光固化涂料的应用和市场前景

光固化涂料主要由低聚物、单体、光引发剂及助剂组成。UV固化的主要反应历程是由辐射引起光引发剂分解,生成活性自由基引发单体以氐聚物聚合交联。针对光固化涂料的性能特点和光固原理,介绍了光固化涂料的应用领域,阐述了光固化涂料适合多种基材的涂装,研究了光固化涂料在汽车装饰上的应用,指出了光固化涂料的发展前景与潜力。     

The effect of polycations on early cement paste

This paper studies the possibility for improving the ductility of cement based materials by means of oligocationic additives. Actually, the setting of cement is due to ionic correlation forces between highly negatively charged C-S-H nanoparticles throughout a calcium rich solution. The main drawback of this strong attraction is its very short range that results in low elastic deformation of hydrated cementitious materials. A way to enlarge the attraction range between C-S-H particles would be to add cationic oligomers that would compete with calcium ions modifying the ionic correlation forces via a bridging mechanism of longer range, which could lead to a more ductile material. The studied parameters were the polymerization degree, the separation distance between the charged monomers and the balance between oligocations and monovalent and divalent cations in the solution. The results, both experimental and numerical by Monte Carlo (MC) simulations, demonstrate that cationic oligomers can compete with calcium cations as counterions to the C-S-H surface. The cohesive forces between C-S-H surfaces, calculated by MC simulations, show an interesting behaviour where range and magnitude can be tuned with oligomer concentration, polymerization degree and line charge density. Thus, it seems possible to modulate the ductility and critical strain of cement by addition of cationic oligomers.     

Double Dianhydride Backbone Polyimide Aerogels with Enhanced Thermal Insulation for High‐Temperature Applications

Aerogels owe their high thermal insulation and other unique properties to their nanostructure configuration. However, controlling the aerogels' morphology is always a scientific challenge. In this study, double dianhydride backbone (double backbone) polyimide aerogels with tailored nanostructure assembly are created for the first time. This is achieved by controlled polymerization reaction of oligomers with distinct dianhydride monomers. Combining the two oligomers through a controlled polymerization reaction is a successful strategy for tailoring the aerogels nanostructure assembly as well as other properties. The fabricated double backbone aerogel presents 40% reduced thermal conductivity of 19.7 mW mK^?1 over previously studied polyimide aerogels along with the compression modulus of 1.64 MPa at a relatively low density of 0.068 g cm^?3. Such low thermal conductivity is comparable with the inorganic counterparts. Light in weight and high thermally insulated polyimide aerogels with suitable mechanical properties and high service temperature are an appropriate replacement for current fireproof insulation materials.     

Study of cationic ring‐opening photopolymerizations using optical pyrometry

Studies of the photoinitiated cationic ring‐opening polymerizations of epoxide and oxetane monomers were conducted using optical pyrometry. Using this technique, the temperature of these photopolymerizations was monitored as a function of time. The effects of photoinitiator type and monomer structure on the rates of photopolymerization were investigated. Optical pyrometry was also used to investigate the acceleration of the photopolymerizations of various epoxide and oxetane monomers. Certain mixtures of monomers displayed synergistic effects that markedly increased their overall rates of polymerizations. In all cases in which acceleration of polymerization rate was noted, it could be attributed to an increase in the speed of ring opening of the initially formed protonated cyclic ether. The effects of relative humidity on the rate of cationic ring‐opening photopolymerizations of cyclic ether monomers were also investigated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3303–3319, 2004     

