星形聚合物微凝胶的合成及其研究进展

星形微凝胶是1种具有特殊结构的聚合物微凝胶,具有广阔的应用前景。活性聚合(如阴离子活性聚合、阳离子活性聚合、氮氧稳定自由基聚合及原子转移自由基聚合(ATRP))是星形微凝胶合成的最常用且最有效的方法。对该方法在星形微凝胶合成方面的应用及其研究进展进行了综述。     

Single polymeric bubble for the preparation of multiple micro/nano fibers

Bubble‐electrospinning is suggested to produce micro/nano fibers. Contrary to classical electrospinning where a high voltage is applied to overcome the surface tension of the Taylor's cone, in bubble‐electrospinning, the voltage is applied to overcome the bubble's surface tension, which mainly depends upon the size of the bubble. Instead of single jet, millions of charged jets are observed simultaneously. In this article, we design a single bubble‐electrospinning to primarily study the effect of concentration on the spinning procedure. Polyvinylpyrrolidone (PVP) is used in the experiment. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Permeability control in polymeric systems: a review

Controlling the extent of permeant (gas/vapour/liquid) transport through a polymer is critical in packaging applications. This can be achieved by changing the chemical and physical nature of the polymer, blending the polymer with another, dispersing particulate, fibrillar or lamellar fillers, converting the microstructure of the polymer to a cellular one, or using an effective combination of all of these processes. This review critically analyses different methods of controlling polymer permeability reported in literature. It provides recommendations and fresh approaches for modification of polymer permeability when considering large scale manufacturing of packages with controlled permeability properties. In addition, the subsequent effects of these modification techniques on the mechanical properties of the polymeric system are considered.     

Synthesis and characterization of reactive copolymeric microgels

Hydrogels whose diameters range in the nanosize scale were synthesized by precipitation copolymerization of 4‐nitrophenol acrylate (NPA) with methacrylamide (MeAM) and N‐isopropylacrylamide (NIPAM). The polymerization reaction process was followed by attenuated total reflectance Fourier‐transform infrared spectrometry (ATR‐FTIR) and the conversion was studied by UV‐vis spectrometry. Poly(NPA‐co‐MeAM) and poly(NPA‐co‐NIPAM) microgels were characterized by proton nuclear magnetic resonance (¹H‐NMR) spectrometry. The thermal properties were studied by both thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis. Transmission electron microscopy (TEM) of these microgels showed that the copolymer is located in spherical particles with a moderate polydispersity. The average particle diameter and the particle size distribution were measured in acetone by quasi‐elastic light scattering (QELS), which indicated a mean diameter close to 50 nm. Copyright © 2005 Society of Chemical Industry     

Modified chitosan as a polymeric nanoreactor for fabrication of pure ZnO nano particles

ZnO nanoparticles have been prepared successfully by hydrogel decomposition method (HDM). Synthesized ZnO nanoparticles were characterized by X‐ray diffraction (XRD), fourier transforms infrared spectroscopy (FTIR), and transition electron microscopy (TEM) techniques. Narrow distribution of sizes with a 20–30 nm diameter and regular distribution of ZnO nanoparticles are attributed to the application of poly(acrylic acid‐co‐acrylamide) grafted chitosan hydrogel as coating agent. The results show that the polymer thermal decomposition technique is a perfect method for the synthesis of ZnO nanoparticles. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Reciprocity law experiments in polymeric photodegradation: a critical review

Accelerating the photodegradation of polymeric materials is of great practical interest in weathering research. Acceleration can be achieved by exposing polymeric materials to a high radiant flux; however, questions have arisen within the weathering community as to whether high radiant flux results can be extrapolated to in-service flux levels. Experiments designed to test this premise are called reciprocity law experiments. An extensive review has been conducted to assess the state-of-the-art of reciprocity law experiments in the photography, photoconductivity, photo-medicine, photobiology, and polymer photodegradation literatures. From this review, the Schwarzschild law (a power law generalization of the reciprocity law) appears to model adequately photoresponse vs. radiant flux for most materials and systems. A band theory model has been presented to explain variations in the Schwarzschild law coefficients and other experimental phenomena commonly associated with reciprocity experiments. Obstacles to the general acceptance of high radiant flux, laboratory-based experiments are discussed.     

Role of polymeric composite in civil engineering applications: a review

ABSTRACT

This is an up-to-date review on civil engineering application of polymeric composites filled with cement and fillers. Various combinations of polymer, glass fiber, and carbonaceous fillers have been considered as polymer/cement/carbon black, polymer/cement/carbon black/glass fiber, polymer/cement/carbon nanotube, polymer/cement/carbon nanotube/glass fiber, polymer/cement/graphite, and polymer/cement/graphite/glass fiber. These composites have gained significance due to high durability, dimensional stability, strength, non-flammability, and thermal characteristics. The cementitious composites have been applied in civil/infrastructural applications such as columns, beams/slabs for buildings, foundations, and bridges. Moreover, polymer/cement composites are used as basic construction material for neutron shielding, coal power plants, oil plants, water barrels, etc.     

