Chemical modification of wood cellulose fibers is important for tailored wood-polymer interfaces, reduced moisture sorption, and novel grades of chemical wood pulp. The present study shows how the reaction solvent system influences hydroxyl accessibility during chemical fiber modification. Surface initiated ring-opening polymerization of ε-caprolactone from wood cellulose fibers was investigated in a wide range of solvent systems. The hydrogen bond donor strength of the solvent increased graft density and the amount of grafted polycaprolactone (PCL) on the fiber surface, and on nanoscale fibrils inside the fiber. Specifically, the reaction system with acetic acid as a new, green solvent for cellulose grafting increased graft density 24 times compared to bulk polymerization conditions. The results show relationships between solvent properties, hydroxyl accessibility, and grafting results in cellulosic plant fibers. The study clarifies the opportunities provided by controlling the interior of the cellulosic plant fiber cell wall during chemical modification so that the fiber becomes a swollen cellulose nanofibril gel.

中文翻译：

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木质纤维素纤维内部的聚合物接枝，通过纤维溶胀改善了羟基的可及性。

木材纤维素纤维的化学改性对于定制的木材-聚合物界面，减少的水分吸收以及新型化学木材浆至关重要。本研究表明了反应溶剂体系如何在化学纤维改性过程中影响羟基的可及性。在多种溶剂体系中研究了木质纤维素纤维表面引发的ε-己内酯的开环聚合反应。溶剂的氢键供体强度增加了纤维表面以及纤维内部纳米级原纤维的接枝密度和接枝聚己内酯（PCL）的数量。具体而言，与本体聚合条件相比，使用乙酸作为纤维素接枝的新型绿色溶剂的反应系统将接枝密度提高了24倍。结果显示了溶剂性能之间的关系，羟基可及性和接枝产生纤维素植物纤维。该研究阐明了在化学修饰过程中通过控制纤维素植物纤维细胞壁的内部提供的机会，从而使纤维变为溶胀的纤维素纳米原纤维凝胶。