自由基引发的可注射PLA-b-PEG-b-PLA大分子单体和α-CD超分子结构水凝胶的合成与表征

以数均分子量为6000的聚乙二醇为引发剂,以辛酸亚锡为催化剂引发丙交酯开环,再用甲基丙烯酸酐进行封端生成大分子单体.然后将大分子单体和α-环糊精混合,分别用维生素C和硫酸亚铁与过硫酸铵组成的氧化还原引发剂引发聚合,得到了两种不同结构的超分子结构水凝胶.用1HNMR,FTIR,TGA和XRD等分析测试手段对大分子单体及形成的水凝胶进行了表征.流变仪测试结果表明,该水凝胶固化时间合适,并具有可注射性.     

6-O-甲基丙烯酰基-D-吡喃半乳糖的水相原子转移自由聚合

合成了一种含半乳糖基团的水溶性单体6-O-甲基丙烯酰基-D-毗喃半乳糖(GMA),详细考察了其在水相中的原子转移自由聚合(ATRP),并合成了分子量分布较窄的均聚物和共聚物.用1H-NMR和GPC对聚合物进行了表征.研究表明:当引发剂为2-溴丙酸甲酯(2-MBP),铜盐配合物为CuBr/2,2'-联吡啶时,聚合可控性较差,单体转化率较低;在聚合体系中加入适量溴化铜并同时采用甲醇和水的混合溶剂,可提高GMA的ATRP可控性;加入四甲基溴化铵,并改用N,N,N',N",N"-五甲基二亚乙基三胺(PMDETA)为配体,可有效抑制二价铜的水解,提高单体的转化率;用大分子引发剂和顺序加单体法可直接合成GMA的双亲水性两嵌段共聚物.     

可聚合的光引发转移终止剂合成接枝共聚物

采用一种可聚合的光引发转移终止剂 ,2 N ,N 二乙基二硫代氨基甲酰氧基乙酸 β 甲基丙烯酰氧基乙酯 (MAEDCA) ,通过两种途径制备了含有聚甲基丙烯酸甲酯 (PMMA)和聚苯乙烯 (PSt)链段的接枝共聚物 .其一是将MAEDCA作为引发剂 ,在紫外光照射下引发MMA聚合 ,得到大分子单体 ,通过大分子单体与St的共聚合得到 .考察了所用大分子单体的分子量和浓度对共聚合的影响 .其二是将MAEDCA作为单体与MMA共聚得到侧链上含有N ,N 二乙基二硫代氨基甲酰氧基 (DC)基团的无规共聚物 ,P(MMA co MAEDCA) .在紫外光照射下 ,P(MMA co MAEDCA)作为大分子引发剂引发St聚合 ,得到P(MMA co MAEDCA) g PSt的共聚物 ,研究了接枝共聚合过程的活性自由基聚合特征     

叶立德活性聚合制备基于聚亚甲基的大分子单体

利用叶立德活性聚合方法制备了两种基于聚亚甲基的大分子单体. 其中一种是以叶立德活性聚合制备的主链链端含有羟基的聚亚甲基(PM-OH)为原料, 通过链端羟基的基团转换, 得到链端含有甲基丙烯酸酯基的大分子单体. 另一种则是以硼烷-四氢呋喃(BH₃-THF)和二乙烯基苯反应得到的三烷基硼中间体为催化剂和引发剂, 然后进行叶立德活性聚合, 再经过二水合氧化三甲胺(TAO)的氧化, 最终得到基于聚亚甲基的一端含有羟基另一端含有苯乙烯基的大分子单体. 通过高温核磁氢谱、傅立叶红外光谱和高温凝胶色谱法表征了这两种大分子单体的链结构和分子量及其分布.     

基于光聚合星型PEG-b-PCL大分子单体可生物降解水凝胶的合成及表征

以辛酸亚锡为催化剂 ,通过星型聚乙二醇 (PEG)引发ε 己内酯 (CL)开环聚合 ,制备了PEG b PCL嵌段共聚物 ,进一步以丙烯酸酯封端 ,合成了 3种水溶性大分子单体 .以 2 ,2 二甲氧基 2 苯基苯乙酮为引发剂 ,在紫外光作用下 ,大分子单体在水中由于胶束的形成能够迅速聚合形成水凝胶 .利用1 H NMR、FTIR、DSC、TGA、ESEM、凝胶含量、溶胀比等分析测试手段对大分子单体及其形成的水凝胶进行了表征 .结果表明 ,干胶迅速吸水而达到溶胀平衡 ,水凝胶具有较大的溶胀比和高的水含量 ;随着PEG臂数的增加 ,干胶的熔融峰顶温度下降 ,凝胶的溶胀比减小 ;ESEM图片上清晰地表明水凝胶的网络结构     

