Ruthenium-centered thermosensitive polymers

Bipyridine-centered poly(N-isopropylacrylamide) polymers with controlled molecular weight and low polydispersity were synthesized by RAFT polymerization using a novel bipyridine-functionalized dithioester as a RAFT agent, and were further complexed with ruthenium ion to produce ruthenium-centered thermosensitive polymers with well-defined structure. Results from UV-vis, fluorescence and DSC characterizations of the thermosensitive polymeric ruthenium complexes indicated that tris(2,2′-bipyridine)ruthenium(II) ion was successfully grafted onto the center of polymer chains.     

Synthesis of thermosensitive polymers containing sugar branches

Copolymers of 6‐O‐vinyladipoyl‐D ‐glucose (VAG) and N‐isopropyl acrylamide (NIPAm) were synthesized by radical polymerization. The number‐average molecular weights of the copolymers were 3 × 10⁴ ≈ 6 × 10⁴. The observed segment composition of copolymers at the feed molar ratio (VAG 25/NIPAm 75) was VAG 10/NIPAm 90. The polymerization rate of the VAG monomer was slower than that of the NIPAm monomer. The lower critical‐solution temperature of copolymers measured with a light‐scattering photometer and a differential scanning calorimeter increased with increasing VAG segment composition. The increase in transition temperature was accompanied by a decrease in transition heat. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 384–387, 2001     

Optimized flurbiprofen cationic liposomes in situ gelling system of thermosensitive polymers for ocular delivery

A Flurbiprofen (FP) cationic liposomes in situ gelling system (CLIGS) of thermosensitive polymers was proposed; we investigated its in vitro and in vivo properties, and its potential use in ocular drug delivery was evaluated. This system, optimized via center composite design, was conceived from a combination of polymer‐ and lipid‐based delivery systems. Therefore, the system could integrate the advantages of both cationic liposomes and in situ gels and further improve the poor stability of cationic liposomes. Cationic liposomes were characterized for their particle size, shape, entrapment efficiency, ζ potential, and photograph of transmission electron microscopy. The in vitro penetration capability and precorneal retention time of the FP CLIGS were evaluated by a vertical Franz‐type cell method and γ scintigaraphy, respectively. The FP CLIGS showed an improved stability during a 30‐day storage period over than of FP cationic liposomes. In conclusion, CLIGS serves as a means to overcome a major limitation of cationic liposomes with a prolonged precorneal retention time, enhanced stability, and convenient administration due to the modified gelatinization temperature; this justifies their use as a carrier adjuvant for ocular delivery behaviors. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

石墨填充聚乙烯醇膜渗透蒸发分离苯和环己烷

采用液相共混法制备了石墨填充聚乙烯醇膜,采用FTIR,SEM,XRD等对石墨填充聚乙烯醇膜的物理和化学结构进行了分析表征,结果表明石墨与聚乙烯醇存在较强的氢键作用,石墨在聚乙烯醇中分散均匀,且具有一定的取向性.考察了石墨填充聚乙烯醇膜在苯和环己烷溶液中的溶胀和吸附行为.采用正电子湮没寿命谱仪表征了石墨聚乙烯醇膜的自由体积特性,计算得到石墨聚乙烯醇膜的表观自由体积分数,并且与渗透通量进行关联性对比.最后,研究了石墨含量和粒径对渗透蒸发分离性能的影响,结果表明,石墨的引入有利于苯的优先透过,石墨填充聚乙烯醇膜对苯和环己烷混合物具有良好的分离效果,苯的渗透通量和分离因子分别可达90.7 g•m^-2•h^-1和100.1.     

Photo-swing extraction system for lanthanide separation by a thermosensitive polymer gel combined with carbon nanotubes

A novel photo-swing extraction system for lanthanide separation was developed using an acid phosphoxy ethyl methacrylate (Phosmer-M) copolymerized thermosensitive polymer gel and N-isopropylacrylamide (NIPAM) combined with single-walled carbon nanotubes (CNTs) as the extracting material. The swelling and shrinking phase transition of the Phosmer-M/NIPAM/CNT gel was successfully induced by photo-irradiation with a halogen lamp because of the heat generation by the CNTs, which occurred upon visible light absorption. The extraction ability of Eu(III) increased upon photo-irradiation because of changes in the volume and hydrophobicity of the composite gel. The ratio of the distribution coefficient with and without photo-irradiation (K_dphoto/K_d25) increased with an increase in the pH. The composite gel possessed sufficient loading and release capacities for Eu(III), La(III) and Lu(III) in repeated processes after photo-irradiation. The selectivity for Eu(III) over La(III) in binary metal systems increased due to photo-irradiation because the observed improvement in the extraction of Eu(III) was greater than that of La(III) during the phase transition of the gel.     

