原子转移自由基聚合制备ABA型嵌段共聚物

以α，α’－二溴代二甲苯为引发剂，CuBr/2,2‘－联吡啶为催化体系，制备了双溴端基的分子量分布窄的聚苯乙烯（MWD＝1．21）。再以此作为大分子引发剂，实现了甲基丙烯酸甲酯的原子转移自由基聚合，制得了分子量可控且分子量分布窄的ABA型嵌段共聚物，即聚甲基丙烯酸甲酯－b－聚苯乙烯－b－聚甲基丙烯酸甲酯。     

端羟基聚丙烯酸丁酯的合成与表征

以α-溴代异丁酸乙酯为引发剂,采用原子转移自由基聚合(ATRP)合成了分子量为500的聚丙烯酸丁酯。以N-甲基单乙醇胺作为亲核试剂,对带有活性溴端基的聚丙烯酸丁酯进行亲核取代反应,得到了一端带有羟基的聚丙烯酸丁酯。利用红外光谱仪、核磁共振谱仪、凝胶渗透色谱仪等对产物的结构进行表征。结果表明,成功合成了端羟基聚丙烯酸丁酯,且聚合物分子量可控,分子量分布窄(PDI=1.09)。     

甲基丙烯酸异丁酯的低温原子转移自由基聚合

以α-溴代丁酸乙酯(α-EBrB)／硫氰酸亚铜(CuSCN)／N,N′,N′,N″,N五甲基二乙站基三胺(PMDETA)为引发体系,N,N-二甲基甲酰胺(DMF)为溶剂,研究了甲基丙烯酸异丁酯(i—BMA)的低温(30℃)原子转移自由基聚合(ATRP)。考察了催化体系、配比、引发剂用量以及温度对聚合速率、聚合物的分子量及分子量分布的影响。     

缩聚法制备热固性聚乳酸及其力学性能和热稳定性研究

以L-乳酸为单体、季戊四醇为引发剂,采用缩聚法合成了短链四臂星形聚乳酸(4sPLA),随后经不饱和酸酐对其端基改性,合成了含不饱和端基的四臂星形聚乳酸预聚物(M4sPLA),最后通过自由基引发M4sPLA的固化反应制备热固性聚乳酸,重点研究了缩聚时间对预聚物和热固性聚乳酸产物的影响。结果表明:延长缩聚时间可明显提高羟基引发效率和星形聚乳酸的分子量,降低杂质含量,使其分子量分布更窄;随直接缩聚时间的延长,固化产物具有更高的交联密度,经20 h直接缩聚的固化产物具有最好的力学性能、热稳定性以及完善的微观结构。     

高分子量聚L-乳酸的合成和表征

采用丙交酯开环聚合合成聚L-乳酸(PLLA),研究了引发剂用量、聚合时间对聚L-乳酸分子量的影响.采用FTIR、DSC、TG分析方法对聚乳酸的结构和热性能加以表征.研究结果表明通过对聚合时间以及引发剂用量的控制,合成出高分子量聚L-乳酸.FTIR分析结果证实了聚L-乳酸的结构,DSC分析表明合成出的聚L-乳酸玻璃化转变温度为62℃,结晶度达到42.3%;TG分析表明聚L-乳酸热分解温度为299℃.     

端氨基聚乙二醇-聚乳酸嵌段共聚物的合成及表征

以聚乙二醇为原料,采用四步反应,合成了二碳酸二叔丁酯单保护的氨基聚乙二醇(BOC-PEG-NH2);并以DOe-PEG-NH2为引发剂,引发丙交酯开环聚合,得到了叔丁氧基酰胺基聚乙二醇-聚乳酸嵌段共聚物(BOC-PEG-PLA).在三氟乙酸二氯甲烷溶液中,脱去保护基团,得到了端氨基聚乙二醇-聚乳酸嵌段共聚物(NH2-PEG-PLA).采用核磁共振氢谱(1H-NMR)、紫外光度仪(UV)表征各聚合物的结构,由凝胶色谱仪(GPC)测定嵌段共聚物的分子量以及分子量分布.结果表明:合成的氨基引发在无催化剂条件下能够引发丙交酯开环聚合,制得分子量高、分子量分布窄的双亲性共聚物.通过三氟乙酸脱保护得到了端氨基聚乙二醇-一聚乳酸(NH2-PEG-PLA),且对分子量没有影响.     

