异端基遥爪聚乙二醇的合成研究进展

异端基遥爪聚乙二醇的传统合成方法是端基改性法,它是以同端基遥爪聚乙二醇为原料,对其端基进行改性,得到异端基遥爪聚乙二醇;而直接合成法是用含有不同双官能团的引发剂来引发环氧乙烷的阴离子开环聚合,获得异端基遥爪聚乙二醇,同时两活性端基还可以进一步改性,衍生出更多种类的异端基遥爪聚乙二醇。对异端基遥爪聚乙二醇的直接合成法、端基改性法和通用性合成方法的研究进展进行了综述。     

羟基偶氮酯引发剂合成双端羟基聚苯乙烯

以偶氮二异丁腈 ,乙二醇为原料合成双 ( 2 -羟乙基 ) 2 ,2′ -偶氮二异丁酸酯。将其作为引发剂 ,合成了遥爪型羟端基聚苯乙烯 ,其分子量为 3 .0× 10 3～ 6 .5× 10 3。讨论了单体浓度、引发剂浓度、聚合反应温度及反应时间对聚合转化率和产物分子量的影响。结果表明 ,聚合转化率和产物分子量随着单体浓度的增加而增加 ;而引发剂浓度增加 ,则聚合转化率明显提高 ,分子量却随之下降 ;温度升高 ,聚合转化率增加 ,产物分子量下降 ;而反应时间主要影响聚合转化率 ,对分子量影响不大。     

树枝状聚酯—聚L-赖氨酸（Z）两嵌段共聚物的合成

由2,2-二羟甲基丙酸与2,2-二甲氧基丙烷经过逐级醇酸缩合、催化加氢和端氨基化后得到端基为氨基的树枝状聚酯分子G3-C3H9N2,以此为引发剂引发ω苄氧羰基L-赖氨酸-N-羧酸酐（ω-Z—L—lysine—NCA）开环聚合得到树枝状聚酯-聚L-赖氨酸（Z）两嵌段共聚物。采用^1H—NMR、IR、GPC方法对产物进行表征。结果表明：G3-C3H9N2能有效引发NCA开环聚合,共聚物的分子量可以通过调节单体引发剂比例来控制,所得产物具有较窄的分子量分布系数。     

一种新型2，6-二亚胺吡啶席夫碱的合成与表征

本文从3，4，5-三羟基苯甲酸甲酯出发，经过经过Williamson醚反应、氯化、霍夫曼重排得到3，4，5-三苄氧基苯胺，最后用合成得到的3，4，5-三苄氧基苯胺与2，6-二乙酰基吡啶反应的得到目标产物2，6-二【1-（3，4，5-三苄氧基苯亚胺）乙基】吡啶席夫碱，并进行了NMR，元素分析，质谱等表征。     

遥爪聚异丁烯的合成

<正>1引言遥爪聚异丁烯的制备生要有2种方法,即聚合物降解法和链引发转移剂法（Inifer）。通过Inifer技术,可以得到末端带有叔氯的遥爪聚异丁烯’“,再由氯端基经有机反应转化为带有不同官能团的遥爪聚异丁烯,如C一C—[2]、羟基[3,4]、浚基”‘和苯基”’等。 Kennedy等“”‘研究表明,采用双端或三端引发剂,可得官能度凡。 2或 3土 0．二的遥爪聚异丁烯。武冠英等”‘研究探讨了合成端氯基遥爪聚异丁烯过程中的环化反应和链转移反应。本文选用双端直链烷烃叔酯为引发剂,三氯化硼为共引发剂,于CHzCI。中合成线性叔氯遥爪聚异丁烯。     

1-脱氧野尻霉素的N-取代苯丙烷衍生物的合成

以(2R,3R,4R,5S)-3,4,5-三(苄氧基)-2-((苄氧基)甲基)哌啶盐酸盐为起始原料,与取代苯乙酮及多聚甲醛在无水乙醇中经曼尼希反应缩合得到中间体1-(4-取代苯基)-3-((2R,3R,4R,5S)-3,4,5-三(苄氧基)-2-((苄氧基)甲基)哌啶-1-基)丙烷-1-酮,该中间体经Pd(OH)2/C...     

楔形树枝状二亚胺吡啶的合成及其在丙烯聚合催化剂中的应用

设计并合成了一种具有楔形树枝状结构的2,6-二［1-(4-(3,4,5-三(苄氧基)苄氧基)苯亚胺)乙基］吡啶化合物。用该化合物作为铁系丙烯聚合催化剂配体,制备出新型后过渡金属丙烯聚合催化剂,并对催化剂进行初步聚合评价。研究表明,相比传统的铁系丙烯聚合催化剂,制备的催化剂具有更高的活性,得到的聚丙烯数均分子量有较大的提高。     