Physicochemical modification of hydroxylated polymers to develop thermosensitive double network hydrogels

Due to the unique biophysicochemical characteristics of synthesized superhydrophilic poly[N-[tris(hydroxymethyl)methyl] acrylamide] (PTHMMA) and poly(vinyl alcohol) (PVA), in this study, we investigated the preparation of physically and chemically crosslinked thermosensitive double network (DN) hydrogels with superior mechanical properties. The effect of the combination of PTHMMA with PVA was further explored experimentally and theoretically. Moreover, adjusting the lower critical solution temperature (LCST) of PTHMMA/PVA DN hydrogels in the phosphate buffer was achieved by chemical alteration and crosslinking of water-soluble polymers. Changing the composition and the extent of ether/acetal linkages altered the LCST based on hydrophilic/hydrophobic composition, which decreased the complexity of adjusting hydrogels' temperature sensitivity. PTHMMA-comprising hydrogels were found to have non-Fickian and super case ΙΙ transport characters. Moreover, the construction of shrunken PVA at high temperature was tailored by introducing PTHMMA into the network to permit a relaxed drug release of indomethacin (IND) at 37°C and pH 7.4. Finally, the tensile strength, the equilibrium water content, thermo-sensitivity, and cell viability behaviors suggest that these materials can be tailored for potential applications as biomaterials.     

Pervaporation separation of ethanol/water mixture using modified zeolite filled PDMS membranes

In this article, the composite polydimethylsiloxane (PDMS) membranes supported by cellulose acetate (CA) microfiltration membrane were successfully prepared by adding modified zeolite particles with a silane coupling agent, NH₃–C₃H₆–Si(OC₂H₅)₃. The sorption and diffusion behaviors of ethanol and water in the films were studied. The results showed that with the increase in the modified zeolite content, the solubility selectivity increased, but the diffusion selectivity first increased, then decreased. The effects of modified zeolite content and feed temperature on the pervaporation performance of the composite membranes in 10 wt % ethanol/water mixture were also investigated. When modified zeolite loading was 20 wt %, for 10 wt % ethanol/water mixture at 40°C, the permeate flux was 348.7 g·m^?2·h^?1, the separation factor was 14.1, and the permeate separate index was 4568, respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41897.     

Construction of PS/PNIPAM core-shell particles and hollow spheres by using hydrophobic interaction and thermosensitive phase separation

Abstract This paper reports an easy and effective way to fabricate polystyrene/poly (N-isopropylacrylamide) (PS/ PNIPAM) core-shell particles and PNIPAM hollow spheres. The main point of the method is to take advantage of the hydrophobic interaction between initiator and PS particles. The hydrophobic azodiisobutyronitriles automatically concentrate around the PS particles and initiate polymerization of N-isopropylacrylamide (NIPAM) and the crosslinkermethylene bisacrylamide (MBA), which dissolve in the aqueous phase, at the surface of the PS nanoparticles. Then, PNIPAM adheres to the PS particles to form a coreshell structure as a result of their hydrophobic interaction. This interaction is due to the unique property of PNIPAM, namely, its ability to transition from hydrophilic to hydrophobic when the temperature rises to 32°C. Furthermore, the hollow PNIPAM spheres were obtained by etching the PS core with chloroform. __________ Translated from Journal of Nanjing University (Natural Sciences), 2007, 43(5): 483–488 [译自: 南京大学学报(自然科学)]     

Construction of PS/PNIPAM core-shell particles and hollow spheres by using hydrophobic interaction and thermosensitive phase separation

This paper reports an easy and effective way to fabricate polystyrene/poly (N-isopropylacrylamide) (PS/PNIPAM) core-shell particles and PNIPAM hollow spheres. The main point of the method is to take advantage of the hydrophobic interaction between initiator and PS particles. The hydrophobic azodiisobutyronitriles automatically concentrate around the PS particles and initiate polymerization of N-isopropylacrylamide (NIPAM) and the crosslinker methylene bisacrylamide (MBA), which dissolve in the aqueous phase, at the surface of the PS nanoparticles. Then, PNIPAM adheres to the PS particles to form a core-shell structure as a result of their hydrophobic interaction. This interaction is due to the unique property of PNIPAM, namely, its ability to transition from hydrophilic to hydrophobic when the temperature rises to 32°C. Furthermore, the hollow PNIPAM spheres were obtained by etching the PS core with chloroform.     

Adsorption/desorption of protein on magnetic particles covered by thermosensitive polymers

The adsorption and desorption behavior of protein human serum albumin (HSA) on magnetic polymer particles covered by thermosensitive polymers was investigated. The results showed that adsorption was dependent mainly on the properties of the particle surface. By increasing the temperature, particles deswelled and were susceptible to absorb larger amounts of proteins, which could be desorbed at lower temperature. The extent of adsorption was found to depend on the pH value, protein concentration, and incubation time. At higher pH, a smaller amount of proteins could be absorbed because of the electrostatic repulsive force between the protein and the surface particles. Increasing incubation time or initial protein concentration was favorable to the adsorption of proteins. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2915–2920, 2000     

渗透汽化在酯水体系分离中的应用

概述了渗透汽化膜分离技术在酯水体系分离中的应用,着重介绍了渗透汽化-酯化反应耦联膜反应器的动力学模型、膜材料、膜组件及其工业应用实例,指出了新的膜材料的开发与改性、以及全新概念的膜组件设计将是今后膜技术在食品工业中应用研究的重点。     

