聚苯胺微/纳米材料的湿化学法合成及其形貌调控

【作者】 周传强；

【导师】 郭荣；

【作者基本信息】 扬州大学 ， 物理化学， 2009， 博士

【摘要】 聚苯胺纳米材料,集功能导电高分子与纳米颗粒的特性于一身,在科学上和技术上已经引起了人们广泛的关注,并成为材料领域新的研究热点。聚苯胺纳米材料的化学制备方法大致包括:固体模板法(也称“硬模板”法),反应性模板法,基于表面活性剂的模板导向法(又称“软模板”法),固体表面生长法,界面聚合法等等。目前有关聚苯胺的研究主要集中在聚苯胺纳米结构的调控上,而有关苯胺的氧化聚合过程与聚苯胺纳米结构形成之间的内在联系在科学界仍没有达成共识。基于上述考虑,本文研究了无任何添加剂的水溶液、酸/碱溶液、表面活性剂稀溶液及胶束溶液、以及水/有机相界面等不同条件下,苯胺的氧化聚合过程与聚苯胺纳米结构生长之间的关联,为聚苯胺纳米材料的可控合成提供理论依据。在无任何添加剂的水溶液中通过苯胺的氧化聚合法制备了聚苯胺多级结构——纳米纤维编织的微米席。以电镜、红外光谱以及XRD等手段测试了不同反应时间所得产物的形貌、化学结构以及结晶性,进而讨论了聚苯胺微米席的生长机理。在较低氧化剂/单体摩尔比条件(0.1:1-0.8:1)下,苯胺稀溶液氧化聚合制备了聚苯胺二维片结构与三维花状多级结构。在该摩尔比为0.1:1-0.3:1时,产物的形貌主要为片状结构;而当该比例在0.4:1-0.8:1之间时,得到了花状结构的产物。分别研究了它们的生长过程,探索了其形成机理。考察了酸/碱性对聚合过程以及产物形貌、结构的影响。在室温、无机酸稀溶液中制备了导电态的聚苯胺矩形亚微米管组装的扇形超级结构。通过管基扇状结构生长过程的测量以及苯胺氧化聚合过程的讨论,推测了矩形管的形成及其扇形组装的机理。在碱性溶液中,苯胺氧化聚合得到了纳米片基的微米球、纳米棒基的微米球、纳米盘基的微米棒。进一步实验发现,微米棒是由纳米盘通过交联反应面对面叠加而成,称之为纳米盘基的微米塔。考察了不同反应时间微米塔的形貌进化与化学结构变化,进而探讨了其生长过程。在阴离子表面活性剂稀溶液中制备了聚苯胺矩形亚微米管。考察了苯胺单体浓度、氧化剂/单体摩尔比对矩形管尺寸与形貌的影响,并研究了其生长过程。当该体系中添加有无机酸时,即在SDS/HCl稀溶液中制备了表面覆盖有纳米结构的矩形亚微米管。研究了反应温度、SDS与HCl浓度对产物形貌的影响,讨论了该结构的生长机理。在TX-100胶束体系中,通过苯胺、吡咯混合物的氧化聚合,成功地制备了聚(苯胺-吡咯)共聚空心纳米球。DLS实验证实了反应体系中TX-100胶束的存在以及共聚单体在胶束内的增溶;讨论了共聚空心纳米球的形成机理。以FTIR、UV-vis与1H NMR谱图表征了产物的化学结构,从而证实了产物的共聚物组成。提出了一种新的有机/水相界面聚合方法,水相中引入表面活性剂导向界面聚合,在玻璃基体表面制备出了聚苯胺纳米材料。通过几种分子(聚合物链、表面活性剂与醇分子)之间的氢键作用与静电作用,在玻璃表面合成了不同形貌的聚苯胺,如带状结构、花状结构,片状结构,以及纳米带基的花状超结构。讨论了作为有机溶剂的醇链长与链结构、表面活性剂类型对产物形貌的影响,初步探讨了其生长机理。更多还原