纳米铜/PMMA-b-PS的超声合成及有序组装

在超声辐射作用下,以α-溴代丙酸乙酯为引发剂,溴化亚铜/2,2-联吡啶为催化体系,通过原子转移自由基聚合(A-TRP)制备了分子链末端含有一个α-溴原子的聚甲基丙烯酸甲酯(PMMA-Br)。以此为大分子引发剂引发苯乙烯单体进行ATRP反应,制得聚甲基丙烯酸甲酯嵌段聚苯乙烯(PMMA-b-PS)共聚物。通过硼氢化钠还原聚合物体系中的溴化亚铜,从而得到纳米铜/PMMA-b-PS复合粒子。红外光谱(FT-IR)和核磁共振(1H-NMR)表征嵌段共聚物的结构;凝胶渗透色谱(GPC)测定了共聚物的相对分子量和多分散系数;X射线光电子能谱(XPS)证明纳米铜和PMMA-b-PS嵌段共聚物中PMMA之间存在一定的相互作用;通过高分辨透射电子显微镜(HTEM)观察到纳米铜具有诱导聚合物组装的现象。     

温度/pH敏感性荧光胶束的制备及性能研究

通过溴乙酰溴与9-氨基吖啶(9-AA)的酰胺化反应,合成了带有2个活性溴原子的新型荧光性引发剂9-AA-Br。核磁共振氢谱(1 H-NMR)测定表明其结构明确。以氯化亚铜(CuCl)/四氮杂十四员大环冠醚(Me6[14]aneN4)为催化体系,由9-AA-Br引发N-异丙基丙烯酰胺(NIPAAm)进行原子转移自由基聚合(ATRP),成功合成了结构明确、分子量可控的双臂型PNIPAAm大分子荧光探针,由紫外分光光度计测得其最低临界溶解温度(LCST)在32℃左右,且随着溶液浓度及聚合物分子量的增加而降低。温度低于LCST时,PNIPAAm大分子荧光探针在溶液中能进行自组装形成胶束,由透射电镜(TEM)观察表明,胶束的大小在500nm左右,该聚合物胶束还具有pH敏感性,在碱性条件下随着pH的增大,荧光发射峰变强。     

原子转移自由基聚合法合成磺基甜菜碱型两性离子均聚物

为了实现两性离子可控聚合,文中以溴异丁酰基-叔丁氧碳基乙二胺(BDBBr)为引发剂,溴化亚铜为催化剂,2,2’-联吡啶(Bpy)为配体,用原子转移自由基法(ATRP)将3-(2-甲基丙烯酰氧乙基二甲胺基)丙磺酸盐(DMAPS)进行聚合,考察了溶剂体系、反应温度和反应时间对聚合反应的影响,用凝胶渗透色谱仪(GPC)测定了分子量和分子量分布。研究结果表明,在良溶剂体系三氟乙醇/异丙醇=20∶1(体积比)和室温30℃条件下,得到目标聚合度Xn=50和Xn=100的磺酸盐两性离子聚合物。反应温度为60℃的聚合物比温度为30℃的聚合物的相对分子质量更低,分子量分布更宽。随着时间的延长,聚合物的相对分子质量有变大且转化率逐渐升高的趋势。     

葡萄糖还原FeBr_3催化下的甲基丙烯酸甲酯原子转移自由基聚合

以葡萄糖为还原剂,FeBr3为氧化剂,通过氧化还原反应,在反应体系中原位生成FeBr2催化剂,以2,2’-联吡啶(bpy)为配位剂,1-溴乙基苯为引发剂,在110℃进行甲基丙烯酸甲酯原子转移自由基聚合。结果表明,聚合反应符合对单体浓度为一级的动力学关系,聚合物分子量随单体转化率呈线性增加,分子量分布较窄,M-w/-Mn在1.17～1.25之间,具有明显的活性聚合特征,并且在有氧的环境下同样能够进行活性聚合,该聚合方法明显优于常规的原子转移自由基聚合和反向原子转移自由基聚合。     

包覆型α-Al_2O_3粉体的制备及表征

以平均粒径为22μm和0.5μm的α-Al2O3粉体为起始原料(以下分别简称Al2O3(C)和Al2O3(F)),分别以聚乙烯亚胺(PEI)和聚甲基丙烯酸铵(APMA)为聚合物电解质,采用非均相凝固法将Al2O3(F)颗粒均匀地包覆在Al2O3(C)粉体表面.重点考察了聚合物电解质的吸附时间、Al2O3(C)/Al2O3(F)的质量比、两种分子量的PEI对包覆型氧化铝粉体制备的影响.当Al2O3(C)/Al2O3(F)的质量比为1∶3,经过分子量约为60 000的PEI处理2 h的Al2O3(C)粉体表面均匀地包覆了Al2O3(F)颗粒(经APMA处理2 h).采用该包覆型粉体制备出片状多孔支撑体,其孔隙率为35.8%,平均孔径为2.9μm,纯水通量为205 m3/(m2.h.MPa).     

