ATRP法合成聚去氢枞酸丙烯酸乙二醇酯的研究

本研究从歧化松香中提取的去氢枞酸(DHA)出发,经酰氯化后与丙烯酸(2-羟基)乙酯反应,合成了去氢枞酸丙烯酸乙二醇酯(DHAAGE);并以此为单体,2-溴-异丁酸乙酯(EBr-iB)为引发剂,CuBr/2,2'-联吡啶(2,2'-bipyridine)为催化体系,在90 oC下,利用原子转移聚合(ATRP)法制备了聚去氢枞酸丙烯酸乙二醇酯(PDHAAGE).利用FT-IR、1H-NMR和GPC对所制备的单体和聚合物进行了表征,同时考察了单体转化率随聚合反应时间的变化.结果表明,聚合反应动力学曲线呈良好线性关系,表观聚合速率常数kp′为3.6 ×10-7 s-1;所得聚合物的分子量分布很窄.     

枞酸乙二醇单酯与双酯的合成工艺研究

采用L39^4正交实验研究了枞酸乙二醇单酯与双酯的合成工艺。探讨了反应温度、催化剂用量、反应物料摩尔比、反应时间等诸因素对转化率及选择性的影响。结果表明：反应温度与反应物料摩尔比分别对转化率及选择性具有最显著的影响。实验提供了枞酸乙二醇单酯与双酯的优化合成条件,在此基础上以松香为原料进行了验证。     

去氢枞酸蔗糖酯的溶剂法合成

松香主要成分是二萜树脂酸(C29H29COOH,含量约为90％),可用作表面活性剂的合成原料。将松香树脂酸与蔗糖进行酯化反应,即可合成松香-蔗糖基非离子表面活性剂。目前关于高级脂肪酸蔗糖酯和松香基表面活性剂的研究有许多报道,但有关松香蔗糖酯的研究报道极少,工艺极不成熟,且都使用未经改性的松香,结构中仍保留两个易氧化的双键,不利于长时间储存和使用。从歧化松香中分离提纯去氢枞酸,     

聚二甲基丙烯酸乙二醇酯壁材微胶囊的制备及其表征

采用界面自由基聚合的方法,制备了以聚二甲基丙烯酸乙二醇酯(PEGDMA)为壁材,薄荷素油(DPO)与石蜡或者三辛癸酸甘油酯(GTCC)的混合物为芯材的微胶囊.微胶囊壁材是二甲基丙烯酸乙二醇酯(EGDMA)单体通过界面自由基聚合形成的高聚物PEGDMA.提出了该界面自由基聚合形成PEGDMA的机理过程.利用光学显微镜和扫描电镜探究了乳化剂类型、芯材组成和固化温度对微胶囊形貌的影响.用傅里叶红外光谱对微胶囊的化学结构进行了表征.利用紫外分光光度计测出了未被微胶囊包埋的芯材占总芯材的百分比(free oil).并用热重分析仪分析了微胶囊的热稳定性能,讨论了固化时间对微胶囊热性能的影响.结果表明,采用阿拉伯树胶为乳化剂,芯材组成为质量比M_(DPO)/M_(GTCC)=1∶1,在60℃下固化1 h,制备出的微胶囊为饱满的球形状,表面光滑.同时测得该体系中芯材的free oil为26.5 wt%.PEGDMA微胶囊在60℃固化温度下反应3 h,具有很好热稳定性,且固化温度升高能提高微胶囊的热稳定性.所制备的微胶囊无毒,在个人护理品和医药领域具有广泛的应用前景.     

新型杀菌农药去氢枞酸铜乳油有效成分分析

本文选用高效液相色谱法测定去氢枞酸的含量，从而可以推算去氢枞酸铜的含量。此分析方法的回收率为98％～101％，变异系数为2．96％。     

去氢枞醇杂环类化合物的合成及细胞毒性研究

以去氢枞酸(1)为原料,经氢化铝锂还原得到去氢枞醇(2),2与氯乙酰氯在氮气保护和DMAP催化条件下反应合成中间产物去氢枞醇氯乙酸酯(3),3与杂环化合物经亲核取代反应合成了12个新型去氢枞醇杂环类化合物(4a ～41).利用IR、1H NMR、13C NMR和HR-MS等对目标化合物的结构进行表征,采用MTT法测试目...     