三官能度甲基丙烯酰氧基单体的合成与性能研究

用甲基丙烯酰氯分别与二乙醇胺和三乙醇胺反应合成了两种三官能度甲基丙烯酰氧基单体.以实时红外光谱(RT-IR)法研究了两种单体的光聚合动力学性质,考察了不同单体、不同引发剂和引发剂浓度、不同光强对聚合性能的影响,并采用动态力学分析仪(DMA)测试了光固化后材料的力学性能.结果表明,随着引发剂浓度的增大,单体转化率、最大反应速率都增大,随着光强的增大,单体转化率、最大反应速率都降低.与二苯甲酮(BP)相比,2-羟基-2-甲基-1-苯基丙酮(1173)对两种单体具有较好的引发效果.两种单体加入三缩四乙二醇双甲基丙烯酸酯(SR209)中后,对体系光固化后的产物力学性能有不同影响.     

“活”的α-甲基苯乙烯共聚物:聚合反应新化学和材料工程新技术

高于临界聚合反应温度时,α-甲基苯乙烯(AMS)单体和其聚合物处于聚合-解聚平衡.基于AMS聚合物在受热时可裂解生成大分子链自由基的特性,提出了含AMS结构单元的共聚物是一种"活"的,可作为大分子自由基引发剂的概念,并通过实验对AMS共聚物的引发性能和应用进行了研究.首先,合成了AMS与(甲基)丙烯酸酯类单体、丙烯酸、苯乙烯和马来酸酐等的共聚物.然后以上述共聚物为大分子引发剂,在90℃引发(甲基)丙烯酸酯类单体和苯乙烯等的本体聚合、溶液聚合和乳液聚合,得到了嵌段共聚物.用ESR谱证明了AMS的共聚物在加热时能裂解生成以碳原子为中心的大分子链自由基.此外,在聚合物的熔融共混中,AMS分解产生的大分子链自由基通过偶合反应形成接枝链,原位生成相容剂.AMS共聚物还可以对碳纳米管及无机粒子进行表面原位接枝改性.AMS共聚物是一类无小分子残留的绿色自由基引发剂,可以用于低成本制备两嵌段共聚物,也可以用于聚合物的熔融共混增容.     

P（DMAA-co—AM）水凝胶制备及其固定a-淀粉酶研究

采用氧化还原引发体系,水溶液聚合法制备P（DMAA-co-AM）水凝胶,并以其作为载体固定a-淀粉酶。采用单一变量法研究交联剂（N,N＇-亚甲基双丙烯酰胺）用量、引发剂（过硫酸铵）用量、单体浓度和单体配比对凝胶性能的影响。以水凝胶的最大平衡溶胀度为指标,得出制备P（DMAA-co-AM）水凝胶的优化条件：交联剂用量为0．3％,引发剂用量为0．6％,单体浓度为20％,N,N’-二甲基丙烯酰胺与丙烯酰胺的摩尔比为2：1。在优化条件下,采用原位聚合法固定a-淀粉酶,测定不同单体配比的P（DMAA-co-AM）水凝胶固定化a-淀粉酶的活性。     

P(DMAA-co-AM)水凝胶制备及其固定α-淀粉酶研究

采用氧化还原引发体系,水溶液聚合法制备P(DMAA-co-AM)水凝胶,并以其作为载体固定α-淀粉酶。采用单一变量法研究交联剂(N,N’-亚甲基双丙烯酰胺)用量、引发剂(过硫酸铵)用量、单体浓度和单体配比对凝胶性能的影响。以水凝胶的最大平衡溶胀度为指标,得出制备P(DMAA-co-AM)水凝胶的优化条件:交联剂用量为0.3%,引发剂用量为0.6%,单体浓度为20%,N,N′-二甲基丙烯酰胺与丙烯酰胺的摩尔比为2∶1。在优化条件下,采用原位聚合法固定α-淀粉酶,测定不同单体配比的P(DMAA-co-AM)水凝胶固定化α-淀粉酶的活性。     

