Production of Cone-Shaped Graphitic Whisker in Scrolled Natural Polymer Film as”Microreactor”

摘要

Cone-shaped graphitic whiskers(CGW)are a type of carbon whiskelrs,characterized by a super-helical cone stack of graphene!).CGW are easily produced by carbonization of woody plants2,particularly of silica-rich species,because silica can be converted to SiC via heat treatment at>20G0°C,which works as nuclei for a stable growth of CGWs with their apex angles in the range of 135-140°.However,the growth mechanism has not been elucidated.Our previous study’indicated that wood cells work as”microreactors”affecting the shape and size of the CGWs grown inside.The wood cell is considered to have multiple functions,namely,to pyrolytic gas,accumulate it inside,and simultaneously work as a scaffold for the SiC nuclei.Anatomically different species of woody and herbal plant cells imply that differences in the size,permeability of gas,and Si deposition affected the features of the resultant CGWs2).To elucidate the growth mechanism,we need to prepare for man-made”microreactors”wherein the cavity size can be controlled.A type of”intelligent”polymer films has been invented,which self-scroll responding to circumstances because of their expansion-gradient in the thickness direction3).By designing the thickness and gradient of the film,the curvature of scrolling can be controlled.Recently,self-scroll systems have been successfully produced by bio-polymers3'which fairly maintain their original shape under the carbonization process.In this study,we aimed to use this biopolymer scroll as a”microreactor”and synthesize CGWs inside,under controlling.