负载型纳米Pd-M(Ag,Cu)催化剂的制备与催化性能

以自制的聚N,N-二乙基丙烯酰胺接枝聚丙烯腈/聚苯乙烯(PDEAm-g-PAN/PSt)微球作为载体,采用原位还原方法,将与酰胺基团配位的金属离子还原成纳米金属颗粒,制得负载型纳米Pd-M(Ag,Cu)催化剂。采用扫描电子显微镜(SEM)对聚合物微球进行表征,采用透射电子显微镜(TEM)、X射线衍射(XRD)、能谱分析(EDS)和热重分析(TGA)对负载型催化剂进行表征,结果表明:该聚合物微球表面呈现规整的花状形态,Pd-M颗粒均匀分散于PDEAm-g-PAN/PSt微球表面,其粒径约为10nm。将制备的Pd-M(Ag,Cu)催化剂应用于1-辛烯的催化加氢反应,并与商业化催化剂Pd/C相比,催化1-辛烯加氢的效率为Pd-Cu>Pd-Ag>Pd/C。     

负载型纳米Pt颗粒的制备及催化性能研究EI北大核心

通过分散共聚制备了聚N-异丙基丙烯酰胺接枝聚丙烯腈/聚苯乙烯(PNIPAAm-g-PAN/PSt)聚合物微球,以氯铂酸(H2PtCl6)为金属源,乙醇为还原剂,将与酰胺基团配位的铂离子(Pt4+)还原成纳米铂(Pt)颗粒,负载在表面具有特殊形态的聚合物微球表面,制得了分散稳定的负载型纳米Pt颗粒,可用于催化苯胺的聚合等,通过改变反应温度可控制苯胺的聚合速率。     

负载型纳米Pt颗粒的制备及催化性能研究

通过分散共聚制备了聚N-异丙基丙烯酰胺接枝聚丙烯腈/聚苯乙烯(PNlPAAm-gPAN/PSt)聚合物微球,以氯铂酸(H2PtCl6)为金属源,乙醇为还原剂,将与酰胺基团配位的铂离子(Pt4 )还原成纳米铂(Pt)颗粒,负载在表面具有特殊形态的聚合物微球表面,制得了分散稳定的负载型纳米Pt颗粒,可用于催化苯胺的聚合等,通过改变反应温度可控制苯胺的聚合速率.     

不同粒径分布的纳米二氧化钛在醋酸纤维素超滤膜中的分散性能研究

在醋酸纤维素(CA)基料中添加不同浓度经表面改性的不同粒径的纳米二氧化钛(TiO_2)粒子,其中包括平均粒径10、40nm以及这两种粒子的质量比2∶1的级配混合粒子,利用相分离法制备了无机-有机纳米复合CA超滤膜,通过测定膜的孔隙率、孔径分布、渗透性能以及膜表面的电镜扫描(SEM)表征进而研究不同粒径分布对纳米粒子在铸模液中分散性能.结果表明:在不引起纳米粒子团聚的前提下,在CA中添加的纳米粒子粒径越小,复合膜的性能越好;而级配粒子的添加量高于单一粒径粒子的添加量.当膜的渗透性能达到最佳值时,上述3种不同粒径分布的粒子添加量分别为4%、3%、5%(质量分数),而成膜后孔隙率均可达到70%以上,纯水的透水量可分别达到527、443、591L/(m~2·h).这说明颗粒级配分布促进了纳米粒子在铸模液中的分散性能.由于两种粒子混合均匀后存在粒径带双峰分布颗粒级配,在剪切条件下,纳米粒子不易因粒子表面作用引起团结,而团聚在一起的级配颗粒却容易受剪切剥离分散,从而起到促进纳米粒子在聚合物溶液中的分散作用.     

