polymers for the separation and preconcentration of organic substances in chemical analysis are summarized. The main approaches and methods used in the synthesis of these polymers are considered. The development of combined and hybrid methods of analysis with the use of these adsorbents is discussed.     

Metal-Catalyzed Coupling Reactions In The Synthesis Of New Conducting Polymers

The use of transition metal-catalyzed coupling reactions in the synthesis of conducting polymers is discussed. These reactions are of growing importance in polymer synthesis and are particularly important in the synthesis of highly functionalized conjugated (conducting) polymers. In this report we discuss applications of this methodology for the synthesis of conducting polymer sensory materials and polymers with reactive functional groups. In the sensory polymers we have incorporated crown ether groups which induce perturbations to the polymer's electronic structure when exposed to an alkali metal ion. Our interest in polymers with reactive functional groups is for the development of polymers which can be transformed into novel all-carbon ladder polymers.     

主链掺杂氧原子聚硅烷的研究进展

介绍了一类新型有机硅聚合物主链掺杂氧原子聚硅烷的合成与性质.该类聚合物是通过氧原子有规律地插入聚硅烷主链,形成具有氧杂低聚硅烷的序列结构(-[(SiMe2)mO]n-).聚合物的主链呈现了聚硅烷以及聚硅氧烷的杂化体结构.通过对此类聚合物性质的研究,能够获得有关此类聚合物行为的知识,从而进一步促进人们对聚硅烷和聚硅氧烷化学性质的了解.总结了此类聚合物的两类有效合成方法:通过α,ω-二功能基封端的线性硅烷低聚体缩聚反应法以及氧杂环硅烷单体的开环聚合反应法,包括氧杂环硅烷单体的开环聚合平衡和反应机理.讨论了此类聚合物的表征、热稳定性及其结构形态.在结论部分展望了此类聚合物的预期应用前景.     

Synthesis and characterization of novel poly(arylene ether)s containing 1,3,4-oxadiazole units

Starting from some new 2,5-disubstituted-1,3,4-oxadiazole difluorides, synthesized by cyclocondensation of dihydrazides with 4-fluorobenzoic acid, novel poly(arylene ether)s were prepared by halo displacement polymerizations with bisphenol A in the presence of potassium carbonate. Model reactions demonstrated the unsuitableness for halo displacement reactions of the difluoride containing the SO₂ group. The synthesis and characterization of polymers are discussed and the thermal properties are compared with those of other polymers reported in literature.     

Supramolecular Peptide/Polymer Hybrid Hydrogels for Biomedical Applications

Peptides and polymers are the “elite” building blocks in hydrogel fabrication where the typical approach consists of coupling specific peptide sequences (cell adhesive and/or enzymatically cleavable) to polymer chains aiming to obtain controlled cell responses (adhesion, migration, differentiation). However, the use of polymers and peptides as structural components for fabricating supramolecular hydrogels is less well established. Here, the literature on the design of peptide/polymer systems for self‐assembly into hybrid hydrogels, as either peptide‐polymer conjugates or combining both components individually, is reviewed. The properties (stiffness, mesh structure, responsiveness, and biocompatibility) of the hydrogels are then discussed from the viewpoint of their potential biomedical applications.     

Recent advances in the preparation of hybrid nanoparticles in miniemulsions

In this review, we summarize recent advances in the synthesis of hybrid nanoparticles in miniemulsions since 2009. These hybrid nanoparticles include organic–inorganic, polymeric, and natural macromolecule/synthetic polymer hybrid nanoparticles. They may be prepared through encapsulation of inorganic components or natural macromolecules by miniemulsion (co)polymerization, simultaneous polymerization of vinyl monomers and vinyl-containing inorganic precursors, precipitation of preformed polymers in the presence of inorganic constituents through solvent displacement techniques, and grafting polymerization onto, from or through natural macromolecules. Characterization, properties, and applications of hybrid nanoparticles are also discussed.     

Synthesis and electrical conductivity of poly(arylene vinylene). I. Poly(2,5-dimethoxyphenylene vinylene) and poly(2,5-dimethylphenylene vinylene)

The highly conjugated aromatic polymers, poly(2,5-dimethoxyphenylene vinylene) and poly(2,5-dimethylphenylene vinylene), were obtained from their water soluble, sulfonium salt precursor polymers. Films of these polymers were reacted with either AsF₅ or I₂ vapor. Poly(2,5-dimethoxyphenylene vinylene) showed increases in electrical conductivity of up to 14 to 15 orders of magnitude for these two dopants, while an 8 to 9 order of magnitude increase was observed for poly(2,5-dimethylphenylene vinylene) with the same dopants. The synthesis of the precursor polymers, the properties and elimination reactions of films of the precursors, the doping reactions, and the conductivities of the resulting phenylene vinylene films are discussed.     

