New Polymers Derived from Poly(Methylphenylphosphazene)

Abstract

The sequential treatment of [Me(Ph)PN]_n with n-BuLi and electrophiles such as substituted chlorosilanes, aldehydes and ketones, and carbon dioxide results in new functionalized polyphosphazenes. Graft copolymers have also been prepared by using the anionic polymer intermediate to initiate anionic addition polymerization of styrene, CH₂=C(Ph)H, and ring opening polymerization of hexamethylcyclotrisiloxane, [Me₂SiO]₃.     

Isocyanate-Terminated Poly(ethylene Oxide)

Isocyanate-terminated polyethylene oxide (PEO) was prepared by reaction of hydroxyl-terminated PEO of different molecular weights and toluene diisocyanate (TDI), at a molar ratio of 1:2. Reaction was carried out with and without catalyst (dibutyltin dilaurate). When catalyst was used, some chain extension accompanied the endcapping reaction. When endcapping reaction was carried out without catalyst, chain extension was minimal as determined from endgroup analysis and viscosity measurements. It was also found that secondary reactions of the terminal isocyanate groups led to further increase in solution viscosity after completion of the endcapping reaction.     

Studies on Ultrasonic Degradation and Block Copolymerization of Hydroxyethylcellulose and Poly(ethylene Oxide)

The ultrasonic degradation of hydroxyethylcellulose (HEC) and poly (ethylene oxide) (PEO) in aqueous solution, and the copolymerization of HEC with PEO were studied. The structure of the copolymer was identified by DTA, IR, MS, x-ray diffraction, and polarizing microscopy. The copolymer prepared is mainly block. The copolymer formed amounts to 55.07% by irradiating 0.5% HEC/PEO aqueous solution for a period of 10 min at 25°C and 18.2 kHz with 2.5 A input current on a reversed main circuit.     

聚L-丙氨酸-聚乙二醇嵌段共聚物的胶束化行为研究

以氨基聚乙二醇单甲醚(MPEG-NH₂)为大分子引发剂, 采用开环聚合方法合成了聚L-丙氨酸-聚乙二醇嵌段共聚物(PAME), 并对其结构进行了表征; 用圆二色谱(CD)研究了嵌段共聚物在水溶液中的二级结构, 用芘荧光探针技术研究了共聚物胶束的形成及其临界胶束浓度(CMC), 利用动态光散射(DLS)和透射电镜(TEM)研究了胶束的粒径分布和形态. 结果表明, 在水溶液中共聚物链以α-螺旋构象形式存在, 在一定条件下嵌段共聚物能够形成球形的稳定胶束, PAME-1形成胶束的CMC为1.99×10^-5 mol/L, CMC值受共聚物中聚L-丙氨酸(PLA)链段含量的影响.     

The Synthesis of Poly(ethylene oxide)-Block-Polybutylacrylate

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甲氧基聚乙二醇-b-聚L-半胱氨酸两亲性嵌段共聚物的合成与表征

首先以聚乙二醇单甲醚(mPEG-OH)为单体,采用经典的盖布瑞尔伯胺合成法合成了端氨基聚乙二醇单甲醚(mPEG-NH_2);然后以mPEG-NH_2为引发剂,S-苄基L-半胱氨酸N-羧酸内酸酐(BCys-NCA)为原料,通过N-羧酸内酸酐(NCA)开环聚合反应和液氨/钠处理脱除侧链上的保护基团,合成了两亲性嵌段共聚物甲氧基聚乙二醇-b-聚L-半胱氨酸(mPEG-b-PCys)。采用傅里叶变换红外光谱、核磁共振氢谱对聚合物的结构和组成进行了表征。结果表明:成功制备了侧链具有还原性巯基的两亲性嵌段共聚物mPEG-b-PCys,并且其聚合度可控性良好。     