Pd-Ag合金纳米粒子合成及其催化性能研究

采用W/O微乳液法合成Pd-Ag合金纳米粒子并结合微乳浸渍工艺制备了负载型Pd-Ag/Al_2O_3催化剂。利用紫外-可见分光光度计和透射电子显微镜对合成的Pd-Ag合金纳米粒子进行表征,并考察了对乙炔加氢反应的催化性能。结果表明,在聚氧乙烯(4)月桂醚(Brij30)/正辛烷/水微乳液体系中加入聚乙烯基吡咯烷酮(PVP),对生成的纳米粒子起到二次保护作用,Pd与Ag以合金纳米粒子形式稳定存在且粒径大小均一,粒径在1～2nm,可随PVP以薄膜形态负载并分散在Al_2O_3表面。当PVP相对分子质量为8000～10000,cPVP8:c(Pd+Ag)=0.1时,合成的Pd-Ag合金纳米粒子数量最多,粒径最小,制备的Pd-Ag/Al_2O_3催化剂具有良好的乙炔加氢活性和选择性。     

钯纳米颗粒在不同碳质材料上的自发沉积与电活性

在无还原剂存在下,氯化钯在Vulcan XC-72碳粉(C)、多壁碳纳米管(MWCNT)和碳球(CM)等碳质材料表面上自发还原为金属钯,从而得到相应的钯纳米颗粒(Pd-C、Pd-MWCNT和Pd-CM)。用阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)对这些碳质材料修饰后,采用同样的自发还原方法分别制备出Pd/CTAB-C、Pd/CTAB-MWCNT和Pd/CTAB-CM催化剂。结果表明,CTAB修饰后的MWCNT明显增加了钯纳米颗粒的自发沉积量,粒径大约为9 nm,而在MWCNT上沉积的纳米Pd粒径为19 nm。Pd/CTAB-MWCNT在碱性条件下对乙醇氧化的电流密度达到44.2 m A·cm-2,与其他碳载体负载的Pd纳米催化剂相比,对乙醇氧化具有强而稳定的电催化活性。     

超声诱导CTAB/SDS溶液中纳米Pd粒子的形貌控制及对甲醛的电催化氧化

在十六烷基三甲基溴化铵(CTAB)-十二烷基硫酸钠(SDS)混合乙醇水溶液中,超声辐射PdCl2,合成了纳米Pd粒子,用XRD、TEM、选区电子衍射(SAED)、HRTEM和低温氮吸附-脱附等技术进行了表征,考察了CTAB/SDS组成对纳米粒子形貌的影响,纳米Pd粒子修饰玻碳电极对甲醛的电催化活性也通过循环伏安法进行了研究。结果表明:通过改变CTAB/SDS组成可以调控纳米Pd粒子的粒径和形貌;当CTAB与SDS物质的量之比为1∶1、超声反应60min时,得到呈多边形的纳米Pd粒子,粒径范围在10～20nm之间,比未添加表面活性剂样品的比表面积增大了14m2.g-1,对甲醛有较高的电催化活性。     

双亲性纳米TiO2复合粒子的制备与研究

采用疏水型硅烷偶联剂KH570表面接枝改性纳米TiO2,引入化学键结合的不饱和双键,再通过无皂乳液聚合法合成双亲性聚丙烯酸(PAA)-g-硅烷偶联剂KH570-g-纳米TiO2复合粒子.研究了偶联剂用量对纳米TiO2粒子分散性以及聚合条件对聚合物接枝率变化和微观形态的影响.红外光谱和热重测试分析结果表明,纳米TiO2表面偶联剂接枝率为7.62％,聚合物接枝率达61.3％;透射电镜观察表明,偶联剂处理使纳米TiO2的亲油性和分散性均提高,聚合物接枝后的复合粒子能够在有机溶剂中分散均匀且粒径增加至30nm左右.     

碳纳米管负载铂金颗粒的微观形貌表征

以碳纳米管负载粒径小于10 nm的铂金纳米颗粒为研究对象,采用热场发射扫描电镜表征其微观形貌,探讨不同的探测器和加速电压对样品成像效果的影响。结果表明,对于同一种探测器,低加速电压测试条件下可获得比较清晰的样品表面细节;在加速电压为1 kV时,使用SE2和InLens探测器无法观测到碳纳米管表面负载的铂金纳米颗粒,而使用ESB探测器可以清晰观察到粒径为3～10 nm的铂金颗粒在碳纳米管上的分布情况。     

功能化碳纳米管负载钯纳米催化剂提高苯甲醇选择性氧化

对多壁碳纳米管进行纯化和功能化处理,比较了未氧化处理与经浓硝酸和浓硫酸混酸(浓硫酸与浓硝酸体积比为3∶1)处理后的不同多壁碳纳米管(MWCNTs)为载体的Pd催化剂(Pd/MWCNTs)的分散性和粒径。利用X线粉末衍射仪(XRD)、透射电镜(TEM)、X射线能谱(EDS)和傅里叶变换红外光谱仪(FT-IR)等测试手段对所得的样品进行了表征。结果表明,MWCNTs表面不修饰不利于金属Pd纳米粒子的沉积,混酸处理使MWCNTs表面有大量的含氧活性基团,能够促进负载的Pd纳米粒子均一分布,明显提高了苯甲醇氧化为苯甲醛的选择性和转化率。     

