PE-b-PEO嵌段共聚物的合成

首先以正丁基锂为引发剂(n-BuLi),三异丁基铝为添加剂,通过单体活化顺序负离子聚合由丁二烯和环氧乙烷合成聚丁二烯-b-聚环氧乙烷嵌段共聚物,然后采用对甲苯磺酰肼进行常压加氢反应,得到一系列窄相对分子质量分布的聚乙烯-b-聚环氧乙烷嵌段共聚物。考察了三异丁基铝用量对环氧乙烷聚合动力学的影响,并表征了聚合产物的结构组成。结果表明:当n(Al):n(n-BuLi)较小时(6),环氧乙烷的动力学曲线中存在明显的诱导期;随着n(Al):n(n-BuLi)增大(10,14),诱导期缩短,聚合反应速率加快。所制聚合物具有预定的结构,且相对分子质量可控。     

P2VP-b-PS-b-PI三嵌段共聚物的RAFT合成及表征

以S-十二烷基-S’-(α,α’-二甲基-α’’-乙酸)-三硫代碳酸酯(DDMAT)为链转移剂,通过可逆加成-断裂链转移自由基聚合(RAFT)方法制备了窄分布的聚2-乙烯基吡啶。再以该聚合物为大分子链转移剂,引发苯乙烯的RAFT聚合,得到聚2-乙烯基吡啶-b-聚苯乙烯(P2VP-b-PS)的两嵌段共聚物。以P2VP-b-PS为RAFT试剂,合成聚2-乙烯基吡啶-b-聚苯乙烯-b-聚异戊二烯(P2VP-b-PS-b-PI)的三嵌段共聚物。运用1H NMR、IR和凝胶渗透色谱(GPC)等技术对产物的结构和分子量及分子量分布进行表征,采用原子力显微镜(AFM)观察三嵌段共聚物薄膜的微相分离结构。结果表明,所得三嵌段共聚物P2VP72-b-PS136-b-PI300分子量分布较窄(PDI=1.69),合成过程具有活性/可控聚合特征,聚合物薄膜经溶剂退火处理后出现了明显的微观相分离结构。     

嵌段共聚物偶联剂对玻璃纤维增强不饱和聚酯的界面改性作用

采用原子转移自由基聚合(ATRP)方法合成的聚苯乙烯-b-聚丙烯酸丁酯-b-聚γ-甲基丙烯酰氧丙基三甲氧基硅烷(PS-b-PnBA-b-PMPS)嵌段共聚物偶联剂处理玻璃纤维,研究了共聚物偶联剂对玻璃纤维增强不饱和聚酯力学性能的影响.结果表明:嵌段共聚物偶联剂能有效改善复合材料的强度、模量及韧性,适当增大共聚物中聚苯乙烯嵌段的链长,有利于复合材料的弯曲强度和弯曲模量的提高;复合材料的冲击强度则随着PnBA嵌段链长的增长而提高,但过长的PnBA链长会导致弯曲强度及模量的下降.当PnBA聚合度为50时,可获得强度、模量及韧性均较高的复合材料.     

两亲性苯乙烯嵌段共聚物的合成及结构表征

以α,α'-二甲基-α-乙酸-三硫代碳酸酯(BDATC)为链转移剂,采用可逆-加成-断裂链转移(RAFT)自由基聚合方法合成了末端带有—COOH官能团的两亲性嵌段共聚物聚苯乙烯-b-聚甲基丙烯酸聚乙二醇单甲醚-b-聚苯乙烯(PSt-b-POEOMA-b-PSt),这种含有亲水性端基的嵌段共聚物可以自组装成核-壳结构的纳米微粒,用于载药高分子的模板研究。利用FTIR、1HNMR、GPC对产物结构进行表征,用热失重(TG)和差示扫描量热(DSC)的方法研究了3种不同比例的嵌段共聚物的热性能。实验结果表明,通过RAFT聚合方法得到了所设计的嵌段共聚物,相对分子质量(简称分子量,下同)分布1.35左右;嵌段共聚物的热稳定性较好,通过玻璃化转变温度(Tg)的变化推测出嵌段共聚物中两种嵌段比例对两嵌段相容性的影响。     