Photochemical degradation of 1,3-dichloro-2-propanol aqueous solutions

The photochemical oxidation of 1,3-dichloro-2-propanol (1,3-DCP) was studied by following the target compound degradation, the total carbon removal rate by a total organic carbon (TOC) analyzer and by identifying the oxidation products by gas chromatography-mass spectrometry (GC-MS). The reaction was performed in a batch recycle reactor, at room temperature, using UV radiation provided by a low pressure 12W Hg lamp and H(2)O(2) as oxidant. Chloride ions, formic, acetic and chloroacetic acid were measured by ion chromatography. Apart from the chloride ions and the organic acids, the presence of 1,3-dichloro-2-propanone and chloroacetyl chloride was also detected and a possible pathway is proposed for the degradation of the parent compound. Complete degradation of 1,3-dichloro-2-propanol was achieved and the TOC removal reached as much as 80% at the end of the reaction time. The effect of the initial concentration of hydrogen peroxide was investigated and it was established that higher concentrations of H(2)O(2) slow down the reaction rate. Finally, the effect of the initial concentration of 1,3-DCP was investigated.     

聚乙二醇/纳米氢氧化镍溶胶体系稳定性的研究

以Ni(AC)2为原料,采用改进的溶胶凝胶法制备了PEG6000/纳米Ni(OH)2复合溶胶体系.Zeta电位研究了该溶胶中Ac-对体系稳定性的影响,结合红外光谱确定了稳定溶胶的结构.结果表明,Ac-降低了溶胶的稳定性,而 PEG通过与Ni(OH)2的氢键结合或其他弱的相互作用而改变胶体表面的Zeta电位,并通过空间位阻效应增强胶体稳定性.粘度法确定了溶胶的稳定区域.采用稳定溶胶配方制备的纳米NiO粉体,粒径均匀度、粒子分散性均好于不稳定溶胶配方.PEG6000在纳米材料制备过程中起到了水解控制剂、稳定剂、分散剂的作用.     

微波均相合成Ce_(0.75)Zr_(0.25)O_2粉体及其烧结性

以Ce(NO3)3.6H2O和ZrOCl2.8H2O为原料,以尿素为沉淀剂,利用微波均相法制备Ce0.75Zr0.25O2粉体,采用热分析仪、X射线衍射仪、扫描电子显微镜表征制备的粉体,对制备的粉体压制成型并烧结,用扫描电子显微镜观察烧结体的微观结构。结果表明,合成Ce0.75Zr0.25O2前驱体时加入2倍于Ce3+物质的量的H2O2可以减小固溶体颗粒粒度,降低固溶温度30℃;所制备的固溶体粉体具有良好的烧结性,在1 550℃得到烧结体的相对密度达99.57%。     

两嵌段共聚物PMMA-b-PHEMA的合成与表征

采用分步法合成了两嵌段共聚物聚甲基丙烯酸甲酯-b-聚甲基丙烯酸-2-羟乙酯.首先以AIBN为引发剂,FeCl<,3>/PPh<,为>催化体系,通过甲基丙烯酸甲酯(MMA)的反向原子转移自由基聚合,得到端基含Cl的聚合物PMMA-Cl,其分子量分布为1.36;然后以此为大分子引发剂,FeCl<,2>/PPh<,3>为催化...     