一种酚羟基苄基保护基的脱除方法

提出了一种脱除酚类化合物羟基苄基保护基的方法。采用多聚磷酸(PPA)-浓盐酸-乙醇体系脱除苄基保护基,通过单因素实验考察PPA物质的量、浓盐酸与PPA体积比、反应时间以及反应温度对产率的影响。结果表明,n(PPA)=0.2 mmol、V(浓盐酸)∶V(PPA)=100∶1、反应时间3 h、反应温度85℃为最佳反应条件。采用优化条件得到9个脱苄基化合物,产率为70.4%~92.7%,其中2'-苄氧基取代查尔酮脱掉苄基的同时环合得到二氢黄酮。所得产物结构经MS、1HNMR及13CNMR进行确证。     

丙烯酰胺在聚乙二醇水溶液中可逆加成-断裂链转移聚合

结合双水相聚合和可逆加成-断裂链转移(RAFT)聚合,提出在聚乙二醇(PEG)水溶液中进行丙烯酰胺(AM)的RAFT双水相聚合,考察反应条件对聚合反应速率和产物分子量及分布的影响。结果表明:高引发剂浓度、单体浓度和聚合温度可以提高初始聚合速率和最终转化率,PEG和RAFT试剂浓度的增加会导致聚合速率减慢和最终转化率降低;峰值聚合速率随引发剂浓度、单体浓度和聚合温度的增加而增大,同时峰值聚合速率对应的时间提前;RAFT试剂浓度增加会推迟峰值聚合速率对应的时间,但可制得分子量分布较窄的产物;PEG浓度的增加会导致产物的分子量分布变宽。     

2-（2-氯乙氧基）乙醇的制备方法

二-（2-羟乙基）醚（俗称二甘醇）在甲苯中与偏硼酸酐反应得到偏硼酸三-（2-羟乙氧基-1-基）乙酯,再经氯化亚砜处理得到偏硼酸三-（2-氯乙氧基-1-基）乙酯,最后水解得到目标产物2-（2-氯乙氧基）乙醇。该工艺原料易得、操作简便、条件温和。最后总收率（以二甘醇计）达到68．3％。     

聚醚二醇钾盐引发D．L－丙交酯的开环聚合研究

以聚乙二醇－４０００钾盐为引发剂．合成了食不同长度聚醚链段的聚Ｄ．Ｌ－乳酸－聚乙二醇－聚Ｄ．Ｌ－乳酸（ＰＬＡ－ＰＥＧ－ＰＬＡ）三嵌段共聚物。考察了溶剂用量、引发剂用量、反应温度和时间、ＰＥＧ分子量、不同溶剂对聚合反应的影响。以１Ｈ－ＮＭＲ、ＩＲ、ＤＳＣ、ＧＰＣ对共聚物进行了表征。     

Synthesis of block copolymers via redox polymerization

Polymerization and copolymerization of vinyl monomers such as acrylamide, acrylonitrile, vinyl acetate, and acrylic acid with a redox system of Ce(IV) and organic reducing agents containing hydroxy groups were studied. The reducing compounds were poly(ethylene glycol)s, halogen‐containing polyols, and depolymerization products of poly(ethylene terephthalate). Copolymers of poly(ethylene glycol)s‐b‐polyacrylonitrile, poly(ethylene glycol)s‐b‐poly(acrylonitrile‐co‐vinyl acetate), poly(ethylene glycol)s‐b‐polyacrylamide, poly(ethylene glycol)s‐b‐poly(acrylamide‐co‐vinyl acetate), poly(1‐chloromethyl ethylene glycol)‐bpoly(acrylonitrile‐co‐vinyl acetate), and bis[poly(ethylene glycol terephthalate)]‐b‐poly(acrylonitrile‐co‐vinyl acetate) were produced. The yield of acrylamide polymerization and the molecular weight of the copolymer increased considerably if about 4% vinyl acetate was added into the acrylamide monomer. However, the molecular weight of the copolymer was decreased when 4% vinyl acetate was added into the acrylonitrile monomer. Physical properties such as solubility, water absorption, resistance to UV light, and viscosities of the copolymers were studied and their possible uses are discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1385–1395, 1999     

Time-resolved gel permeation chromatographic study on poly(N-isopropylacrylamide)-block-poly(ethylene glycol) prepared by soap-free emulsion polymerization

To synthesize an amphiphilic block copolymer of poly(N-isopropylacrylamide)-block-poly(ethylene glycol) (NE), an aqueous soap-free emulsion polymerization system was employed where poly(N-isopropylacrylamide) (PNIPA), polymerized from the radically activated chain ends of poly(ethylene glycol) (PEG), forms micelle cores stabilized by PEG brush chains emanating there from. When this polymerization was carried out at temperatures equal to or higher than 34 °C, narrowly-dispersed NE, which cannot be obtained by solution polymerization, was successfully obtained. To elucidate the living nature of the soap-free emulsion polymerization, time-dependent monomer conversion and molecular weight of NE was investigated by time-resolved gel permeation chromatography (GPC). The results indicate that the compartmentalization of end radicals into micelles cores leads to the quasi-living behavior of the polymerization.     