新型磁性纳米锂离子筛的合成

采用狭道式撞击流反应器,将Fe₃O₄爆发式成核过程与快速包覆MnCO₃+Li₂CO₃薄膜的过程同步进行,制备出具有核壳结构的纳米Fe₃O₄/MnCO₃+Li₂CO₃前驱体;然后,通过在450℃下高温焙烧和稀酸酸浸脱锂工艺得到一种组成为Fe₃O₄/H_xMn_yO₄的磁性纳米锂离子筛。实验优化了爆发式成核过程与液相快速包膜过程的主要操作参数。采用BET、TEM、EDX、XRD等手段对产物进行了分析表征。结果表明,磁性纳米锂离子筛的平均粒径约为40 nm,比饱和磁化强度为27.581 emu·g^-1,磁矫顽力为相似文献   

Water retention in sandy substrates modified by cross-linked polymeric microgels and their complexes with a linear cationic polymer

New synthetic soil conditioners for anti-erosion protection of soils in the form of microgel copolymers of N-isopropylacrylamide and acrylic acid (PAA#) and their interpolyelectrolyte complexes (IPEC#) with different surface charges are tested for optimization of water retention and porous structure in two samples of soil substrates. Water retention curves (WRCs) are used as a fundamental thermodynamic indicator of water holding capacity in soil substrates treated by new polymeric materials. Soil-hydrological constants, as well as specific surface parameters and pore distribution curves are calculated from the WRCs using the van Genuhten model and the Voronin method in the author's modification. PAA# and anionic IPEC# with high swelling degree at a dose of 1% (by weight) increase field water capacity, available soil water range and specific surface area by 5–6 times for quartz sand, along with reorganizing its structure towards micropore dominance. For loamy sand, the same treatment was less effective with a twofold increase in field moisture capacity, double or triple increase of specific surface area, and an almost constant range of available soil water due to the strong increase of wilting point parameter. Weakly swelling linear polyacrylic acid and cationic IPEC# did not significantly affect properties of both mineral substrates.     

Poly(N-isopropylacrylamide-acrylic acid) copolymer microgels for various applications: A review

Smart polymer microgels have been attracting a lot of attention due to their quick response to variation in environmental stimuli like temperature, pH, ionic strength, and presence of some biological molecules. Poly(N-isopropylacrylamide) and its copolymer microgels have been synthesized and characterized for various applications in last 10 years. Synthesis, properties, and applications of poly(N-isopropylacryamide-co-acrylic acid) [P(NIPAM-AA)] copolymer microgels have been extensively reported in literature. This article describes synthesis, fundamental properties, and applications of P(NIPAM-AA) microgels in the field of medical science, environment, nanotechnology, catalysis, and photonics.     

端异氰酸酯基聚丁二烯/纳米二氧化硅弹性体的制备及其力学性能研究

以自制的端异氰酸酯基聚丁二烯(ITPB)为基体,纳米二氧化硅(SiO_2)为固化剂,制备了ITPB型聚氨酯/纳米SiO_2弹性体。阐述了ITPB/SiO_2弹性体的制备机理,研究了溶剂的种类、SiO_2加入量和固化条件对ITPB/SiO_2弹性体力学性能的影响。结果表明,以环己酮为溶剂制备的ITPB/SiO_2弹性体力学性能最佳;随着SiO_2加入量的增加,弹性体的拉伸强度、断裂伸长率、断裂强度及硬度均有明显提高,SiO_2加入量为6%时,弹性体的断裂伸长率达到最大值220.14%,当SiO_2加入量为8%时,弹性体的拉伸强度达到最大值7.11 MPa;提高固化温度和延长固化时间,有助于提高ITPB/SiO_2弹性体的力学性能。     

Synthesis of novel polymeric colorants

There are several structural types of polymeric dyes (polydyes) that have been synthesised as colorants for thermoplastic materials, particularly polyesters. This paper reviews three synthetic methods used to prepare polydyes. In method 1, anthraquinone polysulphonamide polydyes were prepared by reacting anthraquinonedisulphonyl chlorides with diamines in the presence of a base. Polymethine polydyes were prepared in method 2 by reacting bis-aldehydes containing two linked aromatic aldehyde moieties with a bis-(active methylene) component under Knoevenagel reaction conditions. In the final method, a variety of polymer types were synthesised by reacting acidic dyes containing two acidic groups with glycol sulphonates in the presence of a base. Most of the polydyes were evaluated as colorants for polyesters, by melt blending and extruding, followed by the preparation of films for further testing of properties such as fastness to light. The primary emphasis of this paper is to discuss the synthetic methods involved and to present the various types of structure that have been investigated.     