苯乙酮类去氢枞酰腙的合成

以去氢枞酸为原料,经三氯化磷酰氯化得到去氢枞酰氯(2);2与85%水合肼反应合成了去氢枞酰肼(3);3再分别与苯乙酮及其衍生物发生缩合反应得到4个新型的苯乙酮类去氢枞酰腙化合物,其结构经UV,1H NMR和IR表征.     

聚对苯二甲酸乙二醇酯/碳酸钙纳米复合材料的制备和表征

以聚乙二醇磷酸酯1000为表面处理剂, 采用碳化法合成了方解石型碳酸钙纳米粒子, 进一步制备了聚对苯二甲酸乙二醇酯/碳酸钙纳米复合材料. 采用透射电子显微镜(TEM)、 X射线衍射(XRD)、 傅里叶变换红外光谱(FTIR), 场发射扫描电子显微镜(FESEM)和热重分析(TGA)对样品进行了分析. 结果表明, 聚乙二醇磷酸酯1000成功地修饰到碳酸钙的表面, 并得到平均直径为60 nm, 形貌为立方体的纳米碳酸钙晶体. 与碳酸钙(空白)样品相比, 表面处理碳酸钙的复合材料表现出更好的分散性和热稳定性. 采用Friedman方法计算了复合材料热分解的活化能. 聚对苯二甲酸乙二醇酯、 聚对苯二甲酸乙二醇酯/空白碳酸钙和聚对苯二甲酸乙二醇酯/表面处理碳酸钙的活化能分别为200.58, 214.86和219.50 kJ/mol, 进一步说明了表面处理碳酸钙更好地改善了聚对苯二甲酸乙二醇酯的热稳定性.     

去氢枞酸异丙醇胺衍生物的合成及其细胞毒性评价

为了寻找高效的抗肿瘤活性化合物,设计合成了一系列去氢枞酸异丙醇胺类化合物,利用IR、NMR和MS对其结构进行表征。采用噻唑蓝(MTT)法评价了目标化合物对四种不同肿瘤细胞T24(人膀胱移行癌细胞)、HepG2(人肝癌细胞)、SK-OV-3(人卵巢癌细胞)、A549(人肺癌细胞)和LO2(人正常肝细胞)的抗增殖活性。结果表明,部分化合物对肿瘤细胞的抑制作用优于阳性对照顺铂。其中,化合物3d对四种细胞株表现出最好的抗增殖效果,IC₅₀值分为8.10±0.28,8.65±0.10,13.21±0.35和8.24±0.42 μmol.L_-1^{。初步机理研究表明},化合物3d使A549细胞周期阻滞在G1/G0期,并诱导A549细胞凋亡,且呈浓度依赖性。     

新型去氢枞酸基磺酰胺类化合物的合成及其生物活性

去氢枞酸与SOCl2反应制得去氢枞酸酰氯(2);芳磺酰氯与乙二胺经N-酰化反应制得N-芳磺酰基乙二胺(4a~4k);在DMAP催化下,2分别与4a~4k经N-酰化反应合成了11个新型的去氢枞酸基磺酰胺类化合物(5a~5k),其结构经1H NMR,13C NMR,IR和ESI-MS表征。生物活性测试结果表明,在用药量为50μg·mL-1时,5a~5k对黄瓜枯萎病菌、苹果轮纹病菌、番茄早疫病菌、花生褐斑病菌和小麦赤霉病菌有一定的抑菌活性,其中去氢枞酸基间甲基苯磺酰胺(5c)对番茄早疫病菌的杀菌活性最佳,抑制率为73.6%;在用药量为100μg·mL-1时,大部分化合物对油菜的胚根生长有一定抑制作用,其中去氢枞酸基对甲氧基苯磺酰胺(5d)的抑菌活性最佳,抑菌率为57.1%。     

Synthesis and characterization of novel biodegradable unsaturated poly(ester amide)/poly(ethylene glycol) diacrylate hydrogels