一种水溶性含苯硼酸二嵌段共聚物的制备及表征

本研究首先通过原子转移自由基聚合(ATRP)方法制备了二嵌段共聚物,聚乙二醇-b-聚(甲基丙烯-2-甲氨基乙酯)(PEG-b-PDMAEMA),再通过对PEG-b-PDMAEMA的季胺化,制备了苯硼酸化的聚乙二醇-b-聚(甲基丙烯-2-甲氨基乙酯)(PEG-b-PBDMAEMA)。通过~1H-NMR谱图和GPC对PEG-b-PBDMAEMA进行结构表征,并利用DLS研究PEG-b-PBDMAEMA的水溶性。结果表明以季胺化为后改性手段,成功制备出水溶性良好的含苯硼酸二嵌段共聚物。     

侧链带有手性基团的聚半胱氨酸-b-聚环氧丙烷-b-聚半胱氨酸嵌段共聚物的合成

首次合成了侧链带有手性基团的聚半胱氨酸-b-聚环氧丙烷-b-聚半胱氨酸嵌段共聚物。首先炔丙基溴和L-半胱氨酸反应,合成了S-炔丙基-L-半胱氨酸,产物与三光气反应,合成S-炔丙基-N-羧基-L-半胱氨酸-环内酸酐(NCA);然后用大分子引发剂双端氨基聚环氧丙烷引发S-炔丙基-N-羧基-L-半胱氨酸-环内酸酐(NCA)开环聚合,制得了聚环氧丙烷-聚(S-炔丙基-L-半胱氨酸)嵌段共聚物;最后由N3-L-亮氨酸与共聚物侧链上的炔键发生Click反应,制得了侧链连有手性基团的嵌段共聚物。用1H NMR、IR、GPC和元素分析等方法对所得嵌段聚合物结构进行了表征。     

聚对苯二甲酸乙二醇酯成核剂及其制备方法

复旦大学研究人员开发出一种聚对苯二甲酸乙二醇酯的成核剂及其制备方法。该方法以聚苯乙烯-b-聚（苯乙烯-alt-马来酸酐）两嵌段共聚物为原料,经过水解、盐化以及提纯制得聚苯乙烯-b-聚（苯乙烯-alt-马来酸酐）两嵌段共聚物的离聚物。聚苯乙烯嵌段可以在PET熔体中形成微相分离,     

两亲性聚(γ-苄基-L-谷氨酸酯)-b-聚丙烯酸的合成

以聚(γ-苄基-L-谷氨酸酯)为原料制备聚肽型溴代异丁酰化聚(γ-苄基-L-谷氨酸)大分子引发剂,通过引发丙烯酸叔丁酯的原子转移自由基聚合,然后水解制备了两亲性聚(γ-苄基-L-谷氨酸酯)-b-聚丙烯酸。用核磁共振和凝胶渗透色谱法对该嵌段共聚物的结构进行了表征,并用透射电子显微镜研究了嵌段共聚物在氯化钠水溶液中的聚集状态。结果表明,聚丙烯酸链段的引入,使聚合物在氯化钠水溶液中形成囊泡状胶束。     

基于偏氯乙烯嵌段共聚物的多级多孔炭的制备

采用可逆加成-断裂链转移（RAFT）活性自由基聚合制备了聚苯乙烯-b-聚偏氯乙烯-b-聚苯乙烯嵌段共聚物（PS-b-PVDC-b-PS）,以此嵌段共聚物为碳前驱体,直接碳化制备微孔-中孔复合多级多孔炭。采用凝胶渗透色谱仪和核磁共振仪表征了嵌段共聚物结构,表明通过RAFT聚合可制得分子量较高（M_n^GPC >6000 g·mol^-1）和分子量分布较窄（PDI<1.5）的PS-b-PVDC-b-PS。采用热重分析表征嵌段共聚物热解特性,采用扫描电镜、N₂吸脱附表征多孔炭形貌和孔隙结构。结果表明嵌段共聚物同时具有PVDC和PS链段的热失重峰,PS链段可完全热解而具有形成中孔的模板作用,PVDC链段热降解形成含微孔的炭骨架,最终形成兼有微孔和中孔的多级多孔炭;随着PS嵌段含量的增加,嵌段共聚物的成炭率逐渐降低,孔隙尺寸逐渐增大;当PS/PVDC聚合度比为4.3时,多孔炭的比表面积、中孔率和平均孔径达到最大,分别为839 m²·g^-1、54%和2.02 nm。     