高性能胰蛋白酶分子表面印迹材料的制备及其大分子识别特性研究

以交联聚乙烯醇(CPVA)微球为基质,以甲基丙烯酸(MAA)为功能单体,在中性水介质中制备了高性能胰蛋白酶(TRY)大分子表面印迹材料。首先通过CPVA微球表面的羟基与甲基丙烯酰氯之间的酯化反应,将大量可聚合双键甲基丙烯酰基(MAO)引入微球表面,获得改性微球MAO-CPVA。在中性水溶液中,单体MAA的羧基几乎发生完全电离,凭借强烈的静电相互作用,MAA自动结合在碱性蛋白TRY大分子周围,形成单体-模板复合体。水溶液中过硫酸铵/亚硫酸氢钠引发体系所产生的自由剂,使包围在TRY周围的单体MAA与交联剂N,N'-亚甲基双丙烯酰胺(MBA)在微球MAO-CPVA表面发生接枝交联聚合,而模板TRY则被包裹在交联网络之中,除去模板后便得到了TRY表面印迹微球MIP-PMAA/CPVA。深入考察了该表面印迹微球的大分子识别性能。研究结果表明,表面印迹微球MIP-PMAA/CPVA对TRY具有优良的结合亲和性,结合容量高达84mg·g~(-1)(3.6μmol·g~(-1));对模板蛋白TRY具有特异的识别选择性,相对于另一种碱性蛋白木瓜蛋白酶,印迹微球对TRY的选择性系数高达21.62。     

Self‐reinforcing hydrogels comprised of hydrophobic methyl methacrylate macromers copolymerized with N,N‐dimethylacrylamide

Methyl methacrylate macromers were synthesized by a catalytic chain‐transfer polymerization, with number‐average molecular weight values ranging from 600 to 26,000. These macromers subsequently were copolymerized with dimethyl acrylamide in bulk by γ radiation to yield transparent xerogel materials. The copolymerization was confirmed by NMR analyses and by subsequent aqueous extractions of the resultant copolymers. On swelling in deionized water, hydrogels were formed that had significantly higher Young's moduli than hydrogels based on statistical methyl methacrylate/dimethyl acrylamide copolymers of equivalent composition. If macromers of high molecular weight were used, phase separation occurred, resulting in opaque hydrogel compositions. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 810–817, 2000     

Poly(ethylene imine) hybrids containing polyhedral oligomeric silsesquioxanes: Preparation, structure and properties

Both octaglycidyletherpropyl polyhedral oligomeric silsesquioxane and hepta(3,3,3-trifluoropropyl)glycidyletherpropyl polyhedral oligomeric silsesquioxane were synthesized via the hydrosilylation reactions between octahydrosilsesquioxane [and/or hepta(3,3,3-trifluoropropyl)hydrosilsesquioxane] and allyl glycidyl ether. The polyhedral oligomeric silsesquioxane (POSS) macromers were characterized by means of Fourier transform infrared and nuclear magnetic resonance spectroscopy. The inter-component macromolecular reactions between the POSS macromers and poly(ethylene imine) (PEI) were employed to prepare the POSS-containing organic-inorganic PEI hybrids. The inclusion of octaglycidyletherpropyl POSS into PEI results in the formation of the organic-inorganic hybrid networks whereas the introducing hepta(3,3,3-trifluoropropyl)glycidyletherpropyl POSS to PEI affords the linear POSS-grafted PEI copolymers. Differential scanning calorimetry and thermogravimetric analysis show that the POSS-containing PEI hybrids displayed increased glass transition temperatures (T_g’s) and enhanced thermal stability compared to the plain PEI. These PEI hybrid composites can be significantly swollen with water without dissolving, suggesting the formation of hydrogels. The PEI hydrogels containing octaglycidyletherpropyl POSS is in reality the chemically-crosslinked hydrogels whereas the those containing hepta(3,3,3-trifluoropropyl)glycidyletherpropyl POSS displayed the behavior of physical hydrogels. The formation of physical hydrogels is ascribed to the microphase-separated morphology in the hybrids. In addition, the hybrids containing hepta(3,3,3-trifluoropropyl)glycidyletherpropyl POSS exhibited the typical amphiphilicity as evidenced by the increase in surface hydrophobilicity.     

Structure and properties of urea-crosslinked star poly[(ethylene oxide)-ran-(propylene oxide)] hydrogels

Isocyanate-terminated six armed star shaped macromers with a statistical copolymer backbone consisting of 80% EO and 20% PO have previously demonstrated excellent protein and cell repellence as nano-layered surfaces. In this study, various macromers are mixed with water and provide a spectrum of materials that range from particles to uniform hydrogels. Due to hydrophobic end groups, 3 kDa molecular weight macromers result in micro and nano-particles, while 18 kDa macromers completely dissolve and consequently uniform, transparent, high water content hydrogels are formed. Oriented channels may be induced into these hydrogels through the controlled freezing of water in the preformed hydrogel.     

光聚合α-CD组装超分子结构水凝胶的合成与表征

1990年, Harada等[1,2]首先观察到α-环糊精(α-CD)与PEG形成的结晶包结物(ICs). 进一步的研究发现, n=400～10 000的PEG均能与α-CD形成结晶ICs, 其形成速率与n有关, n=1 000的PEG形成ICs的速率最快. 由于α-CD是通过与相邻α-CD的氢键作用、空间立体配位及其疏水空腔与聚合物链形成包结物, 这种包结物也称为多聚准轮烷.     