A series of novel biodegradable hydrogels were designed and synthesized from four types of unsaturated poly(ester amide) (UPEA) and poly(ethylene glycol) diacrylate (PEG‐DA) precursors by UV photocrosslinking. These newly synthesized biodegradable UPEA/PEG‐DA hydrogels were characterized by their gel fraction (G_f), equilibrium swelling ratio (Q_eq), compressive modulus, and interior morphology. The effect of the precursor feed ratio (UPEAs to PEG‐DA) on the properties of the hydrogels was also studied. The incorporation of UPEA polymers into the PEG‐DA hydrogels increased their hydrophobicity, crosslinking density (denser network), and mechanical strength (higher compressive modulus) but reduced Q_eq. When different types of UPEA precursors were coupled with PEG‐DA at the same feed ratio (20 wt %), the resulting hydrogels had similar Q_eq values and porous three‐dimensional interior morphologies but different G_f and compressive modulus values. These differences in the hydrogel properties were correlated to the chemical structures of the UPEA precursors; that is, the different locations of the >C?C< double bonds in individual UPEA segments resulted in their different reactivities toward PEG‐DA to form hydrogels. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3932–3944, 2005     

Synthesis and characterization of poly(acrylic acid) stabilized cadmium sulfide quantum dots

Cadmium sulfide (CdS) nanoparticles (NPs) capped with poly(acrylic acid) (PAA) were prepared in aqueous solutions from Cd(NO3)2 and Na2S. Influence of the COOH/Cd ratio (0.8-12.5), reaction pH (5.5 and 7.5), and PAA molecular weight (2100 and 5100 g/mol) on the particle size, colloidal stability, and photoluminescence were investigated. A Cd/S ratio of <1 causes ineffective passivization of the surface with the carboxylate and therefore results in a red shift of the absorption band and a significant drop in photoluminescence. Therefore, the Cd/S ratio was fixed at 1.1 for all experiments studying the mentioned variables. PAA coating provided excellent colloidal stability at a COOH/Cd ratio above 1. Absorption edges of PAA-coated CdS NPs are in the range of 460-508 nm. The size of the NPs increases slightly with increasing PAA molecular weight and COOH/Cd ratio at pH 7.5. It is demonstrated that there is a critical COOH/Cd ratio (1.5-2) that maximizes the photoluminescence intensity and quantum yield (QY, 17%). Above this critical ratio, which corresponds to smaller crystal sizes (3.7-4.1 nm) for each reaction set, the quantum yield decreases and the crystal size increases. Moreover, CdS NPs prepared at pH 7.5 have significantly higher QY and absorb at lower wavelengths in comparison with those prepared at pH 5.5. Luminescence quenching has not been observed over 8 months.     

Synthesis and characterization of poly(ethylene glycol) grafted poly(L-lactide)

Poly(ethylene glycol) grafted poly(L -lactide) was prepared by ring opening polymerization of L -lactide and epoxy-terminated poly(ethylene glycol) methyl ether (PEGME). Stannous octoate and Al(Et)₃·0.5 H₂O were tested as polymerization catalysts, and Al(Et)₃·0.5 H₂O was found to be more effective for the ring-opening of the epoxy group of the modified PEGME monomer. The synthesized polymers were characterized by NMR and the efficiency of the incorporation of epoxy-terminated PEGME in the copolymer was determined.     

The synthesis and characterization of monodisperse poly(acrylic acid) and poly(methacrylic acid)

A number of polyacrylic (PAA) and polymethacrylic (PMAA) acids have been synthesized by living anionic polymerization of the monomeric tert-butyl esters followed by subsequent hydrolysis of the corresponding polyesters. The necessary precautions were taken in order to assure good molecular weight control, as well as high yields in the polymerization reactions. The intermediate and final polymers were characterized by gel permeation chromatography and NMR-H¹ spectrometry.     

