Silica Nanocasts of Wood Fibers: A Study of Cell-Wall Accessibility and Structure

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• 作者：Per Valdemar Persson ; Jonas Hafré ; n ; Andrew Fogden ; Geoffrey Daniel ; and Tommy Iversen
• 刊名：Biomacromolecules
• 出版年：2004
• 出版时间：May 2004
• 年：2004
• 卷：5
• 期：3
• 页码：1097 - 1101
• 全文大小：207K
• 年卷期：v.5,no.3(May 2004)
• ISSN：1526-4602

文摘

The porosity and the available surface area of a lignocellulosic fiber can influence the accessibility andreactivity in derivatization and modification reactions because the porous cell-wall network determines theupper size limit for molecules that can penetrate and react with the interior of the wall. To obtain informationconcerning the accessibility of the porous cell wall of wood fibers, surfactant-templated sol-gel mineralizationhas been examined. Wood and kraft pulp samples of Norway spruce were impregnated with a silica sol-gel and subsequently heated (calcined) and transformed into structured mesoporous silica. Microscopy studies(environmental scanning electron microscopy, transmission electron microsopy, TEM) on the silica castsshowed that the three-dimensional architecture of the wood and pulp fiber cell wall was revealed down tothe nanometer level. Image analysis of TEM micrographs of silica fragments from the never-dried pulprevealed complete infiltration of the cell-wall voids and microcavities (mean pore width 4.7 ± 2 nm) by thesol-gel and the presence of cellulose fibrils with a width of 3.6 ± 1 nm. Cellulose fibrils of the same widthas that shown by image analysis were also identified by nitrogen adsorption measurements of the pore sizedistribution in the replicas.