聚合物磁性纳米微球的研究综述

聚合物磁性纳米微球不仅具有无机的磁性,又兼具有机表面的可修饰性,是一种很有前途的载体材料。本文对聚合物磁性纳米微球近年来在生化分离、催化、医学、环境等领域的应用进行了综述,并对其未来的研究进行了展望。     

核壳聚合物微球的制备方法及应用

综述了近年来核壳结构聚合物微球制备方面的研究进展,介绍了乳液法、自组装法、模板法、沉积法等主要制备方法,阐述了各种方法所涉及的机理.介绍了目前核壳聚合物微球的应用现状,如制备中空微球、用磁性核壳微球提高医学诊断的准确率及作为填料改性聚合物等,表明核壳微球有着广阔而重要的应用前景.     

热膨胀聚合物微球的制备、性能及应用

从热膨胀聚合物微球的基本组成、合成工艺、性能等方面进行概述,并详细阐述了热膨胀聚合物微球在诸如轻量化、表面修饰、隔热隔声、粘接解粘等方面的应用,并对其未来发展进行了展望.     

生物可降解聚合物多孔支架的制备研究进展

组织工程的关键技术之一在于运用生物可降解聚合物制备出具有特定结构、内部连通性好并具有良好力学性能的三维多孔支架,本文对近几年来制备支架的方法以及研究热点做了综述,并对组织工程用生物可降解聚合物多孔支架的发展方向做了展望。     

纳米二氧化硅微球的应用及制备进展

纳米二氧化硅微球在电子、光学器件、化学生物芯片、催化等领域有着广泛的应用.本文综述了近几年纳米二氧化硅微球几种制备方法,例如:溶胶-凝胶法、模板法、沉淀法、超重力法、微乳液法等,并对这些工艺方法的优缺点做了简单评述,最后对二氧化硅的应用前景进行了展望.     

聚合物中空微球的研究进展

中空结构聚合物微粒具有低密度、高比表面积、稳定性好且可以容纳客体分子等特点在众多领域受到广泛关注。本文对聚合物中空结构微球的制备方法进行了综述,并简要介绍了聚合物中空微球在多个行业中的应用。     

微囊微球的物理化学制备技术及其应用研究进展

介绍了制备微囊微球常用的两种物理化学方法-相分离法和溶剂蒸发法,以及微囊微球在避抗微生物、生物药物释放方面的应用,重点阐述了以可生物降解材料为壁材,以生物药物制剂、植物的天然提取物为芯材进行微囊化方面的研究及应用进展。     

分子印迹聚合物微球的制备及应用进展

评述了分子印迹原理、分子印迹聚合物微球的制备技术以及一些制备新方法，并对其应用领域作了较为详细地介绍。     

分散聚合及单分散聚合物微球制备技术

分散聚合是一种新的聚合方法 ,反应开始前 ,单体、引发剂和分散剂均溶解在介质中 ,随着反应的进行 ,当聚合物链达到临界值时便会从介质中分离出来 ,并借助于分散剂稳定地悬浮在介质中。分散聚合方法已被应用于许多领域 ,如涂料工业、生物工程、医学、信息产业、化学工业等。介绍了分散聚合及单分散聚合物微球制备技术的进展 ,并对其聚合机理及聚合反应影响因素进行了概述。     

微囊化载药高分子微球制备方法研究进展

本文综述了各种微囊化制备微球的方法和原理，并对微囊化微球技术的研究最新进展及其在纳米微球，磁性高分子微球、智能微球制备上的应用作了介绍。     

Polyhydroxyalkanoates: biodegradable polymers with a range of applications

Increased and accelerated global economic activities over the past century have led to interlinked problems that require urgent attention. The current patterns of production and consumption have raised serious concerns. In this context, greater emphasis has been put on the concept of sustainable economic systems that rely on technologies based on and supporting renewable sources of energy and materials. Average UK households produce around 3.2 million tonnes of packaging waste annually whereas 150 million tonnes of packaging waste is generated annually by industries in the UK. Hence, the development of biologically derived biodegradable polymers is one important element of the new economic development. Key among the biodegradable biopolymers is a class known as polyhydroxyalkanoates. Polyhydroxyalkanoates (PHAs) are a family of polyhydroxyesters of 3‐, 4‐, 5‐ and 6‐hydroxyalkanoic acids, produced by a variety of bacterial species under nutrient‐limiting conditions with excess carbon. These water‐insoluble storage polymers are biodegradable, exhibit thermoplastic properties and can be produced from renewable carbon sources. Thus, there has been considerable interest in the commercial exploitation of these biodegradable polyesters. In this review various applications of polyhydroxyalkanoates are discussed, covering areas such as medicine, agriculture, tissue engineering, nanocomposites, polymer blends and chiral synthesis. Overall this review shows that polyhydroxyalkanoates are a promising class of new emerging biopolymers. Copyright © 2007 Society of Chemical Industry     

Preparation of biodegradable polymer microspheres encapsulating protein with micron sizes