Micelle formation and reaction kinetics of a bioabsorbable polyethylene glycol-oligolactide ABA block copolymer hydrogel

Bioabsorbable hydrogels are useful in a variety of medical applications. Water soluble macromers composed of polyethylene glycol (PEG)-oligo(d,l-lactide) ABA block copolymers end-capped with acrylate groups can be photopolymerized on tissue to provide hydrogels. The synthesis, characterization and photopolymerization of these monomers using either ultra-violet or visible light have been reported previously. The size and number of micelles in solution are elements in the optimization of both the extent and rate of polymerization. In the present study, gel modulus and end group analysis methods were used to characterize the degree of conversion of gel formed from macromers having various oligo(d,l-lactide) (A) block lengths. The formation of micelles was studied using dye solubilization and surface tension measurements. The kinetics of gelation of these macromers showed correlation of polymerization rate with the length of the hydrophobic A block length. The increase in hydrophobic components may cause an increase in the micelle number concentration per unit volume, which is known to directly affect the rate of emulsion polymerization. The hydrophobic segment length is therefore a useful tool for controlling the gel formation on tissue.     

Self-Forming Norbornene-Tetrazine Hydrogels with Independently Tunable Properties

Although photopolymerization reactions are commonly used to form hydrogels, these strategies rely on light and may not be suitable for delivering therapeutics in a minimally invasive manner. Here, hyaluronic acid (HA) macromers are modified with norbornene (Nor) or tetrazine (Tet) and upon mixing click into covalently crosslinked Nor-Tet hydrogels via a Diels–Alder reaction. By incorporating a high degree of Nor and Tet substitution, Nor-Tet hydrogels with a broad range in elastic moduli (5 to 30 kPa) and fast gelation times (1 to 5 min) are achieved. By pre-coupling methacrylated HANor macromers with thiolated peptides via a Michael addition reaction, Nor-Tet hydrogels are peptide-functionalized without affecting their physical properties. Mesenchymal stem cells (MSCs) on RGD-functionalized Nor-Tet hydrogels adhere and exhibit stiffness-dependent differences in matrix mechanosensing. Fluid properties of Nor-Tet hydrogel solutions allow for injections through narrow syringe needles and can locally deliver viable cells and peptides. Substituting HA with enzymatically degradable gelatin also results in cell-responsive Nor-Tet hydrogels, and MSCs encapsulated in Nor-Tet hydrogels preferentially differentiate into adipocytes or osteoblasts, based on 3D cellular spreading regulated by stable (HA) and degradable (gelatin) macromers.     

Effect solvatant des copolymères styrène–macromère a chaîne polyoxyéthylène. Influence du support polymère

Polyoxyethylene macromers were used to prepare functionalized linear and crosslinked copolymers with styrene and divinylbenzene. Gel or macroporous resins were prepared. These copolymers and resins were used as anionic activators for the Williamson reaction of potassium phenoxide and alkyl bromides under solid–liquid or solid–liquid–liquid (triphase) conditions. In contrast to similar resins obtained from chemical grafting of polyoxyethylene onto chloromethylated styrene–divinylbenzene polymers, the activity factors were strongly dependent on the composition of the resins and their morphology: an optimum activity was obtained for a 0.05M fraction of macromers in soluble copolymers and crosslinked resins. In addition, a macroporous resin with large pores was more efficient than a gel-type resin of similar composition. These effects are discussed in terms of accessibility of the activating group and compatibility of the support with the medium.     

聚氧乙烯大分子单体合成和应用(Ⅰ)——烯丙基端基聚氧乙烯大分子单体的合成和表征

本文报道了合成烯丙基端基采氧乙烯大分子单体的两种方法(引发法和封端法)。合成产物具有预期的结构。获得的大分子单体与小分子丙烯酰胺共聚,可得到不同组成的共聚物。考察了大分子单体合成条件和端基重排因素,获得了这种大分子单体制备的适宜条件。     

Synthesis and Application of Polyethylene Oxide Macromers (Ⅰ——Synthesis and Characterization of Poly(Ethylene Oxide)Macromers with Allyl-End Group

Polyethylene oxide(PEO) macromers with allyl-end group were synthesized by two different methods(initiating and deactivating).The products obtained were characterized accurately by means,of several techniques including H NMR,IR,VPO,GPC and the double-bond titration,and the results show that such kinds of product possess expected structure.The macromers were copolymerized with small molecular acrylamide,and a series of copolymers with different composition,were obtained by adjusting copolymerization conditions.Moreover,some evidence concerning allyl-group rearrangement in synthesis of the macromers was observed and suitable condition for laboratorial preparation of the macromers is proposed.