Tailoring the Degree of Polymerization of Low Molecular Weight Cellulose
โ Scribed by Marcel Meiland; Tim Liebert; Thomas Heinze
- Publisher
- John Wiley and Sons
- Year
- 2011
- Tongue
- English
- Weight
- 495 KB
- Volume
- 296
- Category
- Article
- ISSN
- 1438-7492
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โฆ Synopsis
Abstract
The degradation of cellulose to lmw samples with $\overline {DP} _{{\rm w}} $ varying from 15 to 130 is investigated. Cellulose samples prepared from the hydrolysis of regenerated cellulose fibers in dilute HCl possess $\overline {DP} _{{\rm w}} $โ=โ50. Applying homogenous degradation of microcrystalline cellulose in H~3~PO~4~ at RT for 3 weeks, samples with $\overline {DP} _{{\rm w}} $โ=โ35 and a PDI of 1.58 are obtained. Decreasing the hydrolysis temperature to 8โยฐC results in lmw cellulose with $\overline {DP} _{{\rm w}} $โ>โ70. Fractionation in DMA/LiCl provides samples with $\overline {DP} _{{\rm w}} $โ=โ12 to 130, together with a narrow molecular weight distribution. Detailed structural analysis by 2D NMR spectroscopy reveals that the prepared lmw celluloses are suitable as mimics for cellulose. magnified image
๐ SIMILAR VOLUMES
Polymerization of styrene to high degrees of conversion (up to 99.8%) was carried out. The obtained polystyrene was fractionated by distribution between two liquid phases and also by fractionating precipitation. Molecular weights of the fractions were determined and the molecular weight distribution