pH响应型六臂星形共聚物的制备及药物控释研究

通过开环聚合(ROP)和原子转移自由基聚合(ATRP)设计合成了两种两亲性六臂星形共聚物聚己内酯-b-聚甲基丙烯酸羟基乙酯(6sPCL-b-PHMEA)和聚己内酯-b-聚甲基丙烯酸二乙基氨基乙酯-b-聚甲基丙烯酸羟基乙酯(6s PCL-b-PDEAM-b-PHEMA)。采用傅立叶变换红外光谱(FT-IR)和动态光散射技术(DLS)研究了共聚物的结构和胶束的粒径,并以阿霉素(DOX)为模型药物考察了两种胶束的药物控释动力学。结果表明:两种胶束均具有合适的粒径,可作为DOX载体,6sPCL-b-PHEMA和6s PCL-b-PDEAM-b-PHEMA胶束的载药量分别为11.56%和14.23%。体外释药实验结果表明,与二嵌段星形共聚物相比,三嵌段星形共聚物具有显著的p H敏感性,pH值从7.4降至2.2时,胶束中DOX的累积释药率显著增大。这种p H响应的六臂星形共聚物具有潜在的抗癌药物控释应用前景。     

温敏聚合物及其水凝胶的研究进展

综述了温度敏感聚合物及其水凝胶最近几年的研究进展,讨论了该聚合物的组成、主链结构、分子量以及聚合方法对水凝胶和温敏聚合物的影响。随着聚合物的主链结构和侧链分子量的改变,聚合物的低临界溶解温度（LCST）可以在较宽的范围内进行调节。同时,活性聚合方法和普通自由基聚合方法也对水凝胶的相转变有着重要的影响。     

Nonaqueous emulsion copolymerization of ethyl methacrylate/lauryl methacrylate in propylene glycol. I. Evaluation of stabilizing efficiency for PEO‐PS‐PEO triblock copolymers

Sixteen poly(ethylene oxide)–polystyrene–poly(ethylene oxide) (PEO‐PS‐PEO) triblock copolymers were synthesized by anionic polymerization. They were characterized by gel permeation chromatography and proton NMR. The molecular weight of these 16 PEO‐PS‐PEO triblock copolymers ranged from 5100 to 13,300. The polystyrene (PS) block length was between 13 and 41. The PEO block length was between 41 and 106. The polydispersity index for these PEO‐PS‐PEO triblock copolymers were 1.05 ± 0.02. When using these stabilizers in the emulsion copolymerization of ethyl methacrylate and lauryl methacylate in propylene glycol, only a narrow window of stability was observed. Stable latexes were formed only when the molecular weights of the PEO blocks were within the range of 5300–7700 and the molecular weights of the PS blocks were 2000–4000. The stabilizer ability for these triblock copolymers was correlated with their molecular weight and conformation in propylene glycol. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1951–1962, 2001     

Preparation,morphology and sonication time dependence of silver nanoparticles in amphiphilic block copolymers of PEO with polystyrene or PMMA

Composite materials comprising arrays of silver nanoparticles in amphiphilic copolymers have been prepared by sonochemically enhanced borohydride reduction of precursor silver nitrate (AgNO₃). The precursor was incorporated into the cores of polymeric micelles formed from block copolymers of polystyrene (PS) or poly(methyl methacrylate) (PMMA) with poly(ethylene oxide) (PEO). The copolymers were synthesised with varying hydrophobic block lengths from a PEO macroinitiator by atom transfer radical polymerization (ATRP). UV/visible spectroscopy was used to confirm the formation of elemental silver and the effect of sonication time on the appearance of the silver nanoparticles was determined. The growth was faster than when gold nanoparticles are formed in comparable block copolymers. Nanoparticles formed in copolymers with PMMA blocks were more stable to agglomeration than when polystyrene was used. Electron microscopy revealed the morphology of the nanocomposites which confirmed that both block copolymers are vehicles for the formation of well-defined films containing nanoparticulate silver. However, AgNP formation shows some significant differences from previous reports of gold NP containing materials formed under similar conditions.     

