温度/pH敏感性接枝共聚物水凝胶P(DMAEMA-g-NIPAM)的 合成及性质研究

利用大分子单体技术, 采用自由基溶液聚合合成了温度/pH敏感性聚甲基丙烯酸-N,N-二甲氨基乙酯接枝聚N-异丙基丙烯酰胺[P(DMAEMA-g-NIPAM)]水凝胶. 用红外光谱及扫描电镜对凝胶的组成及形貌进行了表征. 凝胶的去溶胀和溶胀动力学研究表明, 所合成的凝胶具有温度和pH敏感性. 与传统的聚丙烯酸系水凝胶相比, P(DMAEMA-g- NIPAM)具有相反的pH敏感性; P(DMAEMA-g-NIPAM)凝胶在55 ℃时具有较快的去溶胀速率, 随着凝胶中接枝链PNIPAM量的增加, 凝胶的去溶胀速率加快.     

氧阴离子引发甲基丙烯酸-2-(N,N-二甲氨基)乙酯聚合制备Y型大分子单体

氧阴离子聚合(Oxyanion－initiated Polymerization)是一类新型的聚合方法[‘,’‘．利用个乙烯基苦醇钾作为功能性引发剂,引发甲基丙烯酸－2－(NJ－二乙氨基)乙酯聚合,形成末端带可聚合官能团的大分子单体‘”“．氧阴离子引发剂通常难以引发甲基丙烯酸烷基酯单体聚合,但却能引发甲基丙烯酸氨基酯类单体发生聚合．由于氨基乙酯基7位上氮原子的供电子性,它能与钾离子形成螫合物,使氧阴离子的亲核性增加,从而更具有活性,引发单体聚合．氧阴离子聚合具有速度快、活性高、反应温度接近室温和产物的单分散性好等特点．尽管目前还不清楚这种反…     

甲基丙烯酸2-N,N-二甲氨基乙酯与甲基丙烯酸甲酯的氧化共聚合的机理研究

研究了CuCl/五甲基二亚乙基三胺(PMDETA)催化的甲基丙烯酸2-N,N-二甲氨基乙酯(DMAEMA)与甲基丙烯酸甲酯(MMA)在氧气存在下的氧化共聚合,通过改变单体配比、催化剂浓度和反应温度对实验条件进行研究.结果显示,在本实验中的单体配比([DMAEMA]∶[MMA]=10∶0～5∶5)、催化剂浓度([CuCl/PMDETA3]=3.1×10-5 mol/L～6×10-3 mol/L)和反应温度(30～80℃)下,聚合均可以顺利发生,而且聚合过程中单体转化率和所得聚合物的分子量都随着反应进行而增加,且分子量呈现宽分布.1H-NMR结果显示所得聚合物中含有DMAEMA和MMA的单体单元.DSC结果显示所得聚合物是一个部分相容体系.利用此方法所得的PDMAEMA进行MMA的原子转移自由基聚合(ATRP)扩链过程则证实,所得聚合物具有C—Cl末端官能团.由此可以认为,在以上过程中,O2先将CuCl氧化成[Cu(Ⅱ)Cl]+,[Cu(Ⅱ)Cl]+再将二甲胺基氧化成N—CH2.自由基,N—CH2.自由基与[Cu(Ⅱ)Cl]+构成反向ATRP体系,从而得到以C—Cl为末端的聚合物.     

