Cd Te-QDs/g-C_3N_4的合成及其高效可见光光催化产氢研究

CdTe量子点在可见光下具有优异的光催化制氢活性,将CdTe量子点修饰到石墨相氮化碳(g-C_3N_4)表面可以进一步提高其产氢活性。采用一步水热法合成了CdTe QDs/g-C_3N_4复合光催化剂,并用XRD、TEM、DRS、FT-IR和PL对其进行分析。在以CoCl_2为助催化剂和抗坏血酸(H_2A)为牺牲剂的条件下,得到的复合光催化剂在可见光照射下比纯CdTe QDs和gC_3N_4表现出更高的产氢活性。其中质量分数为20%CdTe QDs/g-C_3N_4的复合材料的H2生成量为4. 8 mmol,是纯CdTe QDs的2. 4倍。     

P(AA-co-AMPS)/Kaolin复合高吸水树脂的制备及结构性能研究

以丙烯酸(AA)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)和高岭土(Kaolin)为原料,采用溶液聚合法分别制备出聚丙烯酸(PAA)高吸水树脂、聚(丙烯酸-co-2-丙烯酰胺基-2-甲基丙磺酸)(P(AA-co-AMPS))高吸水树脂、P(AA-co-AMPS)/Kaolin复合高吸水树脂,并通过傅里叶变换红外光谱、扫描电镜、X射线衍射等测试方法对其结构与性能进行表征。结果表明:Kaolin与P(AA-co-AMPS)高吸水树脂之间为物理共混;PAA高吸水树脂、P(AA-co-AMPS)高吸水树脂和P(AA-co-AMPS)/Kaolin复合高吸水树脂的吸水倍率分别为231,323,357 g/g,吸盐水倍率分别为35.6,64.1,66.4 g/g,保水率分别为51.3%,55.6%,57.9%,凝胶形变量分别为3.75,4.10,2.23 mm;树脂的吸水速率由小到大依次为PAA高吸水树脂、P(AA-co-AMPS)高吸水树脂、P(AA-co-AMPS)/Kaolin复合高吸水树脂。     

含CdTe量子点的荧光聚合物和含芘丁酸的荧光聚合物的合成、表征及荧光共振能量转移

报道了一种室温下制备CdTe量子点-聚合物纳米荧光聚合物的方法。首先,使用巯基乙酸(TGA)作为稳定剂在水相中合成CdTe量子点,通过十六三甲基溴化铵(CTAB)将其转移进有机相中。使用N,N-二环己基碳二亚胺(DCC)作为脱水剂将量子点挂接到侧链含有羟基的聚丙烯酸酯(CPA)上。该荧光聚合物CdTe-CPA在室温下合成,能够促进碲化镉量子点-聚合物复合物的荧光性能和稳定性。我们还通过相同的方法,将1-芘丁酸(PBA)连接到聚丙烯酸酯侧链上合成了另一种荧光聚合物P-CPA。对产物通过傅里叶变换红外光谱(FI-IR)、凝胶渗透色谱(GPC)、差示扫描量热(DSC)、透射电镜(TEM)及荧光光谱进行表征。此外还研究了P-CPA和CdTe-CPA间的荧光共振能量转移(FRET)。从吸收和荧光发射光谱得到的数据表明,在二氯甲烷溶液中,从P-CPA到CdTe-CPA间发生了荧光共振能量转移。     

ZnS/PAA纳米复合材料的制备及发光性能研究

以氯化锌、硫化钠及丙烯酸(AA)为原料,偶氮二异丁氰(AIBN)为引发剂,采用原位一步法合成制备ZnS/PAA纳米复合材料。利用X-射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、红外光谱仪(IR)、紫外-可见光谱仪(UV-Vis)、荧光光谱(PL)研究了ZnS/PAA的结构、形貌组成,并研究了反应时间、反应温度及有机单体用量对目标产物发光性能的影响。结果表明,反应温度、反应时间以及单体的量都对ZnS/PAA纳米复合材料的发光性能有影响。合成ZnS/PAA的最佳试验条件:单体AA的体积用量4mL,反应温度50℃,反应时间4h,此时ZnS/PAA纳米复合材料有最优的发光性能。     

