高温热解法大规模制备碗状和笼状微球的探索及其机理研究
发布时间：2018-08-31 13:26
【摘要】：由于亚微米尺寸的胶体微粒具有独特的结构与性能,近年来其作为一种新型功能材料受到研究者们越来越多的关注。碗状和笼状微球均为典型的非球形胶体微粒。碗状微球由于具有独特开口形状、不对称结构、中空腔体及单侧平面而被广泛应用于催化、药物缓释、分子印刷、光学、可控释放,超级电容器等方面。而笼状微球由于具有贯穿内外的孔结构及内部空腔的特点而广泛应用于药物贮存与缓释、催化剂载体、微反应容器、吸附等领域。目前制备碗状及笼状微球的方法很多,但依然存在所制备微粒尺寸不均、孔道调控困难以及难以大量制备等问题。本文运用高温热解法,可简单高效地大量制备碗状微球和笼状碳微球。这对于拓展碗状及笼状微球的制备方法及应用等方面具有重要的意义。第二章中,我们通过在空气气氛中高温热解软核硬壳的聚苯乙烯(PS)微球,制备了碗口一致朝上的规整排列的正六边形碗状微球,并探究了煅烧条件及交联度对碗状微球形貌的影响。研究发现,通过大范围调节煅烧温度,可以得到正六边形实心和正六边形碗状两种微球。在270℃~420℃煅烧时,得到的微球均为碗状,而且随温度的升高,碗状微球的壁厚减小,其开口尺寸则先增大后减小;随煅烧时间的增加,碗状微球的壁厚减小,开口尺寸也呈现与升高温度相同的规律;随升温速率的增大,其壁厚呈现逐渐增大的趋势,而其开口尺寸则有一直减小的趋势。随着交联度的增大,碗状微球的壁厚和开口尺寸都增大。但是本章所制备的规整排列的碗状微球由于粘连严重,无法形成可分散的微球。我们通过利用在PS微球表面包覆一层二氧化硅的方法,很好的解决了此问题。表面或内部带有孔结构的碗状微球,由于兼具独特的碗状形貌与孔结构特点,大大拓展了碗状微球的应用,因此关于具有孔结构的碗状微球是近年来的研究热点之一。在第三章中,我们受到第二章制备可分散碗状微球的启发,通过高温热解树莓状PS-Si O2微球,使其线性内核分解并使二氧化硅嵌入到熔胀的交联聚苯乙烯壳层中,制备了表面具有凹坑/孔的可分散碗状微球,并着重研究了煅烧条件对可分散碗状微球形貌的影响。研究发现,随着煅烧温度的增加,碗状微球的形貌由双层碗状向“单层”碗状转变,其表面孔/凹坑深度的大小也随之增加;随着煅烧时间的增加,可分散碗状微球由碗状与多面体微球共存全部转变为为碗状微球,且碗状微球的壁厚和孔数量增加;随着升温速率的增加,碗状微球的形貌由单层碗状到双层碗状再到蘑菇头状与多面体微球共存转变,其表面形貌由大孔到少部分凹坑再到无凹坑过渡。在第四章中,我们利用氮气气氛中高温碳化树莓状PS-Si O2微球制备了笼状碳球。在制备过程中,我们对树莓状微球的制备方法和碳化条件进行了探索,研究发现,通过添加阳离子表面活性剂STAB,可成功制备包覆度较好的树莓状复合微球。并且在碳化条件及碳化模板的选择研究中发现,对20 wt%PS微球进行后交联4h、6h之后,在合适条件下碳化可以得到介孔笼状碳球。通过采用30wt%PS-STAB-Si O2为制备大孔笼状碳球的模板,将其在合适条件下碳化制备了具有大孔的笼状碳球。
[Abstract]:Because of the unique structure and properties of submicron colloidal particles, they have attracted more and more attention as a new functional material in recent years. Both bowl-shaped and cage-shaped microspheres are typical non-spherical colloidal particles. Cage microspheres are widely used in the fields of catalysis, drug release, molecular printing, optics, controlled release, supercapacitor and so on. Cage microspheres are widely used in the fields of drug storage and release, catalyst support, micro-reaction vessel, adsorption and so on because of their pore structure and inner cavity. In this paper, bowl-like microspheres and cage-like carbon microspheres can be prepared simply and efficiently by pyrolysis at high temperature. It is of great significance to expand the preparation methods and applications of bowl-like and cage-like microspheres. Orthogonal hexagonal bowl-shaped microspheres were prepared by pyrolysis of soft core and hard shell polystyrene (PS) microspheres in air atmosphere. The effects of calcination conditions and crosslinking degree on the morphology of the bowl-shaped microspheres were investigated. The hexagonal bowl-shaped microspheres were both bowl-shaped when calcined at 270 ~420, and the wall thickness of the bowl-shaped microspheres decreased with the increase of temperature, the opening size of the bowl-shaped microspheres increased first and then decreased; with the increase of calcination time, the wall thickness of the bowl-shaped microspheres decreased, and the opening size of the bowl-shaped microspheres showed the same rule as the increase of temperature. With the increase of crosslinking degree, the wall thickness and opening size of the bowl-shaped microspheres increase. However, the bowl-shaped microspheres prepared in this chapter can not form dispersible microspheres because of the serious adhesion. The application of bowl microspheres with porous structure has been greatly expanded due to their unique bowl-like morphology and pore structure. Therefore, the research on bowl microspheres with porous structure is one of the hotspots in recent years. In the second chapter, the dispersible bowl microspheres were prepared by pyrolysis of raspberry-like PS-Si O2 microspheres at high temperature. The linear core decomposition of the microspheres was carried out and the silicon dioxide was embedded into the swelling cross-linked polystyrene shell. The dispersible bowl microspheres with pits/pores on the surface were prepared. The effect of calcination conditions on the morphology of dispersible bowl microspheres was studied. It was found that with the increase of calcination temperature, the shape of the bowl microspheres changed from double-layer bowl to single-layer bowl, and the depth of the surface face/pit increased; with the increase of calcination time, the dispersible bowl microspheres changed from bowl-shaped and polyhedron microspheres to bowl-shaped microspheres, and the wall thickness and thickness of the bowl-shaped microspheres increased. With the increase of heating rate, the morphology of bowl microspheres changed from single-layer bowl to double-layer bowl, then to mushroom-head and polyhedron microspheres, and the surface morphology changed from macropores to a few pits and then to no pits. In the preparation process, we explored the preparation methods and carbonization conditions of raspberry-like microspheres. It was found that by adding cationic surfactant STAB, the raspberry-like composite microspheres with better coating degree could be successfully prepared. In the study of carbonization conditions and carbonization template selection, it was found that the 20 wt% PS microspheres were crosslinked after the carbonization. Mesoporous cage carbon spheres were prepared by carbonization under suitable conditions after 4 h and 6 h. The cage carbon spheres with large pores were prepared by carbonization using 30wt% PS-STAB-Si O2 as template.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB34
