期刊
CELLULOSE
卷 22, 期 2, 页码 1063-1074出版社
SPRINGER
DOI: 10.1007/s10570-014-0510-1
关键词
Solid-state cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance (CP/MAS C-13-NMR); Surface grafting; Ring-opening polymerization; Degree of substitution; Cotton linters; Cellulose
资金
- Wallenberg Wood Science Center (WWSC)
- Swedish Research Council (VR)
- Swedish Research Council Formas
In this study, surface-initiated ring-opening polymerization has been employed for the grafting of epsilon-caprolactone from cellulose nanoparticles, made by partial hydrolysis of cellulose cotton linters. A sacrificial initiator was employed during the grafting reactions, to form free polymer in parallel to the grafting reaction. The degree of polymerization of the polymer grafts, and of the free polymer, was varied by varying the reaction time. The aim of this study was to estimate the cellulose nanoparticle degree of surface substitution at different reaction times. This was accomplished by combining measurement results from spectroscopy and chromatography. The prepared cellulose nanoparticles were shown to have 3.1 (+/- 0.3) % of the total anhydroglucose unit content present at the cellulose nanoparticle surfaces. This effectively limits the amount of cellulose that can be targeted by the SI-ROP reactions. For a certain SI-ROP reaction time, it was assumed that the resulting degree of polymerization (DP) of the grafts and the DP of the free polymer were equal. Based on this assumption it was shown that the cellulose nanoparticle surface degree of substitution remained approximately constant (3-7 %) and seemingly independent of SI-ROP reaction time. We believe this work to be an important step towards a deeper understanding of the processes and properties controlling SI-ROP reactions occurring at cellulose surfaces.
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