聚乙二醇单甲醚-聚L-赖氨酸嵌段共聚物的合成及其表征

以L-赖氨酸为原料,先制备Nε-苄氧羰基-L-赖氨酸,光气法合成Nε-苄氧羰基-L-赖氨酸-N-羧酸酐[Lys-(Z)-NCA]。以聚乙二醇单甲醚(MPEG)为原料,制备了端氨基聚乙二醇单甲醚(MPEG-NH2),并以此为大分子引发剂,在氯仿中引发Lys-(Z)-NCA开环聚合,经无水溴化氢脱苄,合成不同组成和分子量的聚乙二醇单甲醚-聚L-赖氨酸嵌段共聚物。用IR1、H-NMR、GPC、DSC等对共聚物结构进行了表征。结果表明:MPEG-NH2引发Lys-(Z)-NCA开环聚合得到的是嵌段共聚物,通过1H-NMR谱计算得到了共聚物MPEG-PLL-1、MPEG-PLL-2、MPEG-PLL-3、MPEG-PLL-4中PLL链段的摩尔分数分别为0.553、0.795、0.848、0.861,共聚物数均分子量(Mn)分别为2.3×104、6.1×104、8.6×104、9.5×104。     

Protein and Dye Adsorption on Poly(ethylene terephthalate) Nucleopore Membranes Modified with Polymers

Adsorption of basic, neutral, and acidic proteins on poly(ethylene terephthalate) nucleopore membranes was studied as a function of solution pH. Higher adsorption values were observed for basic and neutral proteins and lower, for acidic proteins. The value of pH corresponding to maximal adsorption was somewhat lower than the isoelectric points of proteins, thus suggesting that the adsorption was governed by a combination of ionic and hydrophobic interactions between proteins and the membrane surface. Proteins were adsorbed in an associated form. Membrane surface was modified with poly(ethylene imine) and poly(ethylene glycol). Combined modification of the membranes with these polymers was found to substantially decrease the adsorption of basic and neutral proteins, as well as basic dye and to slightly increase the adsorption of acidic proteins. The modifying coating had a high hydrolytic stability.     

Interactions between Poly(ethylene Oxide) and Sodium Dodecyl Sulfate in Elongational Flows

This work investigates the elongational flow of aqueous solutions of mixtures of a high-molecular-weight poly(ethylene oxide) (PEO) and sodium dodecyl sulfate (SDS). The formation of micellar aggregates of SDS along the PEO chain results in an increase in the strength of the extension thickening of the PEO solutions. This is especially pronounced under conditions in which the PEO molecules form transient entanglements in the flow field. The minimum PEO concentration required to form intermolecular entanglements is substantially reduced in the presence of micellar aggregates. This effect becomes quantitatively less important in solutions with NaCl, which suggests PEO coil contraction due to electrostatic screening of micellar aggregates. However, once extension thickening starts in the presence of NaCl, the growth of pressure drop is more abrupt than without salt, which suggests stronger interactions between PEO coils with attached aggregates. The critical aggregation concentrations of PEO/SDS and PEO/SDS/NaCl solutions agree with those reported in the literature, which were obtained by means of different experimental techniques. However, the saturation of the surfactant effect is attained at lower surfactant concentrations than the polymer saturation point previously reported. This might reflect a low sensitivity of the extension thickening effect to the amount of surfactant bound to the polymerchain as the saturation point is approached. Copyright 2001 Academic Press.     

Fluorocarbon End-functionalized Polymers from Poly(arylether) Dendritic Initiators

Fréchet-type poly(arylether) first and second generation (G1 and G2 respectively) dendrons were prepared from 1-(bromomethyl)-3,5-bis(trifluoromethyl)benzene. The latter and the brominated versions of the two dendrons were successfully employed in the copper mediated living radical polymerization (LRP) of styrene-d₈ giving polymers of predictable molecular weights and narrow polydispersities. Contact angle measurements and ion beam analysis were used to explore the adsorption of these materials to the air-polymer surface in blended films with unfunctionalized hydrogenous polystyrene. Although contact angle analysis indicated only modest changes in the hydrophobicity and lipophobicity of the surface, ion beam analysis clearly showed the formation of an excess layer of dendron functionalized polymer at the exposed surface that increased with increasing fluorine content.     

