癸二酸改性丁二酸丁二醇基聚酯材料的结晶性能和降解性能

以癸二酸、丁二酸为二元酸,丁二醇为二元醇,通过熔融共聚的方式合成了聚(癸二酸丁二醇酯丁二酸丁二醇酯)无规共聚物(SE10)和聚丁二酸丁二醇(PBS),并通过酶解实验研究了相对分子质量、结构、表面形态的变化。通过红外光谱、差示量热扫描仪、偏光显微镜、凝胶色谱和扫描电镜对二者降解前后性能进行了研究,相比PBS,SE10晶体直径较小,晶体结构形态变模糊,结晶度由68.0%下降为45.7%,熔点由115.23℃下降为92.40℃。90d后SE薄膜的质量损失率达到63%,珚Mw由34700降为11500,而PBS质量损失率为27%,珚Mw由49000降为33000。表明癸二酸的引入降低了PBS的结晶性能,提高了其降解性能。     

聚乳酸-聚丁二酸丁二醇酯嵌段共聚体系对聚乳酸熔体流变性能的影响

采用未封端的聚乳酸(PLA1)和聚丁二酸丁二醇酯(PBS)通过大分子链末端直接脱水酯化反应制备聚乳酸-聚丁二酸丁二醇酯嵌段共聚体系(LB),并对比研究LB体系及纯PBS两种改性剂对封端聚乳酸(PLA)熔体流变性能的影响。流变测试结果证明,LB或PBS的添加均使PLA的储能模量有较明显的提高。但当改性剂的含量相同时,LB对PLA熔体流变性能的提高幅度明显高于PBS,这可能是因为在LB共聚体系中除传统的"海岛"结构外还形成了新的PLA1-PBS"核壳"结构。     

聚乙二醇-聚丁二酸丁二醇酯-聚乙二醇嵌段共聚物的合成与表征EI北大核心CSCD

以1,4-丁二酸(SA)和过量的1,4-丁二醇(BD)为反应物,通过熔融缩聚制备了羟基封端聚丁二酸丁二醇酯齐聚物(OH-PBS-OH),以甲氧基聚乙二醇(Me OPEG)与丁二酸酐进行半酯化得到含端羧基的预聚物,再用二氯亚砜对预聚物进行活化,得到含酰氯端基的预聚物(Me OPEG-COCl);以Me OPEG-COCl与OH-PBS-OH为反应物,通过溶液法合成聚乙二醇-聚丁二酸丁二醇酯-聚乙二醇(Me OPEG-PBS-PEGOMe)嵌段共聚物。利用红外光谱、核磁共振、差示扫描量热、广角X射线衍射、偏光显微镜等手段对共聚物的结构、结晶性能和酶降解性能进行研究。结果表明,Me OPEG-PBS-PEGOMe嵌段共聚物中,聚乙二醇(PEG)链段的引入未改变聚丁二酸丁二醇酯(PBS)链段的晶体结构,但结晶形态由球晶转变为麦穗状晶体;同PBS比较,Me OPEG-PBS-PEGOMe嵌段共聚物的结晶速率降低,酶降解速率加快。     

脂肪族聚酯结晶特性与分子结构的关系

用差示扫描量热法(DSC)和修正的Avrami方程研究了聚丁二酸乙二醇酯(PES)、聚丁二酸丁二醇酯(PBS)、聚丁二酸己二醇酯(PHS)、聚己二酸己二醇酯(PHA)和聚癸二酸己二醇酯(PHSe)的非等温结晶动力学,得到了脂肪族聚酯的Avrami指数、结晶速率常数、结晶活化能和过冷度等结晶动力学参数.结果表明,脂肪族聚...     

