Grafting of cellulose fibers latex by atom transfer radical polymerization

This study reported the synthesis of macro-initiator based on microfibers cellulose (MFC) from empty bunches (EFB), which was Ethyl α-bromoisobutyrate. The availability of the hydroxyl group on MFC offered a facile functionalization with Ethyl α-bromoisobutyrate to produce Bromo-ester group on MFC surface (MFC-BiB) that are known to be the excellent initiator for atom transfer radical polymerization (ATRP). As MFC provides only three hydroxyl groups per each unit of glucose with low reactivity, it is crucial to modify MFC with bromide functional groups having reactivity about 10.000 times greater than the hydroxyl group in the MFC. An MFC-BiB macro-initiator was successfully synthesized by homogeneous acetylation of cellulose with Ethyl α-bromoisobutyrate (EBiB) at 40°C. To confirm the performance MFC-BiB as macroinitiator, copolymerization between latex and MFC-BiB was conducted to produce Cellulose-g-latex by ATRP method with bipyridine/CuCl/CuCl₂ ligand as a complex catalyst and toluene/water as a mixed solvent. The degree of MFC-BiB substitution was measured by the FTIR method. The grafting copolymers were characterized by H-NMR and FTIR. The results indicated that the degree of substitution of macro-initiator at the ratio of MFC/EBiB of 1:3 and 1:6 were 1.27 and 1.28, respectively. The grafting efficiency of cellulose backbone with latex via ATRP showed a well-controlled grafting reaction at 44.5%.