聚(对苯二甲酸丁二醇酯-co-对苯二甲酸环己烷二甲醇酯)-b-聚乙二醇嵌段共聚物的合成与表征

用熔融缩聚法合成了一系列聚(对苯二甲酸丁二醇酯-co-对苯二甲酸环己烷二甲醇酯)-b-聚乙二醇嵌段共聚物(PBCG),用NMR,GPC,DSC,TGA及力学性能测试等方法表征了材料的结构与性能.GPC分析显示,共聚物分子量均具有较为对称的单峰分布,多分散性指数低于1.70.¹³CNMR谱结果表明,随PCT摩尔分数(x_PCT)从10%增至60%,PBT平均序列长度由4.02降到1.41;而PCT平均序列长度则由1.17升至2.50,二者呈无规分布.受硬段平均序列长度及结晶能力影响,硬段熔点及结晶度在x_PCT为20%～30%处均达到最小值,可能是硬段间形成共晶所致.TGA分析显示,引入芳香族聚酯组分PCT确可提高材料的热稳定性.力学性能测试说明,降低结晶度有利于提高材料的断裂延伸率,相反,则有助于增强弹性模量,断裂强度及屈服强度.     

Facile Synthesis of Polyhydroxylated Polybutadiene Derived from Hydroxyl-Terminated Polybutadiene via Thiol-Ene Click Reaction

Polyhydroxylated polybutadiene (PHPB) was synthesized via a thiol-ene click reaction between hydroxyl-terminated polybutadiene (HTPB) and 2-mercaptoethanol (ME) with 2,2’-azoisobutyronitrile (AIBN) as initiator. Effects of AIBN content, reaction time and temperature on the click reaction were investigated by determining hydroxyl value of the PHPB. The PHPB was characterized by FT-IR, ¹H-NMR, ¹³C-NMR and GPC. Relative reactivity of three types of C?C double bonds (1,2-vinyl, 1,4-cis and 1,4-trans units) in the HTPB reacting with the ME was discussed. The results showed that the optimal reaction conditions were that the AIBN content, reaction time and temperature were 2.0 wt%, 180 min and 70°C, respectively. Under these conditions, the hydroxyl value of the PHPB was 3.12 mmol·g^?1 when the HTPB/ME mass ratio was 10:2. All three types of C?C double bonds in the HTPB could react with the ME and the reactivity order was: 1,2-vinyl unit > 1,4-cis unit > 1,4-trans unit.     

Rheology and Drug Release Properties of Bioresorbable Hydrogels Prepared from Polylactide/Poly(ethylene glycol) Block Copolymers

Ring-opening polymerization of L(D)-lactide was realized in the presence of poly(ethylene glycol) (PEG), yielding PLLA/PEG and PDLA/PEG block copolymers. Bioresorbable hydrogels were prepared from aqueous solutions containing both copolymers due to interactions and stereocomplexation between PLLA and PDLA blocks. The rheological properties of the hydrogels were investigated under various conditions by changing copolymer concentration, temperature, time and frequency. The hydrogels constitute a dynamic and evolutive system because of continuous formation/destruction of crosslinks and degradation. Drug release studies were performed on hydrogel systems containing bovine serum albumin (BSA). The release profiles appear almost constant with little burst effect. The release rate depends not only on gelation conditions such as time and temperature, but also on factors such as drug load, as well as molar mass and concentration of the copolymers.     