Biodegradable polymer poly-D,L -lactide-polyethylene glycol (PLA-PEG) was synthesized with stannous octoate (SnOc₂) as catalyst by a cationic ring-opening polymerization. The molecular weight of PLA-PEG is the highest at a content of 0.1% SnOc₂. The PLA-PEG microspheres carrying protein were prepared by a solvent evaporation composite emulsion technique with a narrow size range (1–2 μm). The sizes of PLA-PEG microspheres increased with the increase of the molecular weight of PLA-PEG. The PEG in PLA-PEG (10%) significantly improved the size control of the microspheres of the PLA family as a drug carrier matrix. Polyvinyl alcohol (PVA) aqueous solution was used as dispersion medium for microsphere preparation. The concentration of the PVA solution can affect the size of the PLA-PEG microspheres. The differential scanning calorimetry data showed that the PLA-PEG microspheres can efficiently encapsulate the protein and that the crystalline of the microspheres carrying protein was lower than that of the nonprotein-loading microspheres. The amount of protein carried in the PLA-PEG microspheres was related to the nature of the protein itself. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 583–590, 1997     

Preparation and characterization of electrospun,biodegradable membranes

Nonwoven, biodegradable membranes fabricated by electrospinning have recently attracted a great deal of attention for biomedical applications. In this study, microporous, nonwoven membranes of poly(L ‐lactide) and its copolymers and blends were fabricated through electrospinning. The structures and morphologies of the electrospun membranes were investigated with scanning electron microscopy, differential scanning calorimetry, and X‐ray diffraction. Different polymer membranes, incorporated with carmofur, were fabricated, and their drug release profiles were investigated. Scanning electron microscopy images showed that the fiber diameters were down to the nanometer range. The diameters and morphologies of thenanofibers depended on processing parameters such as the solution properties (concentration and polymer molecular weight), applied electric voltage, solution feeding rate, and needle diameter. Differential scanning calorimetry showed that the crystallinity of the electrospun membranes was lower than that of the cast film. For all the membranes incorporated with the drug, there was a burst release in the first 10 h of incubation in phosphate‐buffered saline at 37°C. Poly(glycolide‐co‐lactide) membranes showed faster and more complete drug release than poly(L ‐lactide), and this could be attributed to its faster degradation. The incorporation of polylactide–poly(ethylene glycol) could shorten the drug release time. A combination of suitable degradable biomaterials with an appropriate electrospinning process could be useful in the fabrication of a new kind of membrane suitable for different biomedical applications such as tissue engineering and drug delivery. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

工程塑料改性及成型加工技术特集之六液晶聚合物改性及应用

就利用液晶聚合物特性的新材料开发，对高循环成型材料和流动性和机械物性同时改性的填料应用、耐热新规格聚合物的骨架、精密成型材料及其回收再生适应性作了说明。     

Materials selection and residual solvent retention in biodegradable electrospun fibers

Electrospun tissue engineering scaffolds provide mechanical support to seeded cells that populate the structure while depositing specific extracellular matrix components. The potent sterilizing agent 1,1,1,3,3,3‐hexafluoro‐2‐propanol (HFIP) is often used in electrospinning investigations involving biologically‐derived polymers. Surprisingly, there has been no study of solvent retention versus composition even though materials selection should influence organic solvent content. We developed a method quantifying HFIP retention following electrospinning of gelatin, polycaprolactone (PCL), and PCL‐gelatin blends using electro‐spray mass spectroscopy. The acetone content of acetone‐spun PCL was also established. Pure gelatin fiber contained as much as 1600 ppm of HFIP. In contrast, little acetone or HFIP was detected in 100% PCL. Gelatin clearly has a greater affinity for HFIP than PCL and materials selection has a strong influence on the amount of retained solvent. Vacuum + heat treatment at 37 and 45ºC reduced [HFIP] to 10 and 5.6 ppm, respectively, levels having no demonstrated effects on mammalian cell viability. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

pH‐reversible magnetic gel with a biodegradable polymer

Polymer gels that react to external stimuli, such as pH, temperature, and electromagnetic fields, are an important class of materials. Such materials have pharmaceutical, industrial, and biomedical applications. Our intention in this study was to synthesize a stimuli‐responsive polymer gel with a biodegradable polymer. However, the chemical crosslinker, divinyl sulfone, which is most widely used for the crosslinking of this type of material, is highly toxic in nature. To overcome this problem, a reversible magnetic gel was synthesized with hydroxy propyl cellulose (HPC) and maghemite at pH 13 without with a chemical crosslinker. With a decrease in pH from 13 to 9, the gel formed a homogeneous dispersion of HPC particles with maghemite in it. This process was a reversible physical gelation where the crosslinks of the network had a physical origin (in this case, hydrogen bonding) and, therefore, were sensitive to variations in pH. When this physically prepared gel was compared with the chemically crosslinked one, no significant differences in structural properties were noted. At higher pH values, the gel was formed due to weak intermolecular hydrogen bonding, as observed by the broadening of the IR band in both the magnetic and nonmagnetic gels. Transmission electron micrographs also showed no significant difference in the gel morphology. Differential scanning calorimetry showed an increase in melting temperature for the gel sample compared to that of pure HPC. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3337–3341, 2004     