Synthesis of end-branched poly(ethylene glycol)s by aqueous atom transfer radical polymerization

Summary This article reports the synthesis of novel hydrophilic end-branched poly(ethylene glycol)s, in aqueous media by atom transfer radical polymerization (ATRP). Poly(ethylene glycol)s with molecular weights 10,000 and 16,000 were end-functionalized and used as bifunctional initiators for the polymerization of a poly(ethylene glycol) macromonomer with a molecular weight of 2,000 (PEGMA), either by aqueous ATRP or in a watedmethanol (l/l V/V) mixture. For both macroinitiators a DP of 10 was the target, giving an average of 5 branches in each end. The rates of polymerization were of the same order of magnitude when the polymerizations were initiated by either of the two macroinitiators in watedmethanol (l/l V/V). When a bifunctional oligo(ethy1ene glycol) initiator (M_n = 600) was used to study the polymerization of PEGMA in water/methanol a reduction in the rate of polymerization was observed indicating an influence of the molecular weight of the initiator on the rate of polymerization. Received 25 Maich 2002/Revised 8 November 2002/Accepted 8 November 2002 Correspondence to Jorgen Kops     

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 radical polymerization of end-allenoxy polyoxyethylene macromonomer

Poly(ethylene glycol) allenyl methyl ether (2) was prepared by the reaction of poly(ethylene glycol) monomethyl ether (the number average molecular weight (M_{n) = 550}) with propargyl bromide, followed by the base-catalyzed isomerization reaction. Functionality of end-allenyl groups in the obtained macromonomer was determined as 92% (from ¹H-NMR). The radical polymerization of 2 was carried out in bulk and in benzene at 60 or 120°C to yield a polymer with poly(ethylene glycol) side chains. For instance, a polymer (3, M_n = 3900) was obtained in 39% yield by the polymerization of 2 in bulk at 60°C for 48 h using 6 mol% of α,α′-azobisisobutyronitrile (AIBN). The obtained polymer was soluble in organic solvents as well as water.     

Relaxational behavior and swelling‐pH master curves of poly[(diethylaminoethyl methacrylate)‐graft‐(ethylene glycol)] hydrogels

Poly[(diethylaminoethyl methacrylate)‐graft‐(ethylene glycol)] hydrogels were prepared with a molar ratio of 10:1 of diethylaminoethyl methacrylate to poly(ethylene glycol) of number‐average molecular weights (M_n) 200, 400 and 1000 g mol^?1 using tetra(ethylene glycol) dimethacrylate to give a crosslinking ratio between 0.5 and 4.0 %. Glucose oxidase and catalase were immobilized in the matrix during polymerization. The maximum enzyme loading used was 6.6 × 10^?4 g of glucose oxidase per g of polymer. The equilibrium and dynamic swelling properties of these hydrogels were investigated. The pH‐dependent equilibrium swelling characteristics showed a sharp transition between the swollen and the collapsed state at pH 7.0. The dynamic response of the hydrogel discs to pH was analyzed in pulsatile pH conditions. The effects of particle size, crosslinking and molecular weight of poly(ethylene glycol) (PEG) on the dynamic swelling response were investigated. The pulsatile nature of the response was analyzed using Boltzmann superposition. Swelling–pH master curves were obtained. Copyright © 2004 Society of Chemical Industry     

The effects of solvent and initiator on anionic ring opening polymerization of ϵ‐caprolactone: synthesis and characterization

Anionic ring opening polymerization of ?‐caprolactone was studied by using different amounts of two potassium activated initiators containing ethylene glycol (EG) and polyhedral oligomeric silsesquioxane (POSS) diol, in tetrahydrofuran and toluene as solvents. The synthesized hydroxyl terminated macromers and linear poly(?‐caprolactone) (PCL) were characterized by proton and carbon nuclear magnetic resonance and gel permeation chromatography (GPC) techniques. Results showed an increase in molecular weight as the monomer/initiator molar ratio increased from 100 to 151 and 202, while the molecular weight distribution (MWD) showed a minimum by monomer concentration increase. Moreover, POSS‐diol‐initiated PCLs showed a higher MWD than the polymers initiated with the EG initiator. This was attributed to the formation of a vesicular structure of POSS diols which was confirmed by optical microscopy. By deconvolution of GPC peaks, the best conditions to synthesize PCL with the narrowest MWD were selected. Finally, the effects of some other parameters were studied in more detail.     

Effect of poly(ethylene glycol) on the solid‐state polymerization of poly(ethylene terephthalate)

Poly(ethylene glycol) (PEG) and end‐capped poly(ethylene glycol) (poly(ethylene glycol) dimethyl ether (PEGDME)) of number average molecular weight 1000 g mol^?1 was melt blended with poly(ethylene terephthalate) (PET) oligomer. NMR, DSC and WAXS techniques characterized the structure and morphology of the blends. Both these samples show reduction in T_g and similar crystallization behavior. Solid‐state polymerization (SSP) was performed on these blend samples using Sb₂O₃ as catalyst under reduced pressure at temperatures below the melting point of the samples. Inherent viscosity data indicate that for the blend sample with PEG there is enhancement of SSP rate, while for the sample with PEGDME the SSP rate is suppressed. NMR data showed that PEG is incorporated into the PET chain, while PEGDME does not react with PET. Copyright © 2005 Society of Chemical Industry