Ni/PSt/TiO2多层芯-壳结构电磁响应

制得了粒径均匀、兼有电磁响应的镍／聚苯乙烯／二氧化钛(Ni／PSt／TiO2)三层核-壳结构的复合微球．用红外光谱、X射线衍射及透射电镜对微球进行了表征，研究了包覆前后微粒的沉降性、导电性、耐蚀性、热稳定性以及在电、磁场作用下的运动．结果表明，所制得的镍／聚苯乙烯／二氧化钛(Ni／PSt／TiO2)复合微球对电磁场有良好的响应性，在相互垂直的电场与磁场作用下排列形成了一种网状花样结构，为利用电、磁场调控排列粒子成三维有序结构提供基础．     

Ni/PSt/TiO2多层芯-壳结构电磁响应

制得了粒径均匀、兼有电磁响应的镍/聚苯乙烯/二氧化钛(Ni/PSt/TiO₂)三层核-壳结构的复合微球。用红外光谱、X射线衍射及透射电镜对微球进行了表征,研究了包覆前后微粒的沉降性、导电性、耐蚀性、热稳定性以及在电、磁场作用下的运动。结果表明,所制得的镍/聚苯乙烯/二氧化钛(Ni/PSt/TiO₂)复合微球对电磁场有良好的响应性,在相互垂直的电场与磁场作用下排列形成了一种网状花样结构,为利用电、磁场调控排列粒子成三维有序结构提供基础。     

Interpenetrating polymer networks of poly(N-vinylacetamide) and stimuli responsive polymers applied to novel amphiphilic gel

The swelling behaviors of IPN with poly(N-vinylacetamide) (PNVA), which possibly converts from nonionic gel to cationic gel, and the stimuli responsive polymers, such as poly(acrylic acid) (PAAc) and poly(N-isopropylacrylamide) (PNIPAm) were investigated in order to prepare the stimuli responsive amphiphilic gel. When the monomer concentrations were uniformed at the IPN preparation, the obtained PNVA/PAAc IPN showed the pH responsivity with around 100 of swelling ratio at pH 4 to around 1 of swelling ratio at pH 2, although it lost the amphiphilicity due to the lack of swelling in ethanol. On the other hand, the gelation of N-vinylacetamide at 2 M in PNIPAM gel resulted in thermosensitive and amphiphilic hydrogel, that the swelling ratio in EtOH/water (3/7, v/v) also decreased, compared to the value in water at 25 degrees C.     

Novel one-step route for synthesizing sub-micrometer PSt hollow spheres via redox interfacial-initiated method in inversed emulsion

Interfacial-initiated polymerization of styrene (St) was carried out in inversed emulsion with cumene hydroperoxide (CHPO) and ferrous sulfate (FeSO₄)/disodium ethylenediaminetetraacetate (NaEDTA)/sodium formaldehyde sulfoxylate (SFS) as the redox initiation system. The water-soluble Fe²⁺-NaEDTA-SFS acted as the reducing component and the oil-soluble CHPO as the oxidant component of the redox initiation system. Therefore, the primary radicals were produced mainly at the oil/water interface to initiate the polymerization of St. Thus, sub-micrometer hollow polystyrene (PSt) spheres were obtained by one-stage polymerization, which was supported by the techniques of transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM).     

