侧链末端含荧光基团芘的EC-g-PCL梳形共聚物的合成与性能研究

首先以乙基纤维素(EC)为大分子引发剂引发ε-己内酯(CL)的开环聚合反应(ROP),合成乙基纤维素接枝聚ε-己内酯的梳形共聚物(EC-g-PCL).之后利用N,N'-二环己基碳二亚胺(DCC)做脱水剂将荧光基团芘(Pyr)引入侧链聚ε-己内酯(PcL)末端,经控制投料比,合成不同含量芘端基的乙基纤维素接枝聚ε-己内酯...     

己内酯和丙交酯的微波辅助开环聚合反应

己内酯和丙交酯在异辛酸亚锡存在下经微波辐照 5min可分别获得分子量 1 2 0kg·mol- 1的聚己内酯和 2 2 5kg·mol- 1 的聚乳酸。苯甲酸可作为己内酯微波辅助开环聚合的引发剂 ,所得聚己内酯的分子量达到 44 8kg·mol- 1 。通过混有布洛芬的己内酯的微波开环聚合可直接制备以聚己内酯为基质的药物控释系统。己内酯和丙交酯在微波辐照下的热行为对它们的开环聚合反应有重要影响。     

有机小分子催化ε-己内酯开环聚合反应

聚己内酯(PCL)是一种生物可降解高分子材料,具有良好的环境、生物相容性,广泛应用于生物医学、包装等领域。有机小分子催化ε-己内酯单体开环聚合反应是制备聚己内酯的主要方式之一。与传统的金属催化相比,有机催化不仅反应条件温和、聚合可控,而且还可解决聚合物中金属残留问题,是目前高分子合成化学的研究热点。本文按照催化体系的不同活化方式,讨论了近年来有机催化在ε-己内酯开环聚合反应中的研究进展,归纳总结了不同催化体系的优缺点,并在此基础上展望了有机小分子催化剂在ε-己内酯开环聚合反应中的发展趋势和应用前景。     

稀土席夫碱配合物催化己内酯可控开环聚合

 通过稀土氯化物与席夫碱钠盐的交换反应制备了一系列以 3,5-二叔丁基水杨醛缩苯胺为配体的稀土席夫碱配合物. 对其中的钕席夫碱配合物进行了 X射线单晶衍射分析, 发现其单晶结构为五角双锥构型, 所得席夫碱稀土配合物可以单组分催化 ?-己内酯开环聚合. 深入研究了钕席夫碱配合物催化己内酯的开环聚合机理, 考察了不同聚合条件对单体转化率、产物分子量及分子量分布的影响. 结果表明, 该聚合反应速率为一级, 聚合反应具有较好的可控性. 聚合物端基分析表明, 聚合反应以配位-插入机理进行.     

有机小分子催化ε-己内酯开环聚合反应

聚己内酯(PCL)是一种生物可降解高分子材料,具有良好的环境、生物相容性,广泛应用于生物医学、包装等领域。有机小分子催化ε-己内酯单体开环聚合反应是制备聚己内酯的主要方式之一。与传统的金属催化相比,有机催化不仅反应条件温和、聚合可控,而且还可解决聚合物中金属残留问题,是目前高分子合成化学的研究热点。本文按照催化体系的不同活化方式,讨论了近年来有机催化在ε-己内酯开环聚合反应中的研究进展,归纳总结了不同催化体系的优缺点,并在此基础上展望了有机小分子催化剂在ε-己内酯开环聚合反应中的发展趋势和应用前景。     

羟基酸引发ε-己内酯开环聚合的研究

研究了水、醇、羧酸存在下ε 己内酯开环聚合的情况 ,发现在适当温度下 (80℃ ) ,羧基并不引发ε 己内酯的开环聚合 ,但对羟基引发ε 己内酯开环聚合起加速作用 ,而且催化能力与酸度有关 .进而又对羟基酸(乙醇酸、DL 苹果酸、柠檬酸 )引发ε 己内酯开环聚合做了研究 ,合成了一系列含不同数目遥爪羧基的α 羟基 ω 羧基 (1,2 ,3)己内酯低聚物 (HCPCL) ,并对其结构做了酸值滴定、羟值滴定、UV、FTIR与1H NMR分析 .对羧基催化羟基引发ε 己内酯开环聚合的机理做了分析     

基于NNTA可控聚合的环形聚类肽合成与表征

研究了1,8-二氮杂二环十一碳-7-烯(DBU)引发的N-取代甘氨酸-N-硫代羧酸酐(NNTA)开环聚合.聚合通过两性离子开环聚合机理进行,表现出良好的可控性,聚合产率高(86%),分子量可控(900～7500 g/mol),分子量分布较窄(1.13～1.25).通过~1H-NMR、~(13)C-NMR谱图、MALDI-ToF质谱和红外光谱等表征手段,证明所得聚合产物具有环形结构,且聚合物链上带有DBU残基和硫代氨基甲酸酯基团.与苄胺(BA)引发所得的线形聚类肽相比,DBU引发所得的聚类肽具有更小的流体力学体积,进一步证明了其环形结构.扩链反应表明,加入新单体后聚合反应仍可以继续进行,产物分子量显著增加,表明了DBU引发的NNTA聚合具有活性特征. DBU引发的NNTA两性离子开环聚合是一种简便、高效的环形聚类肽合成方法.     