P(AA-AMPS)/PVA复合吸水树脂的制备

以丙烯酸(AA)、聚乙烯醇(PVA)为主要原料,通过正交试验确定了PAA/PVA互穿网络高吸水树脂最佳合成工艺,在此基础上以2-丙烯酰胺-2-甲基丙磺酸(AMPS)为第三种原料对其进行复合化改性,通过溶液聚合法制备了P(AA-AMPS)/PVA复合吸水树脂,用红外光谱仪(FTIR)、X-射线衍射分析仪(XRD)和扫描电镜(SEM)对其结构进行表征。结果表明:n(AA)/n(PVA)为4.5,引发剂用量为0.35%,交联剂用量为0.1%,中和度为55%,反应温度为70℃,w(AMPS)为3%时P(AA-AMPS)/PVA复合吸水树脂吸水率最佳。FTIR、XRD和SEM结果表明AA、AMPS和PVA已经聚合,得到目标结构。     

碲化镉-还原氧化石墨烯复合物的合成与表征及光催化产氢性能的研究

采用溶剂热一锅法,合成了系列碲化镉-还原氧化石墨烯复合物CdTe-(RGO)_n(n=0.5, 1, 2, 4,7,n是反应前氧化石墨烯(GO)相对于CdCl_2·2.5H_2O的质量分数)。通过紫外吸收光谱、荧光发射光谱、傅里叶红外光谱、透射电子显微镜和X-射线衍射对它们迚行了表征。此外,选用抗坏血酸作为牺牲电子给体,在水溶液中构建了基于CdTe量子点和RGO的有效光催化产氢体系。相比于纯的CdTe量子点,引入RGO作为电子传输基质,有助于体系光催化放氢的产生。同时,在对比系列复合物CdTe-(RGO)_n(n=0.5, 1, 2, 4, 7)的光催化产氢性能后发现CdTe-(RGO)_1显示出最高的光催化活性。这一现象表明RGO的含量和CdTe-(RGO)_n光催化产氢活性具有相关性,合适负载量的RGO对于优化CdTe-(RGO)_n体系的光催化放氢性能具有重要的意义。     

含砜基聚酰亚胺的合成及其中空纤维膜的制备（英文）

以4,4'-(六氟异丙烯)二酞酸酐(6FDA)与4,4'-双(4-氨基苯氧基)二苯砜(BAPS)为反应单体,以N-甲基-2-吡咯烷酮(NMP)为溶剂,合成了聚酰胺酸(PAA),将PAA溶液采用流延成膜的方法制备成薄膜;另外,将PAA溶液采用干-湿法纺丝工艺制得PAA中空纤维膜,再将PAA薄膜及其中空纤维膜在300℃左右的高温热环化制得6FDA-BAPS型聚酰亚胺(PI)膜。研究了6FDABAPS型PI及其中空纤维膜的结构与性能。结果表明:所合成的6FDA-BAPS型PI为目标产物,其在NNP、N,N-二甲基乙酰胺、四氢呋喃中具有良好的溶解性能。6FDABAPS型PI中空纤维膜外皮层致密、支撑层疏松多孔,该中空纤维膜具有较高的热学性能和力学性能,在氮气氛围中热失重5%的温度为511℃,断裂强度为26.5 MPa。     

用于分离纯化组氨酸标签蛋白质的磁性复合纳米材料的制备

采用溶剂热法制备Fe_3O_4纳米粒子,通过MPS和聚丙烯酸修饰,使其表面羧基化,再与NTA-Ni⁽²⁺⁾螯合,制备Fe_3O_4/MPS/PAA/NTA-Ni(2+)螯合,制备Fe_3O_4/MPS/PAA/NTA-Ni⁽²⁺⁾磁性复合纳米粒子。利用透射电镜、激光粒度仪、红外光谱进行表征。结果表明,Fe_3O_4/MPS/PAA/NTA-Ni(2+)磁性复合纳米粒子。利用透射电镜、激光粒度仪、红外光谱进行表征。结果表明,Fe_3O_4/MPS/PAA/NTA-Ni⁽²⁺⁾磁性复合纳米粒子的形貌为球形,且较为分散,其平均水合粒径为440 nm,Zeta电位为-15.8 mV,红外光谱证实了其化学结构。对组氨酸标签蛋白的分离能力为15.6μg蛋白质/mg磁性材料,说明此金属螯合吸附剂对组氨酸标签蛋白的选择性吸附有一定的意义。     