聚乙二醇-聚丁二酸丁二醇酯-聚乙二醇嵌段共聚物的合成与表征

以1,4-丁二酸(SA)和过量的1,4-丁二醇(BD)为反应物,通过熔融缩聚制备了羟基封端聚丁二酸丁二醇酯齐聚物(OH-PBS-OH),以甲氧基聚乙二醇(Me OPEG)与丁二酸酐进行半酯化得到含端羧基的预聚物,再用二氯亚砜对预聚物进行活化,得到含酰氯端基的预聚物(Me OPEG-COCl);以Me OPEG-COCl与OH-PBS-OH为反应物,通过溶液法合成聚乙二醇-聚丁二酸丁二醇酯-聚乙二醇(Me OPEG-PBS-PEGOMe)嵌段共聚物。利用红外光谱、核磁共振、差示扫描量热、广角X射线衍射、偏光显微镜等手段对共聚物的结构、结晶性能和酶降解性能进行研究。结果表明,Me OPEG-PBS-PEGOMe嵌段共聚物中,聚乙二醇(PEG)链段的引入未改变聚丁二酸丁二醇酯(PBS)链段的晶体结构,但结晶形态由球晶转变为麦穗状晶体;同PBS比较,Me OPEG-PBS-PEGOMe嵌段共聚物的结晶速率降低,酶降解速率加快。     

脂肪族聚酯的热稳定性研究

用热失重(TG)和F lynn方法(等转化率方法)研究了聚丁二酸乙二醇酯(PESu),聚丁二酸丁二醇酯(PBSu),聚丁二酸已二醇酯(PHSu),聚癸二酸己二醇酯(PHSe)的热稳定性。结果表明,这些聚酯的热分解温度和分解活化能均随酯基浓度的降低而升高。该研究可对脂肪族聚酯的分子设计、合成和加工工艺提供参考。     

丁二酸乙二醇/丁二酸丁二醇酯比例对聚(丁二酸乙二醇-co-丁二酸丁二醇酯)物理及降解性能的影响

通过熔融缩聚反应合成了聚丁二酸乙二醇酯(PES)、聚丁二酸丁二醇酯(PBS)和它们的共聚酯——聚(丁二酸乙二醇-co-丁二酸丁二醇酯)(P(ES-co-BS)s),对所合成的聚酯进行了一系列的物理性能及酶水解研究.结果表明,在纯PES中掺入BS单元改变了PES的晶体结构、微晶尺寸和结晶度,其中,ES/BS摩尔比为54/46的P(ES-co-BS46)具有最大的微晶尺寸和最低的结晶度.P(ES-co-BS)s共聚酯的断裂伸长率均高于纯PES和PBS.所合成的P(ES-co-BS)s共聚酯的热分解温度均高于290℃,具有良好的热稳定性.利用角质酶对所合成的聚酯进行酶水解测试,水解速率依次为P(ES-co-BS46)>P(ES-co-BS56)>P(ES-co-BS65)>PES>PBS.其中,P(ES-co-BS46)具有较低的熔融温度、结晶度和较高的亲水性能,酶水解速率较快.     

新型液晶共聚酯的合成与表征

设计合成了对苯二甲酸 (4 ,4’ 二甲氧酰基 )二苯酯和间苯二甲酸 (4 ,4’ 二甲氧酰基 )二苯酯 ,并利用红外分析、核磁分析对液晶基元进行了表征。考察了温度和催化剂对液晶基元合成反应的影响。通过熔融酯交换法 ,以液晶基元为聚丁二酸丁二醇酯 (PBS)的共聚组分 ,合成了两个系列的液晶共聚酯。考察了催化剂种类及液晶含量对聚合物分子量的影响 ,并对其进行了表征     

聚(丁二酸丁二醇酯丁二酸环己烷二甲醇酯)的合成与表征

用熔融缩聚法合成了一系列聚(丁二酸丁二醇酯丁二酸环己烷二甲醇酯)的无规共聚物。用FT-IR,1H-NMR,DSC,TGA,XRD及水降解测试等方法表征了材料的结构与性能。通过DSC和TGA分析得到产物的熔点虽然较聚丁二酸丁二醇酯(PBS)有所降低,但是热分解温度却得到了提高;XRD测试结果表明,共聚物的晶体结构并没有发生改变;水降解测试结果表明,共聚物较PBS的降解速率有所提高。     

可完全生物降解塑料的市场化进展

介绍了目前最具有市场前景的3类可完全生物降解塑料的性能(聚羟基脂肪酸酯、聚丁二酸丁二醇酯和聚乳酸)和国内外市场化进展。     

Seed Extract of Psidium guajava as Ecofriendly Corrosion Inhibitor for Carbon Steel in Hydrochloric Acid Medium