Poly[2-(N,N-Dimethylamino) Ethyl Methacrylate] /Poly(Styrene-Co-Methacrylic Acid) Interpolymer Complexes

Summary: Poly[2-(N,N-dimethylamino)ethyl methacrylate] (PDMAEMA), copolymers of different compositions of styrene with 2-(N,N-dimethylamino)ethyl methacrylate (SDMAEMA) or methacrylic acid (SMA) were synthesized by free radical polymerization and characterized by several techniques. Different ternary mixtures containing proton-acceptors PDMAEMA or SDMAEMA, proton-donor copolymers SMA and a solvent (butan-2-one or THF) were prepared. The present study, that investigated several factors that affected the phase behaviors of the ternary mixtures above, confirmed that, indeed depending on the nature of solvent, densities of interacting species, amounts of efficient specific interactions that occurred between the two copolymers, interpolymer complexes of different structures were elaborated. The complexation phenomena, observed with these different systems were analyzed in solution by viscometry that confirmed these effects in monitoring the formation of interpolymer complexes. The specific interactions that occurred between pairs of polymers of each system above were qualitatively evidenced by FTIR spectroscopy from the appearance of new bands or their new redistribution. The glass transition temperature Tg of the obtained complexes of different structures determined by DSC varied differently with the weight fraction of one of the copolymers. These various Tg-compositions were analyzed using the Kwei and Brostow et al. approach recently developed. Thermal analysis of some of the elaborated complexes, examined by thermogravimetry, confirmed their improved thermal stability.     

Synthesis and biocompatibility of a novel silicone hydrogel containing phosphorylcholine

A novel poly (methyl methacrylate-co-2-methacryloyloxyethyl phosphorylcholine-co-tris(trimethylsiloxy)-3-methacryloxypropylsilane) terpolymer (PMMT) was synthesized and the anti-biofouling properties were studied in order to evaluate the potential of this silicone hydrogel to be used as contact lens material. The chemical structure was characterized by IR, ¹H-NMR and elemental analysis. Poly methyl methacrylate (PMMA) and poly (methyl methacrylate-co-tris (trimethylsiloxy)-3-methacryloxypropylsilane) (PMT) were also synthesized to compare with PMMT. Protein adsorption measurement showed that for PMMT-2 membrane (MPC: 16.6 mol%), the amount of adsorbed proteins was decreased by 75.3% and 76.8% compared with PMMA and PMT membranes, respectively. SEM pictures showed clearly that PMMT films suppressed the adhesion of platelets. Water structure in polymers was determined by differential scanning calorimetry, and PMMT-2 possessed more freezing water content than PMMT-1 (MPC: 14.5 mol%). The equilibrium water content of PMMT-2 membrane reached 55%, which might offer comfortable wear feeling, and the introduction of MPC increased the wettability of the polymer surface dramatically. Both the terpolymers PMMT-1 and PMMT-2 exhibited high transparency (relatively constant at approximately 96%) in the visible light wave range. Moreover, oxygen transmissibility (Dk/t) of the terpolymers met the requirement for a lens to be worn safely overnight. It could be concluded that the novel silicone hydrogel containing MPC unit was an effective candidate material for making biomaterials, particularly for contact lenses.     

磷酰胆碱基pH敏感性ABA型嵌段共聚物的合成与胶束化

采用氯化亚铜/2,2-联二吡啶催化体系, 2,5-二溴己二酸二乙酯为引发剂, 甲醇为溶剂运用希莱克技术, 利用原子转移自由基聚合(ATRP)方法合成了ABA型三嵌段共聚物PDEAEMA-b-PMPC-b-PDEAEMA. ¹H NMR和GPC(凝胶渗透色谱)对聚合物组成、结构及分子量进行了表征, 利用透光率、粘度测定研究了嵌段共聚物溶液的pH敏感性, 利用表面张力测定、荧光探针和透射电镜研究了嵌段共聚物胶束化作用, 确定了共聚物水溶液的临界胶束浓度(CMC). 结果表明所合成的ABA型三嵌段共聚物水溶液具有pH敏感性, 其临界相变pH 7～7.5. 调节溶液pH值可实现嵌段共聚物胶束化形成“花状”胶束, 并测定了其临界胶束浓度.     