巯基丙酸还原TeO_2水相一步法合成CdTe/ZnTe核壳型量子点

以TeO2为碲源,巯基丙酸(MPA)为稳定剂和还原剂,采用微波辅助加热法一步合成水溶性CdTe/ZnTe核壳结构的半导体量子点。考察了Cd/Zn反应物配比及MPA用量对CdTe/ZnTe量子点性能的影响,并用紫外、荧光光谱、高分辨透射电子显微镜(HRTEM)、X射线粉末衍射(XRD)光谱和EDX电子能谱对CdTe/ZnTe进行了表征。结果表明,在不需要另加NaBH4的条件下,同样能合成水溶性的CdTe/ZnTe量子点,且该核壳结构的CdTe/ZnTe量子点比单一的CdTe量子点具有更高的荧光量子产率。     

长链聚酰胺酸的缩聚动力学研究

以长链二胺4，4’-二(4-氨基苯氧基)二苯砜(BAPS)为单体，在N，N'-二甲基甲酰胺(DMF)中分别与3种二酐于室温下反应，合成了3种长链聚酰胺酸(PAA)。利用GPC研究了PAA相对数均聚和度(Xn)及其分布随缩聚时间的变化关系。结果表明：该反应为自催化逐步缩聚反应，反应级数为三级；在初始阶段，缩聚速率常数随二酐电子亲和性(EA)的递增而增加。     

Novel approach for attapulgite/poly(acrylic acid) (ATP/PAA) nanocomposite microgels as selective adsorbent for Pb(II) Ion

A novel approach was developed for the preparation of the attapulgite/poly(acrylic acid) (ATP/PAA) nanocomposite microgels via the “one-pot” inverse suspension radical polymerization of acrylic acid (AA) with the multi-functionalized attapulgite nanorods (org-ATP) as the sole crosslinker. The parameters of the feeding ratio of the functional attapulgite (org-ATP) nanorods and AA (org-ATP/AA), oil (liquid paraffin)–water ratio, and feeding ratios of dispersing agent (sodium dodecyl benzene sulfonate (SDBS)) and initiator (ammonium persulfate (APS)) were optimized via 4-Variable 3-Level Orthogonal experiments. Under the optimized preparation condition, more than 85% of the monomer AA had been grafted onto the org-ATP nanorods to form the 3-dimensional network of the ATP/PAA nanocomposite microgel. The ATP/PAA nanocomposite microgel exhibited better mechanical stabilities (resistance to pressure and resistance to agitation) and selective adsorption to heavy metal ions, especially to Pb²⁺. The adsorbed Pb²⁺ ion could be completely eluted with HCl solution. The better mechanical stability and regeneration make it potential adsorbent for the heavy metal contaminated water.     

Study on superabsorbent composites. XXI. Synthesis,characterization and swelling behaviors of chitosan‐g‐poly(acrylic acid)/organo‐rectorite nanocomposite superabsorbents

A novel chitosan‐g‐poly(acrylic acid)/organo‐rectorite (CTS‐g‐PAA/OREC) nanocomposite superabsorbent was synthesized by aqueous polymerization using N, N′‐methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. Rectorite was organified with four different degree of hexadecyltrimethyl ammonium bromide, and the organification of rectorite was proved by FTIR and XRD. The effect of organification degree of rectorite on water absorbency of CTS‐g‐PAA/OREC with different organo‐rectorite content was investigated. The swelling behaviors in distilled water and various pH solutions were also studied. The results from IR spectroscopy and XRD data show that acrylic acid had been grafted polymerization with chitosan and organo‐rectorite and formed nanocomposite. Introducing organo‐rectorite into the CTS‐g‐PAA polymeric network can improved water absorbency and swelling rate of CTS‐g‐PAA/OREC. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and property characterization of PAA/Fe3O4 nanocomposite