The anticorrosion characteristics of the seeds of Psidium guajava (P. guajava) fruits on carbon steel in acid medium were examined with weight loss data and subsequently thermodynamic factors such as heat of adsorption of the inhibitor on the metal surface (Q), change in entropy (△S), change in free energy of the reaction (△G), corrosion rate (CR) and energy of activation for corrosion reaction of carbon steel (E) were also evaluated. Adsorption isotherm was plotted to study the adsorption of the inhibitor on the metal surface with increasing concentration of the inhibitor. The functional groups responsible for inhibition were investigated using Fourier transform infrared (FT-IR) spectra. Electrochemical parameters were evaluated through the potentiodynamic Tafel polarization and impedance spectral studies. Scanning electron microscopy (SEM) micrographs were recorded to investigate the change in surface morphology. The complete study reveals the e?ciency of seed extract of P. guajava as a safe, ecofriendly and alternate corrosion inhibitor for carbon steel in acid medium.     

硝酸表面氧化改性木质活性碳纤维

采用2~14mol/L的硝酸,在23~83℃下,对木质活性碳纤维(WACF)浸渍氧化改性1~8h后,通过Raman、XPS、水吸附和汞吸附等表征表面官能团的结构性能。结果表明,硝酸氧化能力强,可以增加氧原子浓度。酚基、醇基、羟基、羧基官能团随着硝酸浓度增大而增多,酚基和醇基随着浸渍时间的延长而减少,羟基随着浸渍时间的延长而显著增多。WACF表面的石墨化程度随硝酸浓度增大而提高,芯部石墨化程度整体提高但不随浓度梯度的变化而变化。硝酸改性后WACF的水吸附孔容降低,水吸附比表面积显著增加。WACF对HgCl2的吸附量随着硝酸浓度的增大、温度的升高和浸渍时间的延长而增大。以WACF的吸附能力为研究目标,通过对其形貌、晶体结构、表面官能团等进行表征,揭示影响水吸附、汞吸附性能的表面结构特性和化学特性的内在规律,研究结果对WACF功能化利用有指导意义。     

The incorporation of mono- and bi-functionalized multiwall carbon nanotubes in organic photovoltaic cells

We have successfully prepared mono- and bi-functionalized multiwall carbon nanotubes (MWCNT) with thiophene, amine and thiophene-amine groups. The dispersion of nanotubes has been enhanced and stable optimized dispersions in organic solvents were obtained. These functionalized nanotubes have been successfully incorporated into bulk heterojunction (BHJ) organic photovoltaic (OPV) cells with a poly (3-hexyl thiophene) (P3HT) and [6, 6]-phenyl-C(61)-butyric acid methyl ester (PCBM) photoactive blended layer. The incorporation of MWCNT with different functional groups, in the active layer, results in different cell performance with respect to a reference cell. A maximum power conversion efficiency of 2.5% is achieved with the inclusion of thiophene functionalized nanotubes. This improvement in the device performance is attributed to an extension of the exciton dissociation volume and charge transport properties through the nanotube percolation network in P3HT/CNT, PCBM/CNT or both phases. This is believed to be due to more efficient dispersion of the functionalized nanotubes within the photoactive composite layer.     

Self-assembly phenomenon of hydroxyapatite nanocrystals on chondroitin sulfate

Self-assembly phenomenon of hydroxyapatite (HAp) nanocrystals on chondroitin sulfate (ChS) templates was investigated. A HAp/ChS hybrid was synthesized through a precipitation method with a calcium hydroxide suspension and phosphoric acid solution containing the ChS. The preferential alignment of the crystallographic c-axis of the HAp crystals parallel to the long axis direction of the ChS templates was observed to occur with the chemical interactions between the HAp crystals and the functional groups of the ChS. This phenomenon was interpreted by the crystallochemical specific nucleation and growth of the HAp crystals regulated by the pre-organized functional groups of the ChS template. Practical implication may involve a biomimetic artificial bone or cartilage can be made through a precipitation method with suitable bio-organics.     

Modification of oxidized graphite edge surface with poly(vinyl chloride)

An oxidized edge surface of pyrolytic graphite (PG) has been prepared by electrochemical treatment. A thin layer of poly(vinyl chloride) (PVC) was coated on the oxidized edge surface, and the PVC-coated sample heat treated at 300, 400, and 500 °C, respectively. The influence of the PVC coating on the structural change of the oxidized edge surface of PG caused by the heat treatment was studied by laser Raman and Fourier transform-infrared attenuated total reflection spectroscopies. For the electrochemical treatment, the formation of oxygen-containing functional groups proceeds over the edge surface of PG. With increasing degree of oxidation, the functional groups are formed in the following order; hydroxyl groups, carboxyl groups, lactone groups, quinones, and acid anhydrides. Acid anhydrides are formed on the outermost surface and completely eliminated by heat treatment up to 300 °C. The other functional groups remain even after heat treatment up to 500 °C. However, the functional groups are eliminated by the PVC coating, the elimination temperature depending on the type of functional groups: quinones, lactone groups, and carboxyl groups are eliminated at 300, 400, and 500 °C, respectively. PVC coated on the edge surface is found to play an important role in the complete elimination of oxygen-containing functional groups with >C=O through heat treatment at 500 °C.     

Hybrid inorganic-organic adsorbents Part 1: Synthesis and characterization of mesoporous zirconium titanate frameworks containing coordinating organic functionalities

A series of functional hybrid inorganic-organic adsorbent materials have been prepared through postsynthetic grafting of mesoporous zirconium titanate xerogel powders using a range of synthesized and commercial mono-, bis-, and tris-phosphonic acids, many of which have never before been investigated for the preparation of hybrid phases. The hybrid materials have been characterized using thermogravimetric analysis, diffuse reflectance infrared (DRIFT) and 31P MAS NMR spectroscopic techniques and their adsorption properties studied using a 153Gd radiotracer. The highest level of surface functionalization (molecules/nm2) was observed for methylphosphonic acid (～3 molecules/nm2). The level of functionalization decreased with an increase in the number of potential surface coordinating groups of the phosphonic acids. Spectral decomposition of the DRIFT and 31P MAS NMR spectra showed that each of the phosphonic acid molecules coordinated strongly to the metal oxide surface but that for the 1,1-bis-phosphonic acids and tris-phosphonic acids the coordination was highly variable resulting in a proportion of free or loosely coordinated phosphonic acid groups. Functionalization of a porous mixed metal oxide framework with the tris-methylenephosphonic acid (ATMP-ZrTi-0.33) resulted in a hybrid with the highest affinity for 153Gd3+ in nitric acid solutions across a wide range of acid concentrations. The ATMP-ZrTi-0.33 hybrid material extracted 153Gd3+ with a Kd value of 1×10(4) in 0.01 M HNO3 far exceeding that of the other hybrid phases. The unfunctionalized mesoporous mixed metal oxide had negligible affinity for Gd3+ (Kd<100) under identical experimental conditions. It has been shown that the presence of free or loosely coordinated phosphonic acid groups does not necessarily translate to affinity for 153Gd3+. The theoretical cation exchange capacity of the ATMP-ZrTi-0.33 hybrid phase for Gd3+ has been determined to be about 0.005 mmol/g in 0.01 M HNO3. This behavior and that of the other hybrid phases suggests that the surface-bound ATMP ligand functions as a chelating ligand toward 153Gd3+ under these acidic conditions.     

Surface interaction and desorption of trimethyl phosphate from ozonized activated carbon fabric

Trimethyl phosphate (TMP) is a typical simulant of the CWA nerve agents and its adsorption on pristine and ozonized ACF has been studied by FT-IR and ESR spectroscopy. The FT-IR analysis is effective in putting in evidence the strong interaction of TMP with the ACF surfaces through the P = O stretching band shift toward lower frequencies after adsorption. Ozonized ACF ensures a stronger interaction with the adsorbate through the hydrogen bond formation between the adsorbed TMP and the oxygenated functional groups present on carbon surface. At room temperature the ozonized ACF is able to adsorb larger amounts of TMP than the pristine ACF and shows also a better retention of the adsorbate at room temperature. The TGA-FTIR analysis of TMP desorption from both ozonized and pristine ACF has shown that TMP undergoes a partial thermal decomposition into methanol and phosphoric acid above 175°C. The maximum methanol production rate was observed at 250°C in the TMP desorption process from ozonized ACF and at 280°C from TMP desorption from pristine ACF.     