茂基二价钐配合物高效催化己内酯开环聚合

研究了二茂基二价钐配合物(C5H5)2Sm(THF)作为单组分催化剂催化己内脂开环聚合反应,考察了催化剂用量、聚合反应时间、聚合反应温度对己内酯聚合反应的影响。结果表明,配合物(C5H5)2Sm(THF)对己内酯聚合有极高的催化活性且产物的数均分子量较高,当催化剂与单体摩尔比为1：5000时,聚合产率仍可达50.3%,数均分子量可高达32.4万;温度升高,聚合反应的转化率增加,聚合产物数均分子量降低;催化剂用量增加,聚合转化率增加,聚合产物分子量降低;聚合产物的分子量分布较窄;通过凝胶色谱法对聚合产物的分子量及分子量分布进行了表征。     

原位生成三苄氧基钇催化ε-己内酯可控开环聚合

以烷基钇[Y( CH2 SiMe3),(THF)2]与苯甲醇原位反应生成的三苄氧基钇为引发剂,研究ε-己内酯(CL)可控开环聚合反应(ROP).结果表明,随着聚合体系中单体/引发剂摩尔比的增大,产物聚己内酯(PCL)的数均分子量(1H NMR计算和GPC测定)均随之线性增加,且分子量分布(Mw/Mn=1.4～1.1)逐...     

两亲性嵌段共聚物PCL-b-PNVP的合成及其自组装行为的研究

以4-羟基-2,2,4,4-四甲基哌啶氮氧自由基为引发剂,通过ε-己内酯（ε-CL）的开环聚合反应,合成氮氧稳定自由基为末端基的聚己内酯（PCL-T）;在其＂介调＂下,进行乙烯基吡咯烷酮（NVP）的氮氧稳定自由基聚合（NMP）,得到结构规整聚己内酯和聚乙烯吡咯烷酮两亲性的嵌段共聚物（PCL-b-PNVP）.通过核磁共振...     

Ring opening polymerization of adipic anhydride initiated by dibutylmagnesium initiator

The ring opening polymerization of adipic anhydride (AA) initiated by dibutylmagnesium has been investigated in solution and in bulk. The results indicate that dibutylmagnesium is quite effective for the ring opening polymerization of AA. The polymer has been characterized by ¹H-NMR, IR and DSC. The end group analysis suggests that the AA polymerization might proceed through the “coordination-insertion” mechanism based on the acyl-oxygen cleavage of the AA ring.     

Homopolymerization and Copolymerization of Adipic Anhydride with ε-Caprolactone Catalyzed by Rare Earth Trisphenolate

The ring-opening polymerization of adipic anhydride and the ring-opening copolymerization of adipic anhydride with ε-caprolactone catalyzed by single component rare earth trisphenolate have been reported. The structure of the copolymer poly（CL-b-AA） has been characterized by SEC, ^1H NMR and DSC.     

Synthesis and characterization of biodegradable poly(ester anhydride) based on ε‐caprolactone and adipic anhydride initiated by potassium poly(ethylene glycol)ate

Novel biodegradable poly(ester anhydride) block copolymers based on ε‐caprolactone (ε‐CL) and adipic anhydride (AA) were prepared by sequential polymerization. ε‐CL was first initiated by potassium poly(ethylene glycol)ate and polymerized into active chains (PCL‐O^?K⁺), which were then used to initiate the ring‐opening polymerization of AA. The effects of the AA feed ratio, solvent polarity, monomer concentration, and temperature on sequential polymerization were investigated. The copolymers, obtained under different conditions, were characterized by Fourier transform infrared, ¹H NMR, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). The GPC results showed that the weight‐average molecular weights of the block copolymers were approximately 6.0 × 10⁴. The DSC results indicated the immiscibility of the two components. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1511–1520, 2003     

Melt Polymerization of Adipic Anhydride (Oxepane-2,7-Dione)

Oxepane-2,7-dione (1) was prepared by the reaction of adipic acid and acetic anhydride followed by catalytic depolymerization under vacuum. the ring-opening polymerization of (1) was investigated in the melt, and was studied as a function of polymerization temperature, time and concentration of catalyst (stannous 2-ethylhexanoate). from ¹H-NMR and IR spectra it can be deduced that stannous 2-ethylhexanoate coordinates with the anhydride bond of the ring, and that the resulting species reacts with the monomer by ring-opening of the acyl-oxygen bond. These observations indicate a non-ionic insertion polymerization mechanism at the beginning of the reaction, but after 2 h at 80°C, anhydride exchange appears to be the dominating reaction. Ring-opening melt polymerization of (1) resulted in low molecular weight poly (adipic anhydride).     

