A comparative study on grafting polymers from cellulose nanocrystals via surface-initiated atom transfer radical polymerization (ATRP) and activator re-generated by electron transfer ATRP.

Both Surface-Initiated Atom Transfer Radical Polymerization (SI-ATRP) and Surface-Initiated Activator Re-Generated by Electron Transfer ATRP (SI-ARGET ATRP) were performed to graft polystyrene and poly(4-vinylpyridine) on the surