Cellulose nanocrystals grafted with polyacrylamide assisted by macromolecular RAFT agents

Graft modification is an excellent way to prepare cellulose nanocrystals (CNCs) with various functions. In this work, different water-soluble macro reversible addition fragmentation chain transfer (macroRAFT) agents were used to mediate grafting of polyacrylamide with cellulose nanocrystals. Fourier-transform infrared spectroscopy, 13 C solid-state nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy, and elemental analysis were used to characterize the presence of polyacrylamide and quantify its content on the modified cellulose nanocrystals. The results show that two amphiphilic macroRAFTs, namely St 5 AA 14 RAFT and St 7 AA 14 RAFT, increased the weight ratio of polyacrylamide on the modified cellulose nanocrystals, whereas a corresponding hydrophilic macroRAFT (AA 14 RAFT) impeded growth of the polymer chains on the cellulose nanocrystals. Examination of the structure of the graft products and the cleaved polyacrylamide chains revealed that the amphiphilic macroRAFTs were involved in the graft reaction through effective chain transfer, thereby increasing the weight ratio of polyacrylamide on the modified CNCs.