Dynamic Surface Elasticity of Polyelectrolyte/Surfactant Adsorption Films at the Air/Water Interface: Carboxylmethylchitosan and Cetyltrimethylammonium Bromide

The dynamic surface elasticity of the solution of carboxymethylchitosan (CMCH) and cetyltrimethylammonium bromide (C₁₆TAB) was measured as a function of the surfactant concentration and the surface age by the oscillating drop method. The results showed that the surface layer of the CMCH/C₁₆TAB solution transformed from loose to structured with the increase in the surfactant concentration. The surface elasticity versus the surface pressure curve during the adsorption showed different features at different surfactant concentration ranges, which was connected with the structural transformation of the surface layer. Our results show that the measurement of dynamic surface dilational properties is a powerful tool for studying the surface kinetics, which is helpful for dealing non-equilibrium systems in industry.     

Adsorption of protein on the surface of thermosensitive poly(methyl methacrylate) microspheres modified with the N-(2-hydroxypropyl)methacrylamide and 2-(methacryloyloxy)ethyl phosphorylcholine moieties

A series of microspheres composed of methyl methacrylate (MMA) and N-(2-hydroxypropyl)methacrylamide (HPMA), and/or 2-(methacryloyloxy)ethyl phosphorylcholine (MPC), i.e., binary copolymer microspheres [poly(HPMA-co-MMA)_KPS and poly(HPMA-co-MMA)_ABIP] and ternary ones [poly(HPMA/MPC-co-MMA)_KPS and poly(HPMA/MPC-co-MMA)_ABIP], were prepared by emulsifier-free emulsion copolymerization using potassium peroxodisulfate (KPS) or 2,2′-azobis[2-(imidazolin-2-yl)propane] dihydrochloride (ABIP) as initiators. The decrease in ζ-potential of the polymer microspheres is caused by the addition of the HPMA and/or MPC moieties. Equilibrium water content of poly(HPMA-co-MMA)_ABIP showed a remarkable swelling change with a change in response to temperature: the hydrated conformation at 28°C and the dehydrated one at above 40°C. The adsorption of protein on the polymer microspheres also changed in response to change in temperature. The ternary polymer microspheres effectively suppressed the adsorption both of Alb and Glo, less than binary ones. A series of polymer microspheres are expected to apply as a novel drug carrier with both thermosensitive and nonthrombogenic functions. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 3349–3357, 1997     

N-(2-溴乙基)咔唑与N-乙烯基咔唑的气相HeI紫外光电子能谱与电子结构研究

首次报道了N-(2-澳乙基)咔唑和N-乙烯基咏唑的气相Hel紫外光电子能谱(UPS),借助于Gaussian 94采用RHF/6-3lG基组优化几何构型,并用RHF/6-31G基组计算分子轨道及能级.在对咔唑和N-烷基咔唑系列分子UPS电离能变化规律研究的基础上,对这2个分子的UPS谱带给予指认,并讨论其电子结构.结果表明N-(2-溴乙基)咔唑的UPS谱与N-烷基咔唑的不同之处是在10.295,10.540Ve处出现2个Br原子的孤对轨道;N-乙烯基咔唑的UPS谱带与咔唑的相比,电离能变化的特殊性说明乙烯基与咔唑环共平面.     

Conformation and Aggregation Behavior of Polyelectrolyte with Primary Amino Pendant Groups in Water or THF/Water Binary Solvent Mixture and Their Effect on the Morphology of AOT Vesicles in Aqueous Media

Cationic polyelectrolyte with primary amine pendant groups, poly (4-vinyl benzyl amine hydrochloride salt) (poly (4-VBAHS)), was characterized by static light scattering. Using light scattering measurement, the conformation transition of poly (4-VBAHS) chains in pure water, and THF/H₂O (v/v: 1/3) binary solvent mixture was discussed. Concentration-dependent multiple morphologies including interpenetrating networks, tubular micelles, branched micelles, hexagonal phases, vesicles, and needle crystals were observed by TEM. In addition, effect of poly (4-VBAHS) on the morphology, stability, and critical vesicle/micelle concentration of anionic surfactant sodium bis (2-ethylhexyl) sulfosucciante vesicles were detected using dynamic light scattering, zeta potential, surface tension, and transmission measurements.     