Synthesis and characterization of star-like microgels by one-pot free radical polymerization

A one-pot free radical polymerization process was used to prepare methyl acrylate/ethylene glycol dimethacrylate (MA/EGDMA) and methyl methacrylate/ethylene glycol dimethacrylate (MMA/EGDMA) polymers. The role of monomer and crosslinker reactivity ratios in producing different network structures was demonstrated. While both systems produced branched polymers that exhibited low intrinsic viscosities with little variation across a wide range of molecular weights, the star-like microgels formed between a less reactive monomer (MA) with a more reactive crosslinker (EGDMA) gave lower bulk solution viscosities than the more statistical polymers formed between similarly reactive monomers and crosslinkers (MMA and EGDMA). This paper presented a simple and cost-effective synthetic route for the production of polymers with high molecular weight and low viscosity with considerable potential for industrial-scale processing.     

Synthesis of poly(vinyl alcohol) core-polystyrene shell-type flower microgels

Four types of poly(vinyl alcohol-b-styrene-b-vinyl alcohol) (P(VA-b-S-b-VA)) triblock copolymers were synthesized by hydrolysis of poly(vinyl acetate-b-styrene-b-vinyl acetate) triblock copolymers prepared by radical living polymerization. The polyvinyl alcohol (PVA) core-polystyrene corona-type flower micelles were formed with ASA-4 in benzene at 25°C. The PVA core part of the micelle was crosslinked with hexamethylene diisocyanate in solution. The monodispersed spherical products (microspheres) were synthesized by crosslinking. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 849–854, 1997     

聚合表面活性剂的合成及其应用

综述了近二十年来聚合表面活性剂的合成及主要应用,详细阐述了国内外对低聚表面活性剂在合成、界面吸附和溶液聚集行为方面的研究进展.已有的研究结果表明,中低分子质量的线性聚合表面活性剂不但具有很高的界面活性,可以使原油/水的界面张力达到超低,而且兼具一定的黏度,在三次采油上将具有很大的应用前景.     

Surface modification of textile fibers for improvement of adhesion to polymeric matrices: a review

Surface treatments have long been utilized to modify the chemical and physical structures of the surface layers of textile fibers, thus improving the properties of fibers in many applications. This review discusses the feasibility and characteristics of different methods of surface modification of polymeric textile fibers, focusing on tailoring fiber-matrix bond strength in fiber-reinforced composite materials. The influence of various treatments on the chemical and mechanical properties of different fibers is discussed. Some very recent developments in surface modification of textile fibers are highlighted.     

丙烯酸酯类反应性微凝胶的制备及其对环氧树脂的增韧作用

采用自稳定分散聚合法,制备了粒径在20nm左右、粒径分布均匀的球形丙烯酸酯类反应性微凝胶;同时研究了其对环氧树脂/间苯二胺(MPDA)体系的增韧效果.结果表明,所制备的丙烯酸酯类反应性微凝胶在室温下呈橡胶态;它是环氧树脂/MPDA体系的一种有效增韧荆,增韧效果受其用量、官能团种类及用量的影响;含有环氧基团的微凝胶颗粒,增韧效果最好,而且提高了环氧树脂的热性能:带有环氧基团的微凝胶颗粒用量越大,或丙烯酸酯类微凝胶中环氧基团的摩尔分数越高,对环氧树脂的增韧效果越好.     

两性型高分子絮凝脱色剂PAM/AMPS/DMDAAC的合成与表征

以非离子单体丙烯酰胺(AM)、阴离子单体2-丙烯酰胺基-2-甲基丙磺酸(AMPS)和阳离子单体二甲基二烯丙基氯化铵(DMDAAC)为原料,以过硫酸铵、亚硫酸钠、2,2'-偶氮二异丁基脒二盐酸盐为引发荆,合成了絮凝剂产品PAM/AMPS/DMDAAC.在单体质量分数为10%的条件下,得到了最佳的合成工艺为:m(AM):m(DMDAAC):m(AMPS)=7:2:1,反应温度为45℃,偶氮引发剂2,2'-偶氮二异丁基脒二盐酸盐用量为溶液质量分数的0.006%,过硫酸铵用量为溶液质量分数的0.004%,哑硫酸氢钠用量为溶液质量分数的0.002%;对PAM/AMPS/DMDAAC的结构进行红外光谱和透射电镜表征,表明PAM/AMPS/DMDAAC链节上含有季铵盐和磺酸盐基团,分子呈现长链结构,分子链刚性好,交联现象少.