PAA/Fe₃O₄ nanocomposites were prepared by mixing nano-Fe₃O₄ and polyacrylic acid (PAA) ethanol solution and then evaporating the solvent. The materials were characterized by transmission electron microscope (TEM), Fourier transform infrared spectroscope (FTIR), thermogravimetry analysis (TGA), dynamic ultra-micro hardness tester (DUMHT) and superconducting quantum interference device (SQUID) magnetometer. Results showed that PAA coordinated with nano-Fe₃O₄ to form a cross-linking structure. The presence of nano-Fe₃O₄ enhanced the thermal stability of the nanocomposite. The elasticity and hardness of the nanocomposite increased, and the indentation depth reduced with the increase of Fe₃O₄ content in the composites. The nanocomposites showed superparamagnetic properties at 300 K. Translated from Acta Scientiarum Naturalium Universitatis Sunyatseni, 2006, 45(5): 47–50 [译自: 中山大学学报 (自然科学版)]     

均聚物调控的PS-b-P4VP薄膜的微相分离形貌

分别以聚丙烯酸(PAA)和聚氧化乙烯(PEO)与苯乙烯与4-乙烯基吡啶二嵌段共聚物(PS-b-P4VP)进行溶液共混并且旋涂成膜,采用原子力显微镜(AFM)研究了这两种均聚物对PS-b-P4VP薄膜微相分离形貌的调控作用。结果表明,PAA与P4VP链段之间强烈的氢键作用使得P4VP链段对PS链段的热力学排斥作用增强,当PAA质量分数为10%时,PS分散相区以规则的柱体垂直分布于由P4VP/PAA链段相互溶解所形成的连续相基体中。对于PS-b-P4VP/PEO共混体系,共混薄膜形成了PEO/P4VP分散相以柱状形态垂直分布在以PS链段聚集区为薄膜连续相基体中的微相分离形貌,由于PS链段无法在PEO/P4VP柱状微区上方形成覆盖,导致共混薄膜表面出现许多孔洞,孔洞底部伴有PEO链段部分结晶形成的锥状突起。随PEO含量增加,孔洞直径增大,孔洞底部的锥状突起也增大。     

An inorganic cross-linked quadruple shape memory hydrogel with high mechanical performance

Shape memory hydrogels (SMHs) have been the subject of great interest in recent years. However, there were few reports on the simultaneous multiple shape memory and high mechanical performance. Therefore, a novel nanocomposite (NC) hydrogel poly (acrylic acid)/Chitosan/ Laponite (PAA/CS/Laponite) was developed by using Laponite as physical cross-linker. In order to achieve three temporary shapes, the PAA/CS/Laponite was soaked in iron chloride hexahydrate (FeCl₃), sodium hydroxide (NaCl) and sodium hydroxide (NaOH) respectively to (a) form metal coordination; (b) gain the chains entanglement of chitosan; (c) get the microcrystalline structure of chitosan. The maximum shape fixity ratio of PAA/CS/Laponite can reach 100% in 1 minute and it can be restored its original shape within 5 minutes. Moreover, PAA/CS/Laponite showed excellent mechanical performance. The maximum tensile and compressive strengths were 0.73 MPa and 13.1 MPa. By comparison with PAA/CS obtained from our previous work, the tensile strength, elongation at break and compressive strength increased by 2.21 times, 1.46 times, and 3.26 times respectively. Scanning electron microscopy (SEM) showed that the obtained sample has uniform honeycomb network structures which can effectively explain why the gel has strong mechanical performance. These characteristics make PAA/CS/Laponite have huge application potential in reality.     

Enhancing the adsorption affinity of cellulose acetate film toward cationic dye by incorporating Cloisite 30B grafted with polyacrylic acid

Cellulose acetate (CA) is known for its low adsorption affinity toward dyes, hence this study aims to improve its adsorption affinity toward cationic dyes by introducing Cloisite 30B grafted with polyacrylic acid (C30B-g-PAA). C30B-g-PAA was synthesized by grafting polyacrylic acid (PAA) onto Cloisite 30B (C30B) using in-situ reversible addition fragmentation chain transfer (RAFT) polymerization. Different weight ratios of unmodified (raw) and modified (C30B-g-PAA) C30B (0, 25, and 50 wt%) were incorporated into CA matrices to prepare a series of CA nanocomposite films. The results showed that the adsorption affinity of the prepared nanocomposite films increased toward cationic methylene blue (MB) dye with incorporating either unmodified or modified C30B, but a significant improvement was observed with the incorporating C30B-g-PAA with a maximum adsorption capacity of 53 mg/g for a load of 50 wt%. This indicates that the surface modification of C30B with PAA was effective in enhancing the adsorption efficacy of CA. The kinetic and isotherm studies showed that the adsorption behavior of CA nanocomposite film with 50 wt% of C30B-g-PAA followed pseudo-second-order and Langmuir isothermal model. Regeneration study showed good reusability of CA nanocomposite film with 50 wt% of C30B-g-PAA. These results demonstrate that the nanocomposite film with 50 wt% of C30B-g-PAA can be used as a highly efficient, easy to separate, and reusable adsorbent material to remove MB dye from wastewater.     

