含mPEG侧链的水溶性梳状聚合物的合成及其侧链受限结晶行为研究

采用大单体与小单体共聚的技术,通过自由基引发溶液聚合,合成了一系列水溶性梳状聚合物———聚丙烯酸接枝聚乙二醇单甲醚(PAA-g-mPEG).制备过程分两步进行,首先合成大单体聚乙二醇单甲醚丙烯酸酯,然后将大单体与丙烯酸单体共聚,合成了梳状聚合物.通过控制反应条件,获得了一系列主链和支链组成比不同的接枝共聚物.用傅立叶变换红外光谱(FT-IR)和核磁共振氢谱(1H-NMR)表征了共聚物的结构,并对其侧链的结晶行为进行了研究.采用差热扫描量热法(DSC)表征并分析了不同侧链长度的mPEG的热性能及其结晶情况.利用相差显微镜和原子力显微镜(AFM)观察薄膜的结晶形貌,表明梳状聚合物的侧链mPEG在受限条件下的薄膜结晶形貌为高度支化的晶体,初步分析了mPEG链长及其在共聚物中的重量百分含量对晶体形貌的影响.     

共聚理论进展

凡由两种或多种单体构成链节的高聚物称为共聚物,而合成此类聚合物的过程叫做共聚反应。按聚合反应机制可分为自由基型和离子型两种。根据生成的共聚物链结构序列的不同,则可分为无规共聚、交替共聚、嵌段共聚和接枝共聚。本世纪初发现了共聚现象。早期主要研究了异戊二烯和丁二烯,丁二烯与苯乙烯和丙烯腈,以及一系列烯类和双烯类单体的共聚反应,并且得到了一些有价     

含有三氟乙烯基芳基醚侧基的聚丙烯酸酯的合成与表征

研究了聚丙烯酸酯侧基上引入三氟乙烯基芳基醚结构单元的方法. 首先, 合成了含有三氟乙烯基芳基醚侧基的丙烯酸酯单体, 然后通过原子转移自由基聚合实现了该单体的均聚和无规共聚, 得到了含有三氟乙烯基芳基醚侧基的聚丙烯酸酯聚合物, 聚合物的分子量分布较窄. 通过控制共聚投料比, 可以得到具有不同含量三氟乙烯基芳基醚侧基的无规共聚物.     

丙烯/1-丁烯和丙烯/乙烯无规共聚物的表征及性能研究

采用摩尔含量接近的两个单体乙烯和1-丁烯分别无规共聚聚丙烯样品,用三氯苯进行室温可溶物和不溶物的分离,采用凝胶渗透色谱、13C核磁共振波谱及热分析等方法对两种共聚聚合物及其分离物进行表征,探讨了乙烯和1-丁烯作为共聚单体对聚丙烯树脂结构和性能的影响.结果表明,与乙烯相比,1-丁烯更趋向于共聚在较长的聚丙烯分子链上,其结果导致丙烯/1-丁烯无规共聚聚丙烯的可溶物含量更低.同时,对两种无规共聚物结晶性能的差异以及对光学性能和动态力学性能的影响研究表明,如果共聚单体含量接近,丙烯/1-丁烯无规共聚物结晶度更高;透明制品雾度相同时,丙烯/1-丁烯无规共聚物的刚性更高.     

聚膦腈-g-聚己内酯共聚物的合成与表征

通过三甲基碘硅烷与聚二(2-甲氧基乙氧基)膦腈侧链上的醚键反应后水解得到侧链含部分羟基的聚膦腈,然后利用聚膦腈的侧链羟基在异辛酸亚锡催化作用下,引发己内酯单体开环聚合制备了聚膦腈-g-聚己内酯共聚物.该共聚物中聚己内酯链段的接枝率和侧链长度可通过改变三甲基碘硅烷和己内酯单体的投料来控制.     

丙烯酰胺-二氰二胺大单体及其与苯乙烯共聚物的研究(Ⅰ)——大单体及其共聚物的合成和表征

通过丙烯酰胺、二氰二胺、甲醛及氯化铵的缩合反应,合成了分子链端含C=C双键的大单体,缩合过程用高压液相色谱考察,以AIBN为引发剂,二甲基亚砜为溶剂,使大单体与苯乙烯共聚,得到主链具有疏水性、侧链具有亲水性的共聚物,用GPC、IR光谱及溶解性对共聚物进行鉴定,苯乙烯含量较低时,共聚物溶于水,共聚物在MeOH/H₂O混合溶剂中的粘性行为表明它是带有疏水基团的聚电解质。     