Oil-in-oil emulsions: a unique tool for the formation of polymer nanoparticles

Polymer latex particles are nanofunctional materials with widespread applications including electronics, pharmaceuticals, photonics, cosmetics, and coatings. These materials are typically prepared using waterborne heterogeneous systems such as emulsion, miniemulsion, and suspension polymerization. However, all of these processes are limited to water-stable catalysts and monomers mainly polymerizable via radical polymerization. In this Account, we describe a method to overcome this limitation: nonaqueous emulsions can serve as a versatile tool for the synthesis of new types of polymer nanoparticles. To form these emulsions, we first needed to find two nonmiscible nonpolar/polar aprotic organic solvents. We used solvent mixtures of either DMF or acetonitrile in alkanes and carefully designed amphiphilic block and statistical copolymers, such as polyisoprene- b-poly(methyl methacrylate) (PI- b-PMMA), as additives to stabilize these emulsions. Unlike aqueous emulsions, these new emulsion systems allowed the use of water-sensitive monomers and catalysts. Although polyaddition and polycondensation reactions usually lead to a large number of side products and only to oligomers in the aqueous phase, these new conditions resulted in high-molecular-weight, defect-free polymers. Furthermore, conducting nanoparticles were produced by the iron(III)-induced synthesis of poly(ethylenedioxythiophene) (PEDOT) in an emulsion of acetonitrile in cyclohexane. Because metallocenes are sensitive to nitrile and carbonyl groups, the acetonitrile and DMF emulsions were not suitable for carrying out metallocene-catalyzed olefin polymerization. Instead, we developed a second system, which consists of alkanes dispersed in perfluoroalkanes. In this case, we designed a new amphipolar polymeric emulsifier with fluorous and aliphatic side chains to stabilize the emulsions. Such heterogeneous mixtures facilitated the catalytic polymerization of ethylene or propylene to give spherical nanoparticles of high molecular weight polyolefins. These nonaqueous systems also allow for the combination of different polymerization techniques to obtain complex architectures such as core-shell structures. Previously, such structures primarily used vinylic monomers, which greatly limited the number of polymer combinations. We have demonstrated how nonaqueous emulsions allow the use of a broad variety of hydrolyzable monomers and sensitive catalysts to yield polyester, polyurethane, polyamide, conducting polymers, and polyolefin latex particles in one step under ambient reaction conditions. This nonpolar emulsion strategy dramatically increases the chemical palette of polymers that can form nanoparticles via emulsion polymerization.     

Mechanical Properties of the Modified Denture Base Materials and Polymerization Methods: A Systematic Review

Amidst growing technological advancements, newer denture base materials and polymerization methods have been introduced. During fabrication, certain mechanical properties are vital for the clinical longevity of the denture base. This systematic review aimed to explore the effect of newer denture base materials and/or polymerization methods on the mechanical properties of the denture base. An electronic database search of English peer-reviewed published papers was conducted using related keywords from 1 January 2011, up until 31 December 2021. This systematic review was based on guidelines proposed by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The search identified 579 papers. However, the inclusion criteria recognized 22 papers for eligibility. The risk of bias was moderate in all studies except in two where it was observed as low. Heat cure polymethyl methacrylate (PMMA) and compression moulding using a water bath is still a widely used base material and polymerization technique, respectively. However, chemically modified PMMA using monomers, oligomers, copolymers and cross-linking agents may have a promising result. Although chemically modified PMMA resin might enhance the mechanical properties of denture base material, no clear inferences can be drawn about the superiority of any polymerization method other than the conventional compression moulding technique.     

A new class of silicone resins for coatings

A new class of silicone has been developed for coatings or as coating additives. Cycloaliphatic silane monomers were prepared and reacted into more easily handled cyclic oligomers. These cyclic oligomers were ring-opened into siloxane polymers. The polymers were functionalized with a variety of groups, including: amino, glycidyl epoxide, cyclohexene epoxide, acrylic, and alkoxysilane. The cycloaliphatic silicones have been designed for a number of different curing conditions: (1) ambient temperature-cure (amino and glycidyl epoxide), (2) cationic ultraviolet (UV)-cure (cyclohexene epoxide), (3) radical UV-cure (acrylic), and (4) moisture-cure (alkoxysilane). The end usages thus far have been focused on silicone coatings; however, usage as coating additives will be a focus for future research. The cycloaliphatic silicone has been UV-cured with mixed sol–gel precursors for usage as aerospace coatings. The cycloaliphatic silicones have also been ambient temperature-cured for release coatings, and have application as anti-fouling coatings. The inherent low surface energy makes the cycloaliphatic silicones prime candidates for surface tension additives. Presented at the 2006 FutureCoat! Conference, sponsored by the Federation of Societies for Coatings Technology, in New Orleans, LA, on November 1–3, 2006.     

Metal Chelate Monomers as Precursors of Polymeric Materials

The principal advances and problems of the preparation of polymeric materials based on metal chelate monomers containing metal chelate cycle and functionality are analysed. The data are systematized according to methods for preparing polymeric materials: homopolymerization, copolymerization, living and controlled polymerization, grafting polymerization, electropolymerization, polycondensation, as well as synthesis of dendrimers and hyperbranched polymers based on metal chelate monomers. Special attention is paid to the effect of a metal on both the synthesis mechanism and properties of the products formed. The principal applications of polymeric materials based on metal chelate monomers are considered.     

