H型和Na型羧基纤维素表面改性接枝己内酯的比较研究

The Comparison of Grafting Polycaprolactone on Carboxylate Celluloses in H or Na Form

利用TEMPO/Na Br/Na Cl O反应体系将纤维素表面的C6-伯羟基氧化成羧基,获得羧基纤维素;以羧基纤维素为原料、己内酯为接枝共聚改性剂,通过开环聚合,合成了表面接枝聚己内酯的纤维素产物。讨论了H型和Na型羧基纤维素接枝己内酯的情况;红外光谱、核磁共振、X射线衍射、表面光电子能谱、表面接触角、热重等分析表明,H型羧基纤维素接枝己内酯的接枝率高于Na型羧基纤维素,且其接枝产物的疏水性更好、热稳定性更高。

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）.