新型以咔唑为主链的能量转移型发光聚合物

用Suzuki偶合反应合成了一系列以咔唑为主链，与不同的芳香环和杂环化合物 共聚的新型电致发光无规共聚物．这些共聚物溶于普通的有机溶剂，发较强的荧光 ．咔唑链段为共聚物提供了很好的空穴传输和空穴注入性能．与咔唑共聚的窄能隙 单体，如蒽(ANT)、噻吩(Th)、2，1，3-苯并噻二唑(BTDZ)、2，1，3—苯并硒二唑 (BseDZ)和4，7—二噻吩—2，1，3—苯并噻二唑(DBT)在聚合物中含量小于50％时 成为陷阱中心．还观察到极为有效的分子内能量转移．由于共聚单体的能隙不同， 这些电致发光共聚物的发光范围可覆盖整个可见光谱区．研究结果表明，用咔唑作 为宽带主体，与少量低带隙单体共聚，有可能成为一种合成同时兼有优异空穴注入 特性，又能广泛调节发光颜色的新的发光聚合物体系．     

Ziegler-Natta催化乙烯/长链1-烯烃共聚合——长链1-烯烃的共聚活性

<正> 乙烯/1-烯烃共聚合是近年来活跃的研究课题之一,随1-烯烃种类不同及其在共聚物中含量的变化,共聚产物主要有橡胶弹性体(如乙丙胶)、线性低密度聚乙烯(LLDPE)等。研究结果表明,与短支链共聚单体相比,由长支链共聚单体获得的LLDPE具有更加优越的加工性能、整体韧性和抗撕裂性,由于侧基的位阻作用,长链1-烯烃参     

可聚合的光引发转移终止剂合成接枝共聚物

采用一种可聚合的光引发转移终止剂 ,2 N ,N 二乙基二硫代氨基甲酰氧基乙酸 β 甲基丙烯酰氧基乙酯 (MAEDCA) ,通过两种途径制备了含有聚甲基丙烯酸甲酯 (PMMA)和聚苯乙烯 (PSt)链段的接枝共聚物 .其一是将MAEDCA作为引发剂 ,在紫外光照射下引发MMA聚合 ,得到大分子单体 ,通过大分子单体与St的共聚合得到 .考察了所用大分子单体的分子量和浓度对共聚合的影响 .其二是将MAEDCA作为单体与MMA共聚得到侧链上含有N ,N 二乙基二硫代氨基甲酰氧基 (DC)基团的无规共聚物 ,P(MMA co MAEDCA) .在紫外光照射下 ,P(MMA co MAEDCA)作为大分子引发剂引发St聚合 ,得到P(MMA co MAEDCA) g PSt的共聚物 ,研究了接枝共聚合过程的活性自由基聚合特征     

用双官能团引发剂进行的基团转移嵌段共聚研究

本文用二种双官能团引发剂进行基团转移嵌段共聚研究,得到了一系列实测分子量和理论分子量相近、分子量分布较窄的A-B-A型嵌段共聚物。用GPC、~1H-NMR、DSC等手段对嵌段共聚物进行了表征,证明确是两相嵌段共聚丙烯酸酯。发现位阻较大的单体作为第二单体时不利于聚合。过高的催化剂用量使嵌段共聚的总转化率降低。使用极性较大的溶剂可缩短第一步聚合的诱导期,但不影响第二步聚合的诱导期,即极性较大的溶剂有利于催化剂的离解。单体浓度增大使共聚物的分子量减小,多分散性指数增大。可通过单体投料比改变共聚物的热形变温度。     

Zinc(II)-induced color-tunable fluorescence emission in the pi-conjugated polymers composed of the bipyridine unit: a way to get white-light emission

A series of fluorene and bipyridine (bpy) copolymers were synthesized, and their optical properties were investigated in the presence of zinc(II). By adjusting the bpy content in the polymer backbone, the emitting color of the polymer solution could be tuned from initial blue to green to white and violet when it interacted with zinc(II) ions. The counteranions of zinc(II) ions were also found to influence the optical properties of copolymers greatly.     