沉淀聚合法制备VCL／NVP温敏型微凝胶及其性能研究

用沉淀聚合法,以N-乙烯基己内酰胺（VCL）和N-乙烯基吡咯烷酮（NVP）为共聚单体、N,N-亚甲基双丙烯酰胺（MBA）为交联剂,通过改变交联剂的量制备了-系列不同粒径的温敏型微凝胶。用纳米颗粒力度分析仪（DLS）和原子粒显微镜（AFM）对凝胶进行了表征。结果表明：粒子为球型单分散;在15—55℃范围内凝胶粒径随温度升高而减小,具有温度敏感性,最低临界转变温度（LCST）为35℃;交联剂的量不改变最低临界转变温度,只改变粒子大小。     

多糖类亲和分离材料的研究进展

亲和分离技术的核心是设计亲和分离材料,基于分子识别与亲和机制,针对多糖类高分子化合物的结构特点,探讨了其材料的设计原则,并综述了国内外多糖类亲和分离材料的制备技术及其应用研究进展。在此基础上提出了进一步改进多糖类高分子化合物制备技术的措施,并展望了此类材料的应用前景。     

硅氟两亲聚合物在柴油/水体系中的分水效能及机理

对4种含氟链段聚合度不同的硅氟聚合物在柴油/水体系中的分水效能进行了评价,并通过界面张力和界面黏弹性研究了其分水机理。结果表明,随着含氟链段聚合度的增加,其油水分离时间先减小后增大。含氟单体平均聚合度为16的聚合物质量浓度为0.2g/L时,在23s内实现柴油/水的完全分离。界面张力不是影响分水效能的主要因素,该类聚合物主要通过降低界面膜黏弹性实现有效分水。     

Properties of heteroaromatic polymers for gas separation

Summary The gas separation properties of new aromatic polyoxadiazole (POD) and polytriazole (PT) membranes have been investigated. A wide range of permeability and selectivity was found for polymers with 4,4-diphenyl-ether unit (POD-DPE and PT-DPE), 4,4(2,2-diphenyl)hexafluorisopropane (POD-HF), 1,1,3-trimethyl-3-phenylindane (POD-PIDA) and 5-tert-butylisophthalic (POD-TBI) units incorporated into the backbone. The differences found in permeability and selectivity, as well as the dual sorption parameters of POD-PIDA and POD-DPE polyoxadiazoles are discussed in terms of their free volume determined by group contribution.     

三元混合物分壁塔精馏分离的研究

提出了甲醇-乙醇-正丙醇三元混合物分壁塔精馏分离的新工艺。通过模拟和灵敏度分析,考察了分壁塔的进料位置、隔板位置、液体分配比、回流比等工艺参数对分离效果的影响,确定了分壁塔的最佳操作条件,并对分壁塔的能耗进行了分析。结果表明,单个分壁塔能达到常规三元混合物分离的要求,并且比常规精馏流程的分离过程节能约30%。     

Protein separation mechanisms in surfactant precipitation systems

Separation of globular proteins (cytochrome c and ribonuclease A) from buffer using precipitation by sodium bis-(2-ethylhexyl) sulfosuccinate (AOT), and their recovery with a counterionic surfactant, trioctylmethylammonium chloride (TOMAC) was investigated. The molar ratio between AOT and the protein (R) required for complete removal was 17 for cytochrome c, and 22 for ribonuclease A. Finally, three mixtures of the two proteins and lysozyme (studied earlier by us) were used to determine the factors controlling separation: selectivity was a strong function of surface charge distribution, indicating that charge interactions between the surfactant and surface groups of different proteins was driving precipitation.     

DMC-甲醇-水三元混合物的萃取精馏分离工艺

运用Aspen Plus软件回归文献数据校正了碳酸二甲酯（DMC）-水（H₂O）混合物的UNIQUAC热力学模型参数,并以该模型为基础分析了水作为萃取剂萃取精馏分离DMC-甲醇（CH₃OH）-水三元混合物的分离原理,结合混合组分的三角相图和物料组成设计了反向萃取精馏工艺,发现选用水为萃取剂可以利用DMC-水的部分互溶特性,通过三塔精馏即可分离DMC-甲醇-水三元混合物,沸点较高的DMC和少量水由塔顶馏出,而沸点较低的甲醇和大部分水由塔底采出,避免了DMC-甲醇二元共沸物的形成。同时,在相同分离要求下设计了变压精馏工艺,通过对两个精馏工艺参数模拟优化,发现萃取精馏工艺的总冷凝负荷和总加热负荷分别为888.7kW和898.2kW,其总能耗较变压精馏工艺节约了47.2%,萃取精馏工艺的年总费用（TAC）比变压精馏工艺下降了48.8%。     

变压精馏乙醇苯混合物分离工艺模拟计算

乙醇苯混合物是一种二元最低共沸液体混合物。研究了变压精馏分离乙醇苯工艺流程,以W ilson活度系数方程作为物性计算方法,使用过程模拟软件Aspen P lus对整个分离流程进行模拟计算,以系统能耗最低为目标,对重要的工艺参数进行了优化,提出的工艺方案可为工艺装置设计提供理论参考。