HA/PDM自组装复合胶体粒子及其乳化性能

以阴离子天然大分子透明质酸(HA)和阳离子单体甲基丙烯酸二甲氨基乙酯(DM)组成带相反电荷的聚合物/单体复合体系, DM通过水相原位聚合可制备荷正电的聚甲基丙烯酸二甲氨基乙酯(PDM), PDM与HA间的静电作用可诱导两者在水溶液中进行自组装, 得到HA/PDM复合胶体粒子. 用傅里叶变换红外(FTIR)光谱仪对HA/PDM复合物结构进行了表征. 用动态激光光散射(DLS)研究了HA与PDM复合体系在水溶液中的自组装行为, 并表征了反应时间对HA/PDM复合胶体粒子粒径的影响. 利用透射电镜(TEM)表征了胶体粒子的形貌. 考察了溶液pH 对胶体粒子粒径及zeta 电位的影响, 并对胶体粒子的乳化性能进行初步探索. 结果表明:DM单体聚合前, 无HA/DM复合物聚集体形成; 而随着DM的逐步聚合, HA与PDM可通过静电作用逐渐组装形成球状HA/PDM复合胶体粒子, 其粒径随反应时间延长逐渐减小并趋于稳定. 同时, 该复合胶体粒子具有pH敏感性和乳化性, 乳化性能较纯HA和PDM有较大提高.     

折叠型双银配合物电子结构与相关性质

在密度泛函B3LYP/LanL2DZ的水平上,对具有π-π弱相互作用调控的折叠型银配合物Ag₂(MPTQ)₂²⁺进行计算研究。探讨该配合物的电子结构、成键特征、π-π弱相互作用机理、电荷布居及其相关性质。计算结果表明,Ag…Ag之间存在弱的直接相互作用,HOMO主要布居在配体中芳香环的σ-p轨道、S的σ-p轨道及与S相连的C12的S轨道上,LUMO主要布居在配体中芳香环的π^*-p轨道上,基态电子光谱主要是配体中的n→π^*跃迁产生的电荷转移光谱。论文还讨论了分子间π-π弱相互作用的本质及活性部位等。计算结果能较好地解释实验现象与规律。     

Solution properties of well-defined 2-(dimethylamino)ethyl methacrylate-based (co)polymers: A viscometric approach

Well-defined poly(2-(dimethylamino)ethyl methacrylate)-based (co)polymers with various molar masses were synthesized by atom transfer radical polymerization (ATRP) using CuBr ligated with 1,1,4,7,10,10-hexamethyltriethylenetetramine (HMTETA) as catalyst, and ethyl 2-bromoisobutyrate (EBiB) or α-methyl, ω-(2-bromoisobutyrate) poly(ethylene glycol) (mPEG_x-BiB) as (macro)initiator. The solution properties of these (co)polymers were investigated by viscometry either in pure water or in concentrated buffer solutions. It comes out that reduced viscosity in pure water is strongly affected by the molar mass of poly(2-(dimethylamino)ethyl methacrylate) block but also by the quaternization degree of tertiary amino groups. In fact, a polyelectrolyte effect can only be detected when the charge density per macromolecule reaches a critical value either in terms of molar mass or quaternization degree. Fitting of viscometry data according to either Huggins or Fuoss and Fedors equation also allows calculating the intrinsic viscosity and approaching the overlap concentration.     