磷掺杂中空碳球的制备及其电容性能EI北大核心CSCD

以酚醛预聚体和苯乙烯为原料通过水热法一步合成中空聚合物球(HPS),再以三氯化磷为反应剂通过傅-克反应对HPS处理得到含磷交联聚合物,经高温炭化和KOH活化制备磷掺杂中空碳球(AP-HCS)。采用FT-IR,TG,SEM,TEM,Raman,BET,XPS等手段对含磷聚合物和碳材料的组成、结构与形貌进行表征,测试碳材料在1 mol/L H2SO4介质中的电容性能。结果表明:AP-HCS的比表面积可达2177 m2/g,在1 A/g电流密度下,比电容为288 F/g,5 A/g电流密度下经循环充放电5000次后比电容值仍能保持88.9%,具备良好的电容性能。     

A dual template method for synthesizing hollow silica spheres with mesoporous shells

PS/silica core/shell composites were synthesized by the modified Stöber method using polystyrene spheres and cetyltrimethylammonium bromide as dual templates under room temperature. The silicate species and the templates were self-assembled to form mesoporous silica shell on the surface of the PS spheres. Hollow silica spheres with mesoporous shell were obtained by removing the polymer core and the templates through calcination. The hollow silica spheres showed high specific surface area of 1099.5 m²/g and narrow pore size distribution centered at 2.31 nm.     

Tailoring Polymer Colloids Derived Porous Carbon Spheres Based on Specific Chemical Reactions

Porous carbon spheres derived from polymer colloids with regular geometry, monodispersed morphology, well-controlled contents and structures play important roles in many areas of application, such as energy storage/conversion, gas adsorption/separation, catalysis, and chemo-photothermal therapy. Suitable polymerization reaction and synthetic strategy are both critical for the obtainment of stable polymer colloids as carbon precursors. Basic polymerization reactions are the cornerstones of synthetic strategies, which directly provides the direct molecular-based design of functionalized polymer/carbon spheres. Thus, this progress report mainly focuses on the summary of suitable polymerization reactions for colloidal polymer derived porous carbon spheres. Recent advances in the synthetic strategies and applications are also discussed, including their corresponding polymerization reactions. Finally, the perspectives for the development of polymer derived porous carbon spheres are provided based on the controlled synthesis of polymer colloids and optimization over the carbonization process to achieve highly functionalized carbon spheres for practical applications.     

C<Subscript>60</Subscript> end-functionalized four-armed polymers: synthesis and optical limiting properties

A series of bromo-terminated four-armed homopolymers [polystyrene (PSt) and poly(methyl methacrylate) (PMMA)], prepared by atom transfer radical polymerization (ATRP), were subsequently functionalized with fullerene C₆₀ by atom transfer radical addition (ATRA) reaction using CuBr/2,2′-bipyridine (bipy) as the catalyst system. The C₆₀ end-capped four-armed polymer derivatives were then characterized by gel permeation chromatography (GPC), UV–vis, FT-IR, thermal gravimetric analyses (TGA) and differential scanning calorimeter (DSC). Another technique of synthesizing C₆₀-functionalized four-armed polymers from azide functional polymers was also applied for comparison. The optical limiting behavior of C₆₀ end-capped four-armed polymers prepared via ATRA reaction were measured in THF solution at 532 nm. Both groups of fullerene-functionalized polymers (C₆₀-PSts and C₆₀-PMMAs) are provided with optical limiting properties.     

核壳高分子微球的制备

介绍了核壳高分子微还需的制备方法及影响因素，并制备出了核壳型聚苯乙烯/聚甲基丙烯酸甲酯微球，同时进行了表征。     

Effect of compatibility between europium complexes and styrene monomer on preparation of europium-encapsulated microspheres by dispersion polymerization

Two europium organic complexes of Eu(DBM)₃Phen (DBM = dibenzoylmethane, Phen = 1,10-phenanthroline) and Eu(TTA)₃·2H₂O (TTA = 2-thenoyltrifluoroacetone) with different structures are successfully encapsulated into polystyrene (PSt) microspheres by in situ dispersion polymerization. These fluorescent microspheres are monodisperse and spherical in shape with the homogeneous distribution of europium complexes in the polymer matrix, as investigated by field emission scanning electron microscopy and confocal laser scanning microscopy. The europium content in the microspheres is measured by inductively coupled plasma atomic emission spectrometer. It is shown that the compatibility of the europium complex with the styrene monomer has a great impact upon the europium content in the PSt microspheres by dispersion polymerization. As the complex amount increases, the europium content in the microspheres containing Eu(DBM)₃Phen increases, while that in the microspheres containing Eu(TTA)₃·2H₂O first increases and then reaches a saturated value at a high addition amount. Fluorescence properties indicate that the PSt polymer is a valuable matrix for improving the emission intensity of Eu(DBM)₃Phen yet not an ideal matrix for Eu(TTA)₃·2H₂O, which is demonstrated by the measurement of fluorescence lifetime.