Abstract
Model hemicellulose-cellulose composites, that mimic plant cell wall polymer interactions were prepared by synthesizing deuterated bacterial cellulose with glucomannan or xyloglucan. Dilute acid pretreatment (DAP) of these materials was studied using small angle neutron scattering, X-ray diffraction and sum frequency generation spectroscopy. The pretreated cellulose macrofibril dimensions were smaller and they formed a less entangled macrofibrillar network compared to native cellulose. In addition, the crystallite size dimension along the (010) plane increased. Glucomannan-cellulose underwent similar changes to cellulose, except that the macrofibrillar network was more entangled after DAP. On the other hand, in xyloglucan-cellulose the macrofibril dimensions and macrofibrillar network were relatively unchanged after pretreatment but the cellulose 1 content was increased. Our results point to a tight interaction of xyloglucan with microfibrils while glucomannan only interacts macrofibril surfaces. This study provides insight into hemicellulose-cellulose interactions and may help in improving pretreatment processes or engineering plants with decreased recalcitrance.