乳化环氧改性的丙烯酸系乳液室温固化体系

将乙二醇二缩水甘油醚分散在水中制成环氧化合物乳液,并以其为交联剂,用以对丙烯酸系单体/胺基单体乳液共聚物的改性,制成了双组分室温固化乳液涂料。研究了乳化剂种类和胺基单体用量对聚合稳定性的影响,结果表明,若采用p 壬基酚聚氧化乙烯醚硫酸钠为乳化剂,且胺基单体用量低于单体总量2 5%时,可以制得稳定的带胺基的共聚物乳液。将丙烯酸系共聚物乳液和环氧乳液复合并在室温下干燥成膜,通过对聚合物膜的DSC和力学性能测试均表明,双组分体系在成膜过程中发生了交朕反应,而未加环氧化合物的单组分聚合物乳液成膜时则不发生交联。     

UV固化材料进展

由于UV固化技术固有的特点使其在近几年各个领域都获得了高速的发展,但所占市场份额仍然很小。经过学术界和各大公司的努力,目前已经在UV固化材料方面取得了可喜的成绩。稀释单体、预聚体在数量和质量上都有大幅度增加,发展方向是降低刺激性、低毒和赋予特殊功能:在双光子引发自由基聚合、阳离子光固化、杂混光固化、光产碱催化聚合、无光引发剂光固化、水基固化方面取得了一定的进展;UV粉末涂料克服了传统粉末涂料的缺点脱颖而出,成为近年来研究开发的热点;UV固化纳米材料更是集纳米技术、纳米材料、UV固化技术于一体,预计将会开发出具有特殊功能的新材料;UV固化技术在电子、信息领域也具有很好的发展前景。     

Surface textures induced by convection in thin films of polymeric and polymerizable fluids

Thin liquid layers of polymer solutions, oligomers and monomers, and oligomer–monomer bilayers were used as model systems to explore the mechanism of formation of surface textures in solid coatings and films. It was shown that under particular conditions vertical temperature gradients imposed on these fluid layers induce in them various types of convection. We demonstrated that hexagonal patterns with a high degree of order and symmetry are generated in fluid films undergoing surface tension-driven convection. Various non-equilibrium textures have been trapped in the solid state either by vitrification induced by solvent evaporation from the fluid layer, or by carefully performed polymerization of monomers and oligomers. Finally, we demonstrated that convection patterns can be replicated in convection-passive fluids by bringing them in contact with a fluid layer undergoing convection.     

Novel crosslinking system with hydroxyl-containing polymer, alicyclic polyepoxide and polyalkoxysilane

The crosslinking system based on the reaction among alicyclic epoxide group, hydroxyl group and alkoxysilyl group in the presence of aluminum β-diketone chelate have been developed. Five kinds of reaction are possible, and the result of gas chromatography and infrared analyses indicated that the main reaction is the ring-opening reaction of alicyclic epoxide group with hydroxyl group and/or hydroxysilyl group. The acrylic resin obtained by free radical polymerization of these three kinds of functional monomers and non-functional monomers showed good curing property, and the film was superior in acid rain resistance and outdoor durability. The resin is suitable to use in automotive 2coat–1bake clear coat. The viscosity of this binder system was remarkably reduced by addition of a low molecular weight alicyclic polyepoxide compound and an alkoxysilane oligomer without affecting to its good curing property. Such a system made it possible to design novel high solid coatings. It was found that the crosslinking could be extended to the combination of a polyester polyol, an alicyclic epoxide compound and an alkoxysilane oligomer. In this case, it was necessary that the polyester polyol contained highly reactive terminal hydroxyl group in the branch chains.     

Photopolymerization of carbazolyloxiranes

Photopolymerizations of 1-allyloxy-3-(carbazol-9-yl)-2-propanol glycidyl ether and 1-(carbazol-9-yl)-4-oxa-2-pentanol glycidyl ether with diaryliodonium salts in solution and in bulk are reported. These reactions give oligomers of degree of polymerization 4–6. The influence of the functional groups of the monomers on the rate of polymerization, conversion limit and molecular weight is discussed. The effects of photoinitiator and reaction media on these factors have also been studied.     