PT／SiO2精细复合材料的制备及其特性

利用溶胶－凝胶工艺成功地制备出了ＰＴ／ＳｉＯ２精细复合材料，通过ＸＲＯ，介电频谱和Ｒａｍａｎ光谱对复合样品的结构和性能进行了分析，最后用四波混频方法对的非线性光学性能进行了测量。     

水热法合成氧化镍-二氧化硅催化剂及其用于碳纳米管的制备

以硝酸镍和正硅酸乙酯为原料，制得Ni(OH)2／SiO2二元胶体，经水热晶化法和常压干燥法分别合成了纳米级氧化镍-二氧化硅复合粉体催化剂}用这两种催化剂在相同催化裂解条件下分别制得了多壁碳纳米管；采用XRD和TEM等测试手段对两种催化剂物相、形貌及由两种催化剂制得的碳纳米管形态、收率及纯度作了比较，结果表明：水热晶化法比常压干燥法合成的催化剂粉体颗粒粒径小(为10～20nm），分散性好，催化活性高，使得所制得的碳纳米管管径小(为10～16nm)、分布窄、纯度和收率都相对较高；同时对用不同水热反应温度合成的催化剂(物相不同)制备碳纳米管进行了研究。     

Investigation of cation (Sn2+) and anion (N3-) substitution in favor of visible light photocatalytic activity in the layered perovskite K2La2Ti3O10

Noticeable lowering of the energy gaps have been achieved for the layered perovskite K(2)La(2)Ti(3)O(10) as a result of the attempts made to incorporate Sn(2+) and N(3-) ions. Incorporation of Sn(2+) ions was carried out by the ion-exchange reaction of K(2)La(2)Ti(3)O(10) with aqueous tin(II) chloride solution. Nitrogen incorporation was attempted by the solid state reaction of the parent oxide with urea around 400 °C in air. The resultant oxides have been characterized by power X-ray diffraction, UV-visible diffuse reflectance spectroscopy, and Fourier transform infrared spectroscopy. Room temperature ion-exchange was sufficient to introduce Sn(2+) ions with the resulting product of composition (Sn(0.45)K(0.2)H(0.9))La(2)Ti(3)O(10) · H(2)O. Visible light absorption was observed with the absorption edge red shift of ～ 100 nm from that of the parent K(2)La(2)Ti(3)O(10). The lowering of the band gap was as expected by the contribution of Sn 5s orbitals to the O 2p orbitals in the formation of the valence band. Nitridation using urea resulted not only in nitrogen doping but with the additional sensitization by the presence of carbon nitride (CN) polymers, which again resulted in visible light absorption. The product oxides obtained as a result of cation and anion intended substitutional studies have been found to be useful for the visible light photocatalytic decomposition of organic dyes such as rhodamine B.     

Semiconductor-mediated photocatalysed degradation of two selected azo dye derivatives, amaranth and bismarck brown in aqueous suspension

Semiconductor-mediated photocatalysed degradation of two selected azo dye derivatives such as amaranth (1) and bismarck brown (2) has been investigated in aqueous suspension by monitoring the change in substrate concentration employing UV spectroscopic analysis technique as a function of irradiation time. The degradation was studied under different conditions such as types of TiO(2), pH, substrate concentration, catalyst concentration, and in the presence of electron acceptors such as hydrogen peroxide (H(2)O(2)), potassium bromate (KBrO(3)) and ammonium persulphate (NH(4))(2)S(2)O(8) besides air. The degradation rates were found to be strongly influenced by all the above parameters. The photocatalyst Degussa P25 showed comparatively highest photocatalytic activity. The dye derivative, bismarck brown (2) was found to degrade faster than amaranth dye (1).     

Oxidative decomposition of azo dye C.I. Acid Orange 7 (AO7) under microwave electrodeless lamp irradiation in the presence of H2O2

A novel microwave electrodeless lamp (MWL) rather than traditional electrode lamp (TEL) was used in a H(2)O(2)/MWL system as light source. This technique provided a new way to study the simultaneous effect of both UV-vis light and microwave irradiations. This study showed that H(2)O(2)/MWL process was 32% more effective than H(2)O(2)/TEL process in degrading azo dye Acid Orange 7 (AO7). Further study found that the degradation of AO7 by the H(2)O(2)/MWL process was initiated by the attack of HO* radicals generated by the photolysis of H(2)O(2). However, the direct photolysis of AO7 by MWL irradiation was not negligible. Effect of operation parameters, such as the initial concentrations of AO7 and H(2)O(2) and pH, were investigated. A kinetic model of degradation of AO7 by H(2)O(2)/MWL process was found, in which not only the HO* oxidation but also direct photolysis were considered. The kinetic model was consistent with the experiment results. The degradation of AO7 by H(2)O(2)/MWL corresponded to a pseudo-first order reaction. The apparent reaction constant (k(ap)) was a function of initial concentrations of H(2)O(2) and AO7 and pH of the solution.