Field performance on lettuce crops of poly(butylene adipate-co-terephthalate)/polylactic acid as alternative biodegradable composites mulching films

This work developed biodegradable poly(butylene adipate-co-terephthalate)/polylactic acid (PBAT/PLA) composites with different fillers to improve their physicochemical properties and biodegradability. The films were tested considering mechanical, morphological, thermal, crystalline, biodegradability, and ecotoxicity tests. Mechanical and morphological results indicated that the fillers' nature influences mechanical performance; all composites showed high-tensile strength (~30 MPa) than the pristine films (~12 MPa). The use of both fillers resulted in an interface, improving the matrix compatibility, reflecting in good thermal performance, low-water absorption, and high hydrophobicity. The WA (water absorption) and hydrophobicity are essential to maintain the crop's moisture since the water lost through plant transpiration will be condensed and returned to the soil. Films showed biodegradability and absence of toxicity, which allows the substitution of polyethylene commodity films as mulching films. Biodegradation and ecotoxicity tests indicate that the developed films are beneficial for lettuce crops and contribute to the development of seedlings.     

Current application of controlled degradation processes in polymer modification and functionalization

Ecological concerns over the accumulation of polymeric waste material and the demand for functionalized polymers in specialty applications have promoted extensive research on different controlled degradation processes and their use. The production of functionalized or modified polymers by conventional synthetic routes is expensive and time consuming. However, advances in degradation technology have become an enabling factor in the production of modified polymers and their functionalization. Mild irradiation, ozonization, and enzymatic routes are among the processes that have been explored for polymer modification. Biopolymers, such as chitosan, hyaluronic acids, and polyhydroxyalkanoates, are known to be suitable for a diverse number of applications, ranging from biomedical to organic‐electronics. At the same time, their high molecular weight, crystallinity, and shelf degradability limit their utility. Controlled degradation processes can be used to prepare these types of polymers with reasonably low molecular weights and to generate radical species that help to stabilize these polymers or to initiate further beneficial reactions. In this article, we review the application of controlled degradation processes for polymer modification and functionalization. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis of pH-sensitive hollow polymer microspheres and their application as drug carriers

The pH-sensitive hollow poly(N,N′-methylene bisacrylamide-co-methacrylic acid) (P(MBAAm-co-MAA)) microspheres were prepared by a two-stage distillation precipitation polymerization to afford a core-shell poly(methacrylic acid)/poly(N,N′-methylene bisacrylamide-co-methacrylic acid) (PMAA/(P(MBAAm-co-MAA))) microsphere with subsequent removal of poly(methacrylic acid) (PMAA) core. PMAA/P(MBAAm-co-MAA) core-shell microspheres were synthesized by the second-stage copolymerization of N,N′-methylene bisacrylamide (MBAAm) as crosslinker and the functional methacrylic acid (MAA) comonomer in acetonitrile with 2,2′-azobisisobutyronitrile (AIBN) as initiator. The pH-responsive properties of hollow P(MBAAm-co-MAA) microspheres were investigated by dynamic laser scattering (DLS). The loading and controlled-release behavior of the drug for hollow P(MBAAm-co-MAA) microspheres was strongly dependent on the pH values with doxorubicin hydrochloride (DXR) as a model molecule. The core-shell and hollow polymer microspheres were characterized by transmission electron microscopy (TEM), Fourier-transform infrared spectra (FT-IR), DLS and elemental analysis.     

Compositional analysis of biodegradable polyphosphoester copolymers using nmr spectroscopic methods

The chemical composition and quantitative molar ratios among all components of biodegradable polyphosphoester copolymers of DL ‐lactide and ethylphosphate were determined by a comprehensive set of NMR spectroscopic methods. The polyphosphoester copolymers studied were synthesized using condensation polymerization of oligomeric DL ‐lactide prepolymers and ethyl dichlorophosphate. Conclusive identification of the chemical shift patterns of all functional groups in the copolymers required additional NMR methods such as ³¹P‐NMR and two‐dimensional ¹H–¹H COSY NMR, in addition to the synthesis and comparative NMR analysis of model compounds possessing identical phosphoester linkages in the polyphosphoester copolymers. For the polymers synthesized using the bulk polycondensation process, ¹H–¹H COSY NMR analysis revealed the presence of a small amount of side products that were undetected by ¹H‐NMR alone. These side reactions most likely occurred between the pendant ethoxy group of the phosphoesters and the hydrogen chloride gas generated in the bulk polycondensation process. ³¹P‐NMR spectra of the copolymers revealed a consistent triple‐peak pattern characteristic of phosphoesters linked to a racemic mixture of D,L ‐lactides. These results offered new insight into the side reactions occurring in bulk polymerization of polyphosphoesters and provided a powerful tool of characterizing complex biodegradable polymers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 4021–4031, 2003