Synthesis of New Functional Silicon-Based Condensation Polymers

A new class of photosensitive aromatic polymers containing disilane units was successfully synthesized from new disilane-based monomers such as 1,2-bis(diethylamino)tetramethyldisilane and 1,2-bis(p-aminophenyl)tetrarnethyldisilane. The disilane-contain-ing aramids and polyimides had glass transition temperatures above 190°C, and all the polymers were thermally stable up to 300°C in air. The polymers were photosensitive; their molecular weight decreased rapidly upon ultraviolet light irradiation. The photosensitive polymers, especially the soluble polyimides having diphenyl sulfone units, were potential candidates for positive working photoresist materials. New highly branched polysiloxane star-burst polymers were synthesized by a siloxane synthetic reaction starting from tris[(phenyldimethylsiloxy)dimethylsiloxy]methylsilane and bis[(phenyldimethylsiloxy)methylsiloxy]dimethylsilanol as the initial core (G0-Ph) and the building block, respectively. Thus, the first generation polymer G1-Ph, second generation polymer G2-Ph, and third generation polymer G3-Ph had 6, 12, and 24 phenylsilyl groups in their exterior layers. The formation of the siloxane-based starburst polymers were confirmed by means of ¹H-, ¹³C-, and ²⁹Si-NMR spectroscopy. These polysiloxane starburst polymers were suggested to have spherical structure. Some functionalized starburst polymers were further synthesized by the introduction of functional groups in their exterior layers. New silica-polyimide hybrid materials were prepared by the sol-gel process through the hydrolysis-condensation reactions of tetraethoxysilane in the presence of the polyamic acid (polyimide precursor) in dimethylacetamide, followed by heating at 270°C. The hybrid system having silica content up to 70 wt% had good quality films. The spherical silica particles were dispersed homogeneously in the polyimide matrix. With increasing silica content, the glass transition temperature and decomposition temperature, as well as the modulus of the hybrid films, increased, while the coefficient of thermal expansion decreased.     

新型无机聚合物的设计合成、结构规律与性能研究*

本文以新型无机聚合物的合理合成和物理性能研究为主线, 总结3个系列具有新颖结构聚合物的组装与结构化学规律: (1)通过化学自组装法设计合成出系列金属-有机纳米笼、金属-有机纳米管和金属-有机纳米线.研究了合成金属-有机纳米分子的规律,开辟了一条合成金属-有机纳米分子的新途经.(2)通过结构调控、金属与桥联基元作用,把团簇单元活化后合成一维新型无机聚合物.在研究反应机理过程中分离和表征了大量的中间态产物,从而得到了这类聚合物合理合成的规律.(3)设计合成出二维层状(石墨型)、三维大孔(分子筛型)、金属聚硫及稀土与过渡金属混合4个系列新型的无机聚合物,总结了它们的结构规律和反应规律.在制备合成中既有结构单元自组装的反应又有设计合成的方法.通过系列化合物的结构表征和光、电或磁性能的研究, 探索出系列聚合物具有半导体性能和非线性光学性能,总结出聚合物的结构规律与基本结构单元组装的关系以及结构与性能的关系.     

Synthesis of new polyimides by Diels–Alder reaction of bis(2-pyrone)s with bismaleimides

The reaction of various substituted bis(2-pyrone)s with bismaleimides in dilute solution was carried out to produce linear soluble polymers with coronand structure. The number-average molecular weights of the polymers ranged from 7000 to 18,000 (vapor pressure osmometry). Polymer structures were identified by NMR spectroscopy and model reactions. The stereochemistry and the mechanism are discussed. © 1995 John Wiley & Sons, Inc.     

Methods for the synthesis of uniform polymers

The difficulties encountered in the preparation of polymers that are uniform chemically, structurally, and in their molecular weight are due mainly to the wide variety of possible polymers. This arcticle gives a review of attempts to synthesize homogeneous polymers by chain reactions and by stepwise synthesis. Syntheses on templates are extremely important in living cells; methods have recently been found for syntheses of this type that are independent of natural processes. Uniform polymers can also be obtained by reactions on existing polymers. In replicating polymers, this in principle requires the modification of only one polymer molecule.     

Functional porous organic polymers for heterogeneous catalysis

Porous organic polymers (POPs), a class of highly crosslinked amorphous polymers possessing nano-pores, have recently emerged as a versatile platform for the deployment of catalysts. The bottom-up approach for porous organic polymer synthesis provides the opportunity for the design of polymer frameworks with various functionalities, for their use as catalysts or ligands. This tutorial review focuses on the framework structures and functionalities of catalytic POPs. Their structural design, functional framework synthesis and catalytic reactions are discussed along with some of the challenges.     

由聚合物门控的介孔二氧化硅基刺激响应性药物递送系统

本文主要介绍了以聚合物体系作为门控构筑的基于介孔二氧化硅纳米粒子的刺激响应性药物控释体系,并根据聚合物类别将门控体系分为聚合物刷、聚合物交联网络和聚合物包裹层三类.根据聚合物"阀门"与无机纳米粒子的共价或非共价连接方式,综述了这些杂化材料在不同外界刺激作用下的药物控制释放行为,并给出该领域所面临的机遇和挑战.