Well‐defined poly[(dimethylamimo)ethyl methacrylate]‐b‐poly(fluoroalkyl methacrylate) diblock copolymers: Effects of different fluoroalkyl groups on the solution properties

A series of well‐defined, fluorinated diblock copolymers, poly[2‐(dimethylamino)ethyl methacrylate]‐b‐poly(2,2,2‐trifluoroethyl methacrylate) (PDMA‐b‐PTFMA), poly[2‐(dimethylamino)ethyl methacrylate]‐b‐poly(2,2,3,4,4,4‐hexafluorobutyl methacrylate) (PDMA‐b‐PHFMA), and poly[2‐(dimethylamino)ethyl methacrylate]‐b‐poly(2,2,3,3,4,4,5,5‐octafluoropentyl methacrylate) (PDMA‐b‐POFMA), have been synthesized successfully via oxyanion‐initiated polymerization. Potassium benzyl alcoholate (BzO^?K⁺) was used to initiate DMA monomer to yield the first block PDMA. If not quenched, the first living chain could be subsequently used to initiate a feed F‐monomer (such as TFMA, HFMA, or OFMA) to produce diblock copolymers containing different poly(fluoroalkyl methacrylate) moieties. The composition and chemical structure of these fluorinated copolymers were confirmed by ¹H NMR, ¹⁹F NMR spectroscopy, and gel permeation chromatography (GPC) techniques. The solution behaviors of these copolymers containing (tri‐, hexa‐, or octa‐ F‐atom)FMA were investigated by the measurements of surface tension, dynamic light scattering (DLS), and UV spectrophotometer. The results indicate that these fluorinated copolymers possess relatively high surface activity, especially at neutral media. Moreover, the DLS and UV measurements showed that these fluorinated diblock copolymers possess distinct pH/temperature‐responsive properties, depending not only on the PDMA segment but also on the fluoroalkyl structure of the FMA units. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2702–2712, 2009     

Radical copolymerization of styrene and alkyl methacrylates: monomer reactivity ratios and thermal properties

Copolymers containing styrene and alkyl methacrylate (n-butyl-, n-hexyl-, or stearyl methacrylate) at different compositions have been prepared by radical copolymerization. The monomer reactivity ratios were estimated using the Finemann-Ross, the inverted FR and the Kelen-Tüdos graphical methods. Structural parameters of the copolymers were obtained calculating the dyad monomer sequence fractions. The effect of the size of the alkyl methacrylate on the copolymer structure is discussed. The glass transition temperature, T_g of the copolymers with butyl and hexyl methacrylate was examined in the frame of several theoretical equations allowing the prediction of these T_g values. The best fit was obtained using methods that take into account the monomer sequence distribution of the copolymers. The copolymers of styrene with stearyl methacrylate exhibited the characteristic melting endotherm, due to the crystallinity of the methacrylate sequences and the polystyrene glass transition temperature.     

可聚合脂质体的研究 Ⅳ含丙烯酰基的类脂分子及其与亲水性丙烯酰单体的共聚物

可聚合脂质体的研究Ⅳ含丙烯酰基的类脂分子及其与亲水性丙烯酰单体的共聚物金威曲青蓝李子臣李福绵（北京大学化学与分子工程学院北京１００８７１）关键词可聚合类脂分子，共聚合，自组织，脂质体脂质体因其优异的生物相容性做为药物释放材料而备受瞩目．一般说来，...     

Graft copolymerization. I. Grafting of hydroxyalkyl methacrylates on poly(vinyl alcohol)

New graft copolymers were synthesized by grafting hydroxyethyl methacrylate and hydroxpropyl methacrylate on poly(vinyl alcohol) in aqueous solution with Ce⁺⁴ions as initiator. The dependence of the percentage of grafting and monomer conversion on the concentration of the monomer, on the concentration of the initiator, on the total concentration of the reactants, and on temperature and duration of the reaction were investigated. Some basic properties of the graft copolymers and some preliminary permeation measurements of water vapors through films, made from these copolymers, are also reported.     

Synthesis of <Emphasis Type="Italic">N</Emphasis>-vinylpyrrolidone copolymers with 2-aminoethyl methacrylate as drug carriers

Radical copolymerization of N-vinylpyrrolidone and 2-aminoethyl methacrylate hydrochloride has been studied. Molecular and hydrodynamic characteristics of the resulting copolymers have been determined, and their structure has been confirmed. Conditions favoring conversion of these copolymers into copolymers of N-vinylpyrrolidone with 2-aminoethyl methacrylate of different composition have been elucidated. The suitability of the prepared copolymers as polymeric carriers of monofluoroquinolone ofloxacin has been demonstrated.     