本文编号：2215123
[Abstract]:Because of the unique structure and properties of submicron colloidal particles, they have attracted more and more attention as a new functional material in recent years. Both bowl-shaped and cage-shaped microspheres are typical non-spherical colloidal particles. Cage microspheres are widely used in the fields of catalysis, drug release, molecular printing, optics, controlled release, supercapacitor and so on. Cage microspheres are widely used in the fields of drug storage and release, catalyst support, micro-reaction vessel, adsorption and so on because of their pore structure and inner cavity. In this paper, bowl-like microspheres and cage-like carbon microspheres can be prepared simply and efficiently by pyrolysis at high temperature. It is of great significance to expand the preparation methods and applications of bowl-like and cage-like microspheres. Orthogonal hexagonal bowl-shaped microspheres were prepared by pyrolysis of soft core and hard shell polystyrene (PS) microspheres in air atmosphere. The effects of calcination conditions and crosslinking degree on the morphology of the bowl-shaped microspheres were investigated. The hexagonal bowl-shaped microspheres were both bowl-shaped when calcined at 270 ~420, and the wall thickness of the bowl-shaped microspheres decreased with the increase of temperature, the opening size of the bowl-shaped microspheres increased first and then decreased; with the increase of calcination time, the wall thickness of the bowl-shaped microspheres decreased, and the opening size of the bowl-shaped microspheres showed the same rule as the increase of temperature. With the increase of crosslinking degree, the wall thickness and opening size of the bowl-shaped microspheres increase. However, the bowl-shaped microspheres prepared in this chapter can not form dispersible microspheres because of the serious adhesion. The application of bowl microspheres with porous structure has been greatly expanded due to their unique bowl-like morphology and pore structure. Therefore, the research on bowl microspheres with porous structure is one of the hotspots in recent years. In the second chapter, the dispersible bowl microspheres were prepared by pyrolysis of raspberry-like PS-Si O2 microspheres at high temperature. The linear core decomposition of the microspheres was carried out and the silicon dioxide was embedded into the swelling cross-linked polystyrene shell. The dispersible bowl microspheres with pits/pores on the surface were prepared. The effect of calcination conditions on the morphology of dispersible bowl microspheres was studied. It was found that with the increase of calcination temperature, the shape of the bowl microspheres changed from double-layer bowl to single-layer bowl, and the depth of the surface face/pit increased; with the increase of calcination time, the dispersible bowl microspheres changed from bowl-shaped and polyhedron microspheres to bowl-shaped microspheres, and the wall thickness and thickness of the bowl-shaped microspheres increased. With the increase of heating rate, the morphology of bowl microspheres changed from single-layer bowl to double-layer bowl, then to mushroom-head and polyhedron microspheres, and the surface morphology changed from macropores to a few pits and then to no pits. In the preparation process, we explored the preparation methods and carbonization conditions of raspberry-like microspheres. It was found that by adding cationic surfactant STAB, the raspberry-like composite microspheres with better coating degree could be successfully prepared. In the study of carbonization conditions and carbonization template selection, it was found that the 20 wt% PS microspheres were crosslinked after the carbonization. Mesoporous cage carbon spheres were prepared by carbonization under suitable conditions after 4 h and 6 h. The cage carbon spheres with large pores were prepared by carbonization using 30wt% PS-STAB-Si O2 as template.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB34
【参考文献】
相关期刊论文 前2条
1 郭阳光;杨穆;吴强;;碗形胶体颗粒/阵列薄膜的制备及性能研究进展[J];化学学报;2013年05期
2 杨晓玲,姚珂,朱以华;纳米结构的空腔二氧化硅微球的制备与缓释行为[J];无机材料学报;2005年06期
，本文编号：2215123
本文链接：https://www.wllwen.com/kejilunwen/cailiaohuaxuelunwen/2215123.html