Biodegradable block copolymers with poly(ethylene oxide) and poly(glycolic acid‐valine) blocks

Biodegradable ABA triblock copolymers with poly(ethylene oxide) and poly(glycolic acid‐valine) blocks were synthesized via ring‐opening polymerization of cyclo(glycolic acid‐valine) using Ca‐alcoholates of hydroxytelechelic PEO as the initiator. The L‐valine residue racemized during copolymerization of cyclo(glycolic acid‐valine). The crystallization of the block copolymers decreases with decreasing PEO content in the triblock copolymers and with increasing length of the poly(glycolic acid‐valine) block. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2916–2919, 2002     

Synthesis and characterization of amphiphilic block copolymers of methyl methacrylate with poly(ethylene oxide) macroinitiators formed by atom transfer radical polymerization

Amphiphilic ABA triblock copolymers of poly(ethylene oxide) (PEO) with methyl methacrylate (MMA) were prepared by atom transfer radical polymerization in bulk and in various solvents with a difunctional PEO macroinitiator and a Cu(I)X/N,N,N′,N″,N″‐pentamethyldiethylenetriamine catalyst system at 85°C where X=Cl or Br. The polymerization proceeded via controlled/living process, and the molecular weights of the obtained block copolymers increased linearly with monomer conversion. In the process, the polydispersity decreased and finally reached a value of less than 1.3. The polymerization followed first‐order kinetics with respect to monomer concentration, and increases in the ethylene oxide repeating units or chain length in the macroinitiator decreased the rate of polymerization. The rate of polymerization of MMA with the PEO chloro macroinitiator and CuCl proceeded at approximately half the rate of bromo analogs. A faster rate of polymerization and controlled molecular weights with lower polydispersities were observed in bulk polymerization compared with polar and nonpolar solvent systems. In the bulk polymerization, the number‐average molecular weight by gel permeation chromatography (M_n,GPC) values were very close to the theoretical line, whereas lower than the theoretical line were observed in solution polymerizations. The macroinitiator and their block copolymers were characterized by Fourier transform infrared spectroscopy, ¹H‐NMR, matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry, thermogravimetry (TG)/differential thermal analysis (DTA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). TG/DTA studies of the homo and block copolymers showed two‐step and multistep decomposition patterns. The DSC thermograms exhibited two glass‐transition temperatures at ?17.7 and 92°C for the PEO and poly(methyl methacrylate) (PMMA) blocks, respectively, which indicated that microphase separation between the PEO and PMMA domains. SEM studies indicated a fine dispersion of PEO in the PMMA matrix. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 989–1000, 2005     

Associative properties of perfluorooctyl end‐functionalized polystyrene–poly(ethylene oxide) diblock copolymers

The synthesis of 2,2,3,3‐tetrahydro‐perfluoroundecanoyl end‐functionalized polystyrene–poly(ethylene oxide) block (PS‐block‐PEO‐R_F) copolymers and their matching PS‐block‐PEO diblock copolymers was carried out by sequential anionic polymerization. Viscometry and ¹⁹F NMR studies show that the PS‐block‐PEO copolymers, in contrast to their matching PS‐block‐PEO‐R_F copolymers, exhibit a micellar rather than the associative behavior seen for the latter. However, the presence of an excess of fluorinated acid, used for end‐functionalization, produces a reduction of the associative behavior above the overlap concentration, with the fluorinated acid acting like a surfactant. A competition may also occur between PS—and R_F—mediated micellization. Copyright © 2004 Society of Chemical Industry     

Composition and properties of complexes between anionic liposomes and diblock copolymers with cationic and poly(ethylene oxide) blocks

A series of cationic diblock copolymers were synthesized via sequential anionic polymerization of 2‐vinylpyridine and ethylene oxide and further quaternization of the resulting diblock copolymers with dimethyl sulfate. Diblock copolymers with a degree of polymerization (DP) of the cationic block equal to 40 and DP of the poly(ethylene oxide) (PEO) block equal to 45, 210 and 450, as well as a cationic homopolymer with DP = 40 (control), were adsorbed on the surface of anionic liposomes of 40–60 nm in diameter. The liposomes were constructed with egg lecithin admixed with 0.1 mole fraction of a doubly anionic lipid, cardiolipin. The liposome–polymer complexes were characterized using electrophoretic mobility measurements, dynamic light scattering, conductivity, fluorescence and UV spectroscopy, and differential scanning calorimetry. Adsorption of the polymers causes the liposomes to aggregate; the only exception is the diblock copolymer with DP of the PEO block of 450, which shows an aggregation‐preventing effect. In all cases, the integrity of liposomes is retained upon their complexation with polymers. The diblock copolymer with a short PEO block induces clustering of anionic lipid in the outer leaflet of the membrane; this effect becomes less pronounced with increasing DP of the PEO block. The differences in behaviour of the diblock copolymers are explained in terms of copolymer cluster formation via hydrogen bonding between neighbouring PEO blocks. These observations are important for interpretation of biological effects produced by cationic polymers and selection of cationic polymers for biomedical applications. © 2017 Society of Chemical Industry     