【Abstract】 Polyaniline (PANI) nano-materials have caused extensive attentions in the fields of science and technology, and been a new hotspot of material researches, because they possess the excellences of both conducting polymers and nanomaterials. The chemical synthesis to PANI nanomaterials mainly includes the solid template approach (hard template), the reactive template route, the surfactant-based template-guided polymerization (soft template), the surface growth on the solid, the interfacial polymerization and so on. To date, these researches about PANI focus mainly on the synthesis of PANI nanomaterials, however, there still are not general cognitions in this field about the intrinsic relations between the polymerization courses of aniline and the formations of PANI nanostructures. Herein, we investigate the relationships between the oxidation polymerization of aniline and the growth of PANI nanostructures under the different reaction conditions, such as the aqueous solution without any additive, the acidic or alkaline solutions, the diluted and micellar solutions of surfactant and the interfacial polymerization system, providing the theories to the controlled fabrication of PANI nanostructures.Micromats of PANI nanofibers as a novel hierarchical structure are prepared in water without the aid of any additive. The growth processes of PANI micromats are followed through montoring the different stage of polymerization, based on which a possible formation mechanism is proposed through discussing the polymerization courses. Subsequently, PANI plate-like structures and flower-like hierarchical superstructures are successfully fabricated by the oxidation of aniline with the oxidant/monomer molar ratio varying between 0.1:1 and 0.8:1. With the oxidant/monomer molar ratio between 0.1:1-0.3:1, the plate-like structures can be produced, while the flower-like architectures are obtained at the molar ratio of 0.4:1-0.8:1 by the oxidative polymerization.A low-concentration inorganic-acid solution approach is proposed to fabricate conducting PANI fanlike architectures of rectangular sub-microtubes. Through measuring the growth processes of tube-based fanlike PANI and discussing the oxidation polymerization of aniline, we give the possible interpretations to the formation of PANI rectangular tubes and their fanlike assembly, respectively. When the reaction medium is altered to alkaline solution, nanosheet- or nanorod-based microspheres and nanorod-based microrods of PANI have been successfully fabricated. With the increasing temperature of polymerization, the building blocks of PANI microspheres change from nanosheets to nanorods, accompanied by the appearance of tower-like structures based on nanoplates. The time-dependence morphological evolvement of tower-like hierarchical structures is examined, based on which we discuss their growth courses.PANI rectangular sub-microtubes are successfully produced through the oxidation polymerization of aniline in dilute anionic surfactant (sodium dodecyl sulfate, SDS) solution. The shape (rectangle or square) of cross sections and the uniformity of PANI sub-microtubes can be appropriately adjusted by simply tuning the concentration of aniline monomer and the molar ratio of APS to aniline, respectively. When low-concentration HCl is added into above system, nanostructure-covered rectangular sub-microtubes of PANI can been synthesized by the polymerization of aniline. The influences of temperature and the concentrations of SDS and HCl on the morphology of product are studied in detail, in order to explore the growth mechanism. In the Triton X-100 (TX-100) micellar solution, the poly(aniline-co-pyrrole) (PACP) hollow nanospheres are successfully prepared via the oxidation polymerization of the mixture of aniline and pyrrole. The spherical micelles consisted of TX-100 and co-monomers in the reaction system and the polymerization processes are monitored by dynamic laser-light scattering (DLS) technology. Based on our experiment results, a possible mechanism to PACP hollow nanospheres is speculated to explain the formation. Additionally, FTIR, UV-visible, 1H NMR spectra provide sufficient data to characterize the copolymer chemical structure of PACP.A novel synthesis approach has been developed to fabricate PANI nanomaterials on the glass surface through the aqueous/alcohol interfacial polymerization. Different from the usual interfacial reaction, surfactant is employed as structure-orienting agent to manipulate the propagation and assembly of PANI nanostructures. PANIs with different morphologies, such as belt-like structures, flow-like hierarchical structures, nanosheets, and belt-based marigold-like structures, are tailored with the aid of the hydrogen bonding among polymer, surfactant and alcohol, or the electrostatic interactions between polymer and glass substrate.更多还原