Synthesis of methyl methacrylate oligomers with substituted tetraphenylethane initiator

The radical polymerization of (meth)acrylic monomers (eg methyl methacrylate; MMA) with benzopinacolate‐type initiators has been investigated mainly by Bledzki and Braun. With respect to this work, the typical system (MMA/1,1,2,2‐tetraphenyl‐1,2‐bis(trimethylsiloxy)ethane) has been investigated. The concomitant uses of ¹H NMR and size exclusion chromatography have allowed the percentage of MMA telechelic oligomers present in the medium versus reaction time to be followed. The results show clearly a decrease in the living character of this type of radical polymerization with evolution from telechelic oligomers to monofunctional polymers. In addition, the polymerization features versus reaction time are simulated using the GEAR package; good agreement between the calculated and experimental data is obtained. © 2001 Society of Chemical Industry     

来自塑料包材的化妆品安全性隐患

塑料内常含有残留单体、添加剂、低聚体、加工助剂等化学物,在其与产品接触过程中可能发生迁移而污染产品,从而对人体健康产生潜在的危害。介绍了来自塑料包装材料的存在安全隐患的迁移物及其危害,讨论了迁移的理论基础以及迁移过程的预测模型。指出了对包装材料安全监管和深入研究的必要性、监管和进一步研究的重点方向,以及化妆品生产企业确定包装材料时应该关注的重点。     

Photopolymerization of acryl composites for producing waveguides with high transparency within telecommunication spectral regions

The photopolymerization of hydrocarbon and fluorine-containing monomers and oligomers synthesized in this work for the creation of planar polymer waveguides has been studied. The kinetics of the copolymerization of hydrocarbon and fluorinated compounds hardly depends on the number and structure of fluorinated moieties. The overall kinetics of the photoinitiated polymerization of acryl oligomers with different chemical nature of their oligomer block, molecular masses, and local and macroscopic viscosities has been studied by IR spectroscopy. At high initiation rates, the oligomer block’s flexibility, which is governed by the number of groups with a low potential rotational barrier, e.g., carbonate groups, is the principal factor that influences the kinetics of polymerization. At low initiation rates, the viscosity of oligomers becomes an essential factor. The optimal conditions for molding optical articles from hydrocarbon and fluorinated acryl oligomer composites have been determined.     

Volume shrinkage of UV-curable coating formulation investigated by real-time laser reflection method

Volume shrinkage is one of the main drawbacks of UV-cured coatings and can lead to premature coating failures. Due to the rapid polymerization during UV-curing, real-time volume shrinkage has been challenging to measure accurately. In this article, the shrinkage process of UV-curable formulations was systematically investigated by a recently developed laser reflection method. The influence of oligomers, monomers, and photoinitiators on shrinkage process has been evaluated. Compared with the oligomers, the monomer was the main contributor to shrinkage due to the high concentration of double bonds. Polymerization shrinkage could be reduced by increasing the oligomer/monomer ratio. Because monomers were the main contributors of shrinkage, the chemical structure of monomers was important for decreasing shrinkage. Methacrylate monomers decreased the final shrinkage but unfortunately reduced the conversion. Monomers with a high degree of ethoxylation lowered the shrinkage and simultaneously increased the conversion. The concentration of photoinitiators had no obvious effect on the normalized shrinkage. Thus, the low shrinkage caused by the low concentration of photoinitiators was only attributed to the significant drop of the conversion.     

纤维素自组装材料的研究进展

纤维素自组装材料具有可再生、生物相容性好、可生物降解且力学性能高的优点,是最有潜力的绿色材料之一。纤维素及其衍生物可直接与第二组装单体构筑纤维素自组装材料,也可利用化学修饰研究改性后的纤维素及衍生物的自组装行为,其中改性处理是最主要的构筑方式。本文着重介绍了纤维素及纤维素衍生物的改性与自组装,对比分析了长碳链疏水化、乙烯基类单体原子转移自由基聚合、脂肪族聚酯单体开环聚合、氨基酸单体可逆-加成断裂链转移聚合改性合成组装分子的原理与特点,综述了组装分子在水体系和非水体系中构筑纤维素自组装材料的最新研究状况,指出纤维素及纤维素衍生物改性后构筑的组装材料具有智能响应性,可通过外界环境变化（如温度、pH、CO₂等）调节纤维素自组装形态,在药物控释、生物传感器及生物膜材料方面有潜在的应用价值;最后对纤维素自组装材料的可增长点进行了展望。