Determination of copolymer composition by Raman spectroscopy

The application of laser-Raman spectroscopy to the analysis of copolymers of glycidyl methacrylate (GMA) with methyl methacrylate (MMA) and styrene is discussed. For both copolymer systems the line near 1451 cm^?1, assigned to the methylene bending mode, was found to be a useful reference. Lines characteristic of each monomer were identified. The intensities of these lines were found to be linearly related to the composition of the copolymers when normalized against the 1451 cm^?1 reference. The line near 1730 cm^?1, assigned to the carbonyl stretching mode, was also found to be a useful reference for the copolymers of methyl methacrylate and glycidyl methacrylate.     

Self-organization behavior of methacrylate-based amphiphilic di- and triblock copolymers

Amphiphilic di- and triblock copolymers having different hydrophilic-to-hydrophobic block length ratio were synthesized using ATRP. The self-assembly behavior of these AB and ABA block copolymers consisting of poly(n-butyl methacrylate) (B) and poly(2,2-(dimethylaminoethyl methacrylate) (A) was investigated using a combination of dynamic light scattering, negative-stain transmission electron microscopy, cryoelectron microscopy, and atomic force microscopy. Two populations of self-organized structures in aqueous solution, micelles and compound micelles, were detected for diblock copolymers. Triblock copolymers assembled into vesicular structures of uniform sizes. Furthermore it was found that these vesicles tended to compensate the high curvature by additional organization of the polymer chains outside of the membrane. The chain hydrophilicity of the polymers appeared to have a critical impact on the self-assembly response toward temperature change. The self-reorganization of the polymers at different temperatures is discussed.     

Ceric-initiated polymerization onto polyacrylonitrile with carbohydrate end groups. Graft versus block copolymer formation

Starch-g-polyacrylonitrile (starch-g-PAN) copolymers were prepared by ceric ammonium nitrate initiation, and the major portion of the starch in these graft copolymers was then removed by acid hydrolysis to yield PAN with oligosaccharide end groups. Although these PAN-oligosaccharide samples reacted with methyl methacrylate in the presence of ceric ammonium nitrate, the resulting products were largely graft copolymers rather than the expected PAN-poly(methyl methacrylate) (PMMA) block copolymers. The following evidence is presented for a PAN-g-PMMA structure: (i) PAN without oligosaccharide end groups also produced a copolymer with methyl methacrylate under our reaction conditions. (ii) Starch-g-PAN (51 or 37% add-on) was a less reactive substrate toward ceric-initiated polymerization than PAN with oligosaccharide end groups. (iii) Low-add-on (18%) starch-g-PAN reacted with methyl methacrylate to give a final graft copolymer in which a large percentage of PMMA was grafted to the PAN component rather than to starch.     

Cationic methacrylate copolymers containing primary and tertiary amino side groups: Controlled synthesis via RAFT polymerization,DNA condensation,and in vitro gene transfection

A versatile family of cationic methacrylate copolymers containing varying amounts of primary and tertiary amino side groups were synthesized and investigated for in vitro gene transfection. Two different types of methacrylate copolymers, poly(2‐(dimethylamino)ethyl methacrylate)/aminoethyl methacrylate [P(DMAEMA/AEMA)] and poly(2‐(dimethylamino)ethyl methacrylate)/aminohexyl methacrylate [P(DMAEMA/AHMA)], were obtained by reversible addition‐fragmentation chain transfer (RAFT) copolymerization of dimethylaminoethyl methacrylate (DMAEMA) with N‐(tert‐butoxycarbonyl)aminoethyl methacrylate (Boc‐AEMA) or N‐(tert‐butoxycarbonyl)aminohexyl methacrylate (Boc‐AHMA) followed by acid deprotection. Gel permeation chromatography (GPC) measurements revealed that Boc‐protected methacrylate copolymers had M_n in the range of 16.1–23.0 kDa and low polydispersities of 1.12–1.26. The copolymer compositions were well controlled by monomer feed ratios. Dynamic light scattering and agarose gel electrophoresis measurements demonstrated that these PDMAEMA copolymers had better DNA condensation than PDMAEMA homopolymer. The polyplexes of these copolymers revealed low cytotoxicity at an N/P ratio of 3/1. The in vitro transfection in COS‐7 cells in serum free medium demonstrated significantly enhanced (up to 24‐fold) transfection efficiencies of PDMAEMA copolymer polyplexes as compared with PDMAEMA control. In the presence of 10% serum, P(DMAEMA/AEMA) and P(DMAEMA/AHMA) displayed a high transfection activity comparable with or better than 25 kDa PEI. These results suggest that cationic methacrylate copolymers are highly promising for development of safe and efficient nonviral gene transfer agents. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2869–2877, 2010