Temperature- and pH-responsive behaviour of poly(2-(2-methoxyethoxy)ethyl methacrylate-co-N,N-dimethylaminoethyl methacrylate) hydrogels

Hydrogels with pH/temperature responsiveness and high water uptake have been synthesized by the free radical polymerization of 2-(2-methoxyethoxy)ethyl methacrylate (MEO₂MA) with N,N-dimethylaminoethyl methacrylate (DMAEMA) in a low proportion. The amphiphilic character of the biocompatible MEO₂MA provides thermo-sensitivity at low temperature. On the other hand, DMAEMA units incorporate ionisable amino groups and hydrophobic moieties, leading by themselves to a dual pH and thermo-sensitive system. Therefore, the combination of both monomers yields an interesting system with tuneable pH/temperature responsiveness and swelling capacity, which depends on composition and ionic strength. Thus, the volume transition temperature (VTT) is suppressed at low pH due to the basic character of DMAEMA. However, at basic pH, where amino groups are not charged, lower swelling capacities and narrow thermal volume transitions were obtained. At neutral pH, higher modulation of both the swelling achieved and VTT was observed.     

Preparation and characterization of antibacterial microporous membranes fabricated by poly(AMS-co-DMAEMA) grafted polypropylene via melt-stretching method

Functional polypropylene (PP) is prepared by graft poly(AMS-co-DMAEMA) onto PP chains through melt blending, and then microporous membranes of functional PP are made by casting and stretching, and finally the polycation microporous membranes are obtained via quaternization. The obtained microporous membranes show good hydrophilicity and antibacterial properties.     

The synthesis and solution behaviors of novel amphiphilic block copolymers based on d-galactopyranose and 2-(dimethylamino)ethyl methacrylate

A series of novel stimuli-responsive AB, ABA, and BAB type block copolymers based on 6-O-methacryloyl-1,2:3,4-di-O-isopropylidene-d-galactopyranose (MAIpGP:A block) and 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA: B block) were synthesized via ATRP techniques using ethyl 2-bromoisobutyrate (EBiB) as monofunctional ATRP initiator in the case of diblock copolymer and diethyl meso-2,5-dibromoadipate (DEDBA) as bifunctional ATRP initiator in the case of triblock copolymers. The PMAIpGP blocks of the AB, ABA, and BAB type linear block copolymers were converted to water soluble PMAGP blocks via deprotection process under mild acidic conditions. Both proton NMR and DLS studies demonstrated that block copolymers were temperature-sensitive, whereby the lower critical solution temperature (LCST) of polymers varied with the polymerization degrees of comonomers in the block copolymers. LCST was determined to be between ∼35 °C and 55 °C depending on the type and the comonomer compositions of the block copolymers. It was observed that an increase on the percentage of hydrophilic PMAGP block in block copolymer caused an increase on the LCST value as expected.     

Microwave-Assisted Synthesis and Characterization of Poly(2-(dimethylamino)ethyl methacrylate) Grafted Gellan Gum

Poly(2-(dimethylamino)ethylmethacrylate) was grafted on gellan gum (GG) in aqueous medium under microwave irradiation using ammonium persulfate and N,N,N′N′-tetramethylethylenediamine as the initiation system. Grafted copolymers were characterized by FT-IR, TGA, and SEM techniques. The influence of microwave power, exposure time, and composition of the reaction mixture on extent of grafting was studied. Conditions for obtaining the highest degree of grafting were optimized. The rate of grafting was determined from weight measurements. The overall activation energy for grafting is found to be 31.2 kJ/mol, indicating the occurrence of the grafting process with absorption of low thermal energy.     

3-(2-氧代环烷基)丙酸与(R)-2-硫代四氢噻唑-4-羧酸乙酯的反应

３－（２－氧代环烷基）丙酸与（Ｒ）－２－硫代四氢噻唑－４－羧酸乙酯的反应李叶芝,田颜清,黄化民（吉林大学化学,长春,１３００２３）关键词（Ｒ）－２－硫代四氢噻唑－４－羧酸乙酯,Ｎ－３－（２－氧代环烷基）丙酰－２－硫代四氢噻唑－４－羧酸乙酯,环合反应,...