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

中文关键词:  羧基纤维素  聚己内酯  接枝改性  疏水性  热稳定性

Key Words:carboxylate celluloses  polycaprolactone  grafting  hydrophobic  thermal stabilization

中文摘要:

      利用TEMPO/NaBr/NaClO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。

Abstract:

      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).