电解液对PAN-基碳纤维电化学改性效果的影响

分别采用磷酸、氢氧化钠和碳酸氢铵3种电解液对PAN-基碳纤维进行电化学改性处理,研究电解液种类对碳纤维电化学改性效果的影响规律.通过酸碱滴定法、原子力显微镜表征和复合材料界面剪切强度(IFSS)测试,分析纤维表面酸性官能团含量、表面形貌及其复合材料界面强度的变化规律.研究结果表明:采用磷酸和氢氧化钠电解液处理时,纤维表面酸性官能团含量随着电流强度的增加先迅速增大而后逐渐减少,电流强度为0.4 A/g时达到最大值;采用碳酸氢铵电解质时,纤维表面酸性官能团含量随着电流强度的增大先缓慢增大而后迅速减少,电流强度为1.4 A/g时达到最大值.针对纤维表面形貌的AFM分析表明,在磷酸和氢氧化钠电解液中处理时,复合材料的IFSS主要受纤维表面刻蚀作用的影响,而采用碳酸氢铵电解液处理时,复合材料的IFSS主要受纤维表面酸性官能团含量的影响.     

Carbon nanotube-DNA nanoarchitectures and electronic functionality

Biological molecules such as deoxyribonucleic acid (DNA) possess inherent recognition and self-assembly capabilities, and are attractive templates for constructing functional hierarchical material structures as building blocks for nanoelectronics. Here we report the assembly and electronic functionality of nanoarchitectures based on conjugates of single-walled carbon nanotubes (SWNTs) functionalized with carboxylic groups and single-stranded DNA (ssDNA) sequences possessing terminal amino groups on both ends, hybridized together through amide linkages by adopting a straightforward synthetic route. Morphological and chemical-functional characterization of the nanoarchitectures are investigated using scanning electron microscopy, transmission electron microscopy, atomic force microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy, and Fourier-transform infrared spectroscopy. Electrical measurements (I-V characterization) of the nanoarchitectures demonstrate negative differential resistance in the presence of SWNT/ssDNA interfaces, which indicates a biomimetic route to fabricating resonant tunneling diodes. I-V characterization on platinum-metallized SWNT-ssDNA nanoarchitectures via salt reduction indicates modulation of their electrical properties, with effects ranging from those of a resonant tunneling diode to a resistor, depending on the amount of metallization. Electron transport through the nanoarchitectures has been analyzed by density functional theory calculations. Our studies illustrate the great promise of biomimetic assembly of functional nanosystems based on biotemplated materials and present new avenues toward exciting future opportunities in nanoelectronics and nanobiotechnology.     

Polymer microspheres with active carboxyl groups: preparation, structure and hydrophilicity

A quantitative research of microspheres, poly(ethylene glycol dimethacrylate-co-acrylic acid) (P(EGDMA-co-AA)) and poly(divinvlbenzene-80-co-acrylic acid) (P(DVB-co-AA)), with active carboxyl groups on surface prepared by distillation-precipitation polymerization was presented in this paper. The loading capacity of active carboxyl group on microspheres which was investigated by titration technique would be increased and the contact angle was decreased following the increase of the feed ratio of acrylic acid (AA) monomer. This phenomenon indicated that the hydrophilicity of particles was mainly determined by the feed ration of hydrophilic AA monomer. However, when the AA fraction was at a fixed level, a slight difference of the loading capacity of carboxyl groups on microsphere surfaces with different crosslinkers existed. The microspheres with EGDMA as crosslinker had a higher loading capacity of carboxyl groups and lower contact angle than those of P(DVB-co-AA) microspheres, which indicated that P(EGDMA-co-AA) microspheres were more hydrophilic than P(DVB-co-AA) microspheres.