Temperature-responsive multilayered micelles formed from the complexation of PNIPAM-b-P4VP block-copolymer and PS-b-PAA core–shell micelles

Multilayered micelles with a polystyrene (PS) core, a swollen poly(acrylic acid) (PAA)/poly(4-vinyl pyridine) (P4VP) complex shell and a poly(4-vinyl pyridine)-block-poly(isopropyl acryl amide) (P4VP-b-PNIPAM) block-copolymer corona was synthesized by complexation between PNIPAM₅₃-b-P4VP₁₀₉ block-copolymers and the PS₁₂₀-b-PAA₄₇ diblock-copolymer core–shell micelles in ethanol due to the hydrogen bonding between the AA units and 4VP units. The surface of the micelle has been modified and a temperature sensitive block PNIPAM was introduced into the corona of the micelles. After being dialyzed against acidic water, PNIPAM corona would collapse onto the PAA/P4VP shell and the excessive P4VP shell would extend into the acidic solution to form the corona reversed micelles when the micelle aqueous solution was heated to 45 °C. The whole process was performed using dynamic light scattering (DLS), static light scattering (SLS), atom force microscope (AFM) and nuclear magnetic resonance (NMR).     

Surfactant‐dispersed carbon black in polyimide nanocomposites: Spectroscopic monitoring of the dispersion state in the polymer matrix

The effects of an anionic surfactant on the dispersion of carbon black (CB) for the purpose of forming conducting composite films were examined with ultraviolet–visible (UV–vis) absorption spectroscopy. To obtain a good dispersion and size reduction of aggregated CB in a polymer matrix, sodium dodecyl sulfate (SDS), used as a surfactant, was introduced into a CB suspension. A set of concentrations with various ratios of CB to SDS (ranging from 1 : 0.4 to 1 : 10) was established before mixing with poly(amic acid) (PAA), a precursor of pyromellitic dianhydride and oxydianiline, was performed. The CB/PAA solution mixtures were submerged under an ultrasonic bath for several hours, then cast onto dry plate glasses, and finally subjected to thermal imidization to produce CB/polyimide (PI) nanocomposite films with various CB weight fractions ranging from 0.025 to 0.50 wt %. A method for evaluating the absorbance at 500 nm of the CB/PI nanocomposite films was established. The absorbance of CB/PI nanocomposite samples of various thicknesses was also normalized to get rid of the effects of the different thicknesses. UV–vis spectra showed that the minimum weight ratio of CB to SDS in the nanocomposite films that achieved well‐dispersed CB and still had transparent properties was 1 : 2.0. Transmission electron microscopy demonstrated that CB was dispersed homogeneously in the PI matrix, and the size of the aggregated CB was affected by the amount of the surfactant. The dielectric properties of the nanocomposite films without the surfactant increased by approximately 2 orders of magnitude with an increasing mass weight fraction of CB and decreased when the surfactant was added. The surfactant also reduced the tensile strength of the CB/PI nanocomposites when the CB/SDS ratio was higher than 1 : 2.0. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Change in Orientation of Polyacrylic Acid and Chitosan Networks by Imprintment of Gold Nanoparticles

ABSTRACT

Herein, gold nanoparticles (Au Nps) imprinted polyacrylic acid/chitosan (PAA/CS) nanocomposite hydrogels are designed by in situ polymerization technique. The change in crystallite size and d-spacing is established from X-ray diffraction study. It is interesting to notice that the layered morphology of PAA/CS/Au nanocomposite hydrogel is achieved from field emission scanning electron microscopy due to entanglement of polymeric chains by imprintment of Au Nps. The orientations of polymeric chains reveal the enhancement in pH-responsive swelling percentage and prolong water holding capacity of PAA/CS/Au nanocomposites. Biodegradation of the as-synthesized material is studied from which the antimicrobial activity of Au Nps is predicted.