Synthesis and characterization of poly(ethylene glycol) derivatives

Five general routes for the preparation of polyoxyethylene [generally referred to as poly(ethylene glycol) or PEG] derivatives are described. These routes are (1) nucleophilic displacements with the alkoxide of PEG, (2) nucleophilic displacement on PEG–tosylate, –mesylate, or –bromide, (3) reductive amination of PEG–aldehyde, (4) reductive amination of PEG–amine, and (5) nucleophilic displacements on the s-triazine derivatives prepared from s-triazine trichloride (cyanuric chloride) and PEG. Eighteen derivatives are prepared and potential applications to catalysis, cell purifications, and other areas are discussed briefly.     

Molecular structure and dynamics of poly(methacrylic acid) and poly(acrylic acid) complexes with dodecyl-substituted poly(ethylene glycol)

The molecular dynamics and the structure of molecular complexes formed by micelles of dodecyl-substituted poly(ethylene glycol) with poly(methacrylic acid) and poly(acrylic acid) in aqueous solutions were studied by viscosimetry, pH measurement, and electron spin resonance spin-probe techniques. At low surfactant concentrations, the conformation of the complex is a compact globule. The local mobility of surfactant molecules in such a complex is much slower than that in the free micelle. At high surfactant concentration, the nonionic micelles and polyacids form hydrophilic associates. The associates have the conformation of extended coils. In an associate, a major part of the micellar poly(ethylene glycol) groups is free. The local mobility of the micellar phase depends on the number of micelles involved in an associate. The mobility of surfactant molecules is slower in the complexes of poly(methacrylic acid) than in the complexes of poly(acrylic acid).     

Synthesis of new poly(ethylene glycol)-block-poly(ester sulfide) dendrimers

The design and synthesis of novel copolymers that consist of a linear polyoxyethylene block and a dendrimeric poly(ester-sulfide) block with potential applications in drug delivery are described. The dendrimers bear hydroxyl or acrylate functional groups and were prepared via a divergent approach using readily available methoxypoly(ethylene glycol) (mPEG), acryloyl chloride, and 1-thioglycerol as building blocks. All reactions involved occurred efficiently and purification steps consisted of washing the reaction mixture with aqueous solutions and precipitation of the product in diethyl ether.     

Interaction between pentaethylene glycol n-octyl ether and low-molecular-weight poly(acrylic acid)

The interaction between pentaethylene glycol n-octyl ether (C8E5) and low-molecular-weight poly(acrylic acid) (PAA, M(w)=2000) in aqueous solution has been investigated by various experimental techniques at constant polymer concentration (0.1% w/w) with varying surfactant molality. Spectrofluorimetry, using pyrene as molecular probe, shows (i) the formation of surfactant-polymer aggregates at a surfactant molality (T(1)) lower than the critical micelle concentration (cmc) of C8E5 in water and (ii) the formation of free micelles at a surfactant molality (T(2)) slightly higher than the cmc. Fluorescence quenching measurements indicate that the presence of PAA induces a lowering of the C8E5 aggregation number. Calorimetry confirms spectrofluorimetric evidence; in addition, it shows the presence of weak interactions below T(1) between monomeric surfactant molecules and the polymer chains. Tensiometry shows that, above T(1), only a low fraction of surfactant molecules interact with the polymer and that free micelle formation occurs before polymer saturation. The peculiarities of the interaction between surfactants and low-molecular-weight polymers have been discussed.     

Preparation and characterization of poly(acrylic acid)-based nanoparticles

The present investigation describes the synthesis and characterization of nanoparticles based on poly(acrylic acid) (PAA) intramolecularly cross-linked with diamine, 2,2′-(ethylenedioxy)bis(ethylamine), using water-soluble carbodiimide. The aqueous colloid dispersions of nanoparticles were clear or mildly opalescent depending on the ratio of cross-linking, pH of the solution, and the molecular weight of PAA, finding consistent with values of transmittance between 3% and 99%. The structure was determined by nuclear magnetic resonance spectroscopy, and the particle size was identified by dynamic light scattering (DLS) and transmission electron microscopy (TEM) measurements. It was found that particle size depends on the pH, and at a given pH, it was caused by the ratio of cross-linking and the molecular weight of PAA. Particle size measured by TEM varied in the range of 20 and 80 nm. In the swollen state, the average size of the particles measured by DLS was in the range of 35–160 nm.