| The main objective of this work is the comparison of the grafting polycaprolactone (PCL) on the surface of carboxylate celluloses in H or Na form via ring-opening polymerization (ROP) in order to enhance the compatibility between the cellulose and the hydrophobic polymer matrix. In this work, cellulose was oxidized with catalysts of 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO), sodium hypochlorite and sodium bromide in water. The primary hydroxyl groups were selectively oxidized into carboxyl groups. TEMPO-oxidized cellulose with sodium carboxylate groups(TOC-COONa) was completely converted to individual TEMPO-oxidized cellulose with free carboxyl groups (TOC-COOH) and dispersed in water. The two carboxylate celluloses (TOC-COONa and TOC-COOH) were dewatered and grafted with PCL by ROP. The PCL-grafted cellulosic materials were characterized by Fourier transform infrared (FT-IR), X-ray diffraction, elemental analysis, X-ray photoelectron spectroscopy (XPS), contact angle measurement, Carbon-13 nuclear magnetic resonance spectroscopy (13C-NMR) spectroscopic techniques and thermogravimetric (TG) analyses, respectively. The results indicated that TEMPO-oxidized cellulose with free carboxyl groups (TOC-COOH) was more likely to be modified by PCL, and its corresponding PCL-grafted cellulosic materials was more hydrophobic and thermal stable than that of TEMPO-oxidized cellulose with sodium carboxylate groups (TOC-COONa). |