环氧乙烷和环氧丙烷共聚物及其盐复合物的结晶与熔融

环氧乙烷和环氧丙烷共聚物及其盐复合物的结晶与熔融齐力，林云青，陈东霖（中国科学院长春应用化学研究所长春１３００２２）关键词环氧乙烷环氧丙烷共聚物，高分子固体电解质，结晶，熔融聚环氧乙烷（ＰＥＯ）及其盐复合物等￣［１，２］是一类高分子固体电解质，但ＰＥ...     

Sol-Gel Derived Macroporous Titania Films Prepared from the System Containing Poly(ethylene glycol) Together with Long-Chain Alcohols

The effect of alcohol-type on macroscopic morphology has been examined for the macroporous titania (TIO₂) films prepared by a sol-gel dip-coating method from the system containing poly(ethylene glycol) (PEG) and alcohols having larger alkyl groups than ethanol. The phase separation is enhanced by decreasing the compatibility between the solvent mixture and PEG as long as the polycondensation rate does not increase greatly. In the 1-butanol system, macroporous morphology appears clearly even at higher relative humidity as 70% RH due to the slower polycondensation. In contrast, the macroscopic domain formation is completely suppressed by the rapid polycondensation in the 2-propanol system.     

Micellization and Adsorption Parameters of Poly(Propylene Oxide)/Poly(Ethylene Glycol) Block and Graft Copolymers in Aqueous Medium

This work aims to measure the adsorption and micellization parameters of new water soluble nonionic amphiphilic block and graft copolymers based on hydrophilic poly (ethylene glycol) (PEG) and hydrophobic poly (propylene oxide) (PPO) at ambient temperature and normal atmospheric pressure. The chemical composition and molecular weights of the prepared copolymers were determined from ¹H NMR analyses. The surface properties of the prepared surfactants were determined by measuring the surface tension at different temperatures. The surface tension, critical micelle concentration, and surface activities were determined at different temperatures. Surface parameters such as surface excess concentration, the area per molecule at interface and the effectiveness of surface tension reduction were determined from the adsorption isotherms of the prepared surfactants. Some thermodynamic data for the adsorption and micellization process were calculated and are discussed.     

聚乙二醇-聚乳酸共聚物胶束溶液的冷冻干燥及胶束体外释药动力学研究

合成了一系列亲水、疏水链段质量比例不同的聚乙二醇-聚乳酸(PEG-PLA)嵌段共聚物胶束, 并以两性霉素B为模型药物制备了载药胶束. 为获得稳定性良好的、可长期储存的载药胶束剂型, 对胶束进行了冷冻干燥. 使用不同浓度的糖类(包括甘露糖、海藻糖、葡萄糖)、泊洛沙姆188 (Pluronic F68)、聚乙二醇作为冻干保护剂, 以冻干产品的重分散性、冻干前后胶束的粒径及多分散性为指标评价各种保护剂的保护效果. 结果发现, 当嵌段聚合物中聚乳酸链段的质量百分比小于或等于聚乙二醇时, 糖类、Pluronic F68和PEG均可以起到有效的冻干保护作用; 而对于聚乳酸链段质量比例较大的共聚物胶束, 只有PEG和Pluronic F68能够起到较好的冻干保护作用. 对载药胶束体外释放研究表明, 聚合物胶束的体外释放缓慢, 符合一级动力学特征.     

超声辐照下PEO与NaMAA嵌段共聚反应的研究

本文研究了在超声波辐照下聚氧化乙烯与甲基丙烯酸钠在水溶液中的嵌段共聚反应和共聚物结构。共聚反应按自由基聚合机理进行。反应动力学方程可用-(d[M]/(dt))=k[R·]^(1/6)[M]表示。随辐照时间或单体浓度的增加,共聚物产率和共聚物中NaMAA含量增大。将1％PEO-105％NaMAA水溶液在频率21.5kHz、阴极电流0.7A的超声强度下辐照15分钟,共聚物的产率为24.0％。用IR、MS、NMR、DSC、TEM等分析了共聚物的化学结构和聚集态结构,表明所得共聚产物为嵌段共聚物。