Patterning nanoroads and quantum dots on fluorinated graphene

Using ab initio methods we have investigated the fluorination of graphene and find that different stoichiometric phases can be formed without a nucleation barrier, with the complete “2D-Teflon” CF phase being thermodynamically most stable. The fluorinated graphene is an insulator and turns out to be a perfect matrix-host for patterning nanoroads and quantum dots of pristine graphene. The electronic and magnetic properties of the nanoroads can be tuned by varying the edge orientation and width. The energy gaps between the highest occupied and lowest unoccupied molecular orbitals (HOMO-LUMO) of quantum dots are size-dependent and show a confinement typical of Dirac fermions. Furthermore, we study the effect of different basic coverage of F on graphene (with stoichiometries CF and C₄F) on the band gaps, and show the suitability of these materials to host quantum dots of graphene with unique electronic properties.     

Chemical modification of jute fibers for the production of green-composites

Natural fiber reinforced composites is an emerging area in polymer science. Fibers derived from annual plants are considered a potential substitute for non-renewable synthetic fibers like glass and carbon fibers. The hydrophilic nature of natural fibers affects negatively its adhesion to hydrophobic polymeric matrices. To improve the compatibility between both components a surface modification has been proposed. The aim of the study is the chemical modification of jute fibers using a fatty acid derivate (oleoyl chloride) to confer hydrophobicity and resistance to biofibers. This reaction was applied in swelling and non-swelling solvents, pyridine and dichloromethane, respectively. The formation of ester groups, resulting from the reaction of oleoyl chloride with hydroxyl group of cellulose were studied by elemental analysis (EA) and Fourier Transform infrared spectroscopy (FTIR). The characterization methods applied has proved the chemical interaction between the cellulosic material and the coupling agent. The extent of the reactions evaluated by elemental analysis was calculated using two ratios. Finally electron microscopy was applied to evaluate the surface changes of cellulose fibers after modification process.     

含氟硅乳液膜的梯度功能分布和疏水性能

采用核壳乳液聚合的方法制备出具有疏水性能的氟硅丙乳液.探讨了膜疏水性能的影响因素,通过水接触角和多功能光电子能谱仪表征了有机氟在孔液成膜中的梯度分布功能,发现由于甲基丙烯酰氧基丙基三异丙氧基硅烷单体在涂膜固化过程中的马兰各尼效应以及与有机氟的相容性,对有机氟单体向表面迁移有促进作用,使膜疏水性能有较大提高.通过扫描电子显微镜观察到氟硅丙乳液膜表面呈现明显的由"蒲公英"状粒子排列交叉而成的枝状网络结构,与硅丙乳液膜有明显区别.     

木质素磺酸钠聚羧酸减水剂的制备研究

以木质素磺酸钠作为聚羧酸减水剂的合成原料,在水溶液中与聚羧酸减水剂单体进行接枝共聚反应,制得木质素磺酸钠聚羧酸减水剂,并对其制备工艺进行优化,得到最优实验方案为:木质素磺酸钠质量分数为16%,PEG-1000和MA的物质的量比为0.9∶1.0,丙烯酸与马来酸酐物质的量比为2.8∶1.0,聚合时间为3h,酯化时间为4h,最优条件下制得的产品的水泥净浆流动度(掺量为0.2%,水灰质量比为0.29)为241mm。红外测试表明木质素磺酸钠分子结构上成功接上了聚氧乙烯基、酯基、羧酸基及酰胺基等官能团。     

淀粉接枝两性离子絮凝剂的制备

研究了两性单体的合成条件,以及以过硫酸铵为引发剂时,其与淀粉进行接枝共聚的规律。实验结果表明,当pH9～10,反应温度85℃,反应时间为5h时,两性单体收率最高,可达98%以上;当引发剂浓度为2.2mmol／L,单体用量(单体／淀粉)为1.8／1(质量分数),反应温度为48℃,反应时间为4h时,接枝共聚反应的G和GE均较高,且所得产品的特性粘数亦较大。     

交联型醋-丙乳液的合成及性能

以醋酸乙烯酯(VAC)、丙烯酸丁酯(BA)等为主要原料,TAC和HEA为交联单体,采用半连续预乳化种子乳液聚合法合成了醋-丙乳液,讨论了各工艺条件对乳液性能的影响。用激光粒度分布仪、红外光谱仪(FTIR)、静态接触角测试仪等测试手段,对合成产物进行了性能和结构表征。结果表明,单体质量比m(VAC):m(BA)=3:2、乳化剂OP-10和SDS总用量为单体的3.5%、引发剂APS用量为单体的0.6%时,单体转化率可高达98.3%,凝胶率可以控制在0.5%左右;交联单体TAC的用量为单体的1.6%时,聚合物吸水率为8.5%,膜与水的接触角为69.5°。     

S-BPDA/ODA型聚酰亚胺的合成及聚集态结构对薄膜性能的影响

采用两步法和一步法涂膜热酰亚胺化工艺分别制备了S-BPDA/ODA的聚酰亚胺(PI)薄膜。偏光观察发现,一步法制备的薄膜经过250℃以上的温度处理后出现明显的微晶结构,在相同的酰亚胺工艺条件下两步法制备的薄膜没有出现微晶结构。DMA测试表明,一步法与两步法制备的薄膜Tg分别为294℃和276℃;相比两步法,一步法制备的薄膜具有更佳的力学和热稳定性能。分析认为,微晶结构的交联作用和高酰亚胺化程度使一步法制备的薄膜具有更佳的性能。     

EPDM和NX8000K对iPP结构及性能的影响

针对等规聚丙烯(iPP)韧性差,弹性体改性后降低了其结晶温度与结晶能力的问题,采用弹性体三元乙丙橡胶(EPDM)和成核剂山梨醇二缩芳香醛(NX8000K)联合改性iPP;并使用差示扫描量热仪(DSC)、X射线衍射仪(XRD)、偏光显微镜(POM)、扫描电子显微镜(SEM)和万能试验机等手段对iPP/EPDM/NX800...     

芳香族氟化物的合成方法研究进展

人们对环保的要求越来越高,使得绿色化学成为21世纪化学发展的目标与方向。同时,未来精细化学品的发展趋势必须符合高效、安全和经济的原则。从氟原子的特殊性质出发,简述了芳香族氟化物在医药、农药和染料等领域的突出优点及广泛应用前景。详尽介绍了不同的氟化合成方法：直接氟化法、Balz—Schiemann法、无水氟化氢重氮法、电化学氟化法、卤素交换法、氟代脱硝法、超声波和微波法。针对这些方法,讨论了它们的反应原理,具体分析了各自的优缺点,并提出了对今后芳香族氟化物发展的建议。     

活性单体对超支化聚氨酯丙烯酸酯的影响

研究了活性单体种类及用量对超支化聚氨酯丙烯酸酯(HBUA)光固化膜机械性能的影响,并用光差扫描量热法(Photo-DSC)对超支化聚氨酯丙烯酸酯的光聚合反应速率进行了研究.结果表明,己二醇二丙烯酸酯(HDDA)比三羟甲基丙烷三丙烯酸酯(TMPTA)能更好地调节HBUA固化膜的综合性能,并促进UV固化反应的进行.HDDA的适宜质量分数为20%.