Preparation and characterization of amphiphilic block copolymer of polyacrylonitrile‐block‐poly(ethylene oxide)

The synthesis of polyacrylonitrile‐block‐poly(ethylene oxide) (PAN‐b‐PEO) diblock copolymers is conducted by sequential initiation and Ce(IV) redox polymerization using amino‐alcohol as the parent compound. In the first step, amino‐alcohol potassium with a protected amine group initiates the polymerization of ethylene oxide (EO) to yield poly(ethylene oxide) (PEO) with an amine end group (PEO‐NH₂), which is used to synthesize a PAN‐b‐PEO diblock copolymer with Ce(IV) that takes place in the redox initiation system. A PAN‐poly(ethylene glycol)‐PAN (PAN‐PEG‐PAN) triblock copolymer is prepared by the same redox system consisting of ceric ions and PEG in an aqueous medium. The structure of the copolymer is characterized in detail by GPC, IR, ¹H‐NMR, DSC, and X‐ray diffraction. The propagation of the PAN chain is dependent on the molecular weight and concentration of the PEO prepolymer. The crystallization of the PAN and PEO block is discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1753–1759, 2003     

Synthesis and characterization of oxymethylene-linked 2-vinylpyridine/oxyethylene multiblock copolymers

Oxymethylene-linked (2-vinylpyridine-oxyethylene) multiblock copolymers were prepared by coupling telechelic α,ω-dihydroxypoly(2-vinylpyridine) (THPVP) and poly(ethylene oxide) (PEO), using dichloromethane as coupling agent and KOH as catalyst. THPVP was synthesized by polymerization of 2-vinylpyridine in tetrahydrofuran/benzene using 1-methylnaphthyllithium as anionic initiator, followed by capping with ethylene oxide and termination by methanol. The effects of charging weight ratio of PEO/THPVP, copolymerization time and molecular weight of PEO or THPVP on the copolymerization were studied. The copolymers were characterized by IR, ¹H NMR, membrane osmometry, transmission electron microscopy (TEM) and differential scanning calorimetry (DSC).     

Synthesis of poly(fluorinated styrene)‐block‐poly(ethylene oxide) amphiphilic copolymers via atom transfer radical polymerization: potential application as paper coating materials

BACKGROUND: The surface of a substrate which comprises a fibrous material is brought into contact with a type of amphiphilic block copolymer which comprises hydrophilic/hydrophobic polymeric blocks. These amphiphilic copolymers have been synthesized by atom transfer radical polymerization (ATRP) technique. The atom transfer radical polymerization of poly(2,3,4,5,6‐pentafluorostyrene)‐block‐poly(ethylene oxide) (PFS‐b‐PEO) copolymers (di‐ and triblock structures) with various ranges of PEO molecular weights was initiated by a PEO chloro‐telechelic macroinitiator. The polymerization, carried out in bulk and catalysed by copper(I) chloride in the presence of 2,2′‐bipyridine ligand, led to A–B–A amphiphilic triblock and A–B amphiphilic diblock structures. RESULTS: With most of the macroinitiators, the living nature of the polymerizations led to block copolymers with narrow molecular weight distributions (1.09 < M_w/M_n < 1.33) and well‐controlled molecular structures. These block copolymers turned out to be water‐soluble through adjustment of the PEO block content (>90 wt%). Of all the block copolymers synthesized, PFS‐b‐PEO(10k)‐b‐PFS containing 10 wt% PFS was found to retard water absorption considerably. CONCLUSION: The printability of paper treated with the copolymers was evaluated with contact angle measurements and felt pen tests. The adsorption of such copolymers at the solid/liquid interface is relevant to the wetting and spreading of liquids on hydrophobic/hydrophilic surfaces. Copyright © 2009 Society of Chemical Industry