A novel catalyst of lanthanum tris(2,6-di-tert-butyl-4-methylphenolate) for ring-opening polymerization of adipic anhydride

Lanthanum tris(2,6-di-tert-butyl-4-methylphenolate) exhibits high catalytic activity toward the ring-opening polymerization of adipic anhydride. Poly(adipic anhydride) (PAA, M_n=1500) was obtained with a conversion of 86.0% within 1 h in methylene chloride at 20 °C. Three melting peaks were found in the DSC curve of the polymer at 51.4, 64.5 and 108.9 °C, respectively.     

Equilibrated radical polymerization of acrylic propionic anhydride as a mono-ene counterpart of acrylic anhydride

Radical polymerization of acrylic propionic anhydride (APA) as a mono-ene counterpart of acrylic anhydride (AA) was investigated in order to obtain supporting evidence for a previously proposed mechanism based on polymerization equilibrium for the cyclopolymerization of AA. The deviation from first-order dependence of the rate of polymerization R_p on monomer concentration was enhanced by a decrease in monomer concentration. The Arrhenius plot of lnR_p vs. 1/T was clearly curved in a highly dilute system. These results suggest increased significance of the depropagation reaction equilibrated with propagation under polymerization conditions favorable to five-membered ring formation in cyclopolymerization of AA. Under these conditions, the disproportionation reaction of APA became important and the liberated AA was incorporated into the polymer chain through copolymerization with APA, resulting in poly(APA-co-AA) having five-membered anhydride units.     

Synthesis of Poly(Adipic Anhydride) by Use of Ketene

Polyadipic anhydrides were prepared (a) from the mixed anhydride of adipic acid and acetic acid, (b) from the mixed anhydride of adipic acid and ketene in tetrahydrofurane solution (0°C), (c) by melt polycondensation of adipic acid with ketene, and (d) from the seven-membered ring adipic anhydride. The polymers were characterized by means of NMR, IR, DSC, and GPC. The polymer with the highest melting temperature was obtained by melt polycondensation of adipic acid with ketene (T _peak 76°C). The heat of fusion was approximately 40 J/g in all four methods. The number-average and weight-average molecular weights of the polyanhydrides were 2000 and 3000, respectively.     

Further discussion of the cyclopolymerization of acrylic anhydride in terms of ring size control

Radical cyclopolymerization of acrylic anhydride (AA) was conducted under various polymerization conditions to yield highly cyclized polymer, and the content of the five-membered ring of cyclic poly-AA obtained was examined in detail. Five-membered ring formation was favored with increased solvent polarity, raised polymerization temperature, and decreased monomer concentration; the ring size of the cyclic structure could be controlled freely by choosing appropriate polymerization conditions. In addition to these results, the rate of polymerization and the molecular weight of the polymer were reduced under polymerization conditions where the five-membered ring formation was favored. Finally, a mechanistic discussion is given in order to interpret these results; a reaction scheme for propagation based on polymerization equilibrium is proposed.     

Chemoselective acylation of some oxidofunctionalised organolithium compounds

Once oxidofunctionalised organolithium compounds 1 (easily prepared by reductive ring opening of isochroman and phthalan by DTBB-catalysed lithiation) were transmetallated with ZnBr₂/CuCN·2LiCl and reacted successively with a carboxylic acid anhydride and an acyl chloride in THF at 0°C, the corresponding differently acylated compounds 4 were obtained after hydrolysis with water. The anhydride performed the O-acylation exclusively and the acyl chloride carried out the C-acylation.     

AB型两亲聚L-谷氨酸-苄酯-聚乙二醇嵌段共聚物的合成与表征

利用L 谷氨酸和苯甲醇反应制备了L 谷氨酸 苄酯 ,然后将其与三聚光气反应制备了N 羧基 L 谷氨酸 环内酸酐 (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 ) ,并以此作为引发剂 ,引发NCA开环聚合 ,合成了不同分子量的聚L 谷氨酸 苄酯 聚乙二醇单甲醚 (PBGM )嵌段共聚物 .利用IR、1 H NMR、DSC、GPC等方法对共聚物结构进行了表征 .结果表明 ,MPEG NH2 引发NCA开环聚合得到的是嵌段共聚物 ,通过1 H NMR谱得到共聚物组成及数均分子量 ;随着共聚物中MPEG含量的增高 ,聚L 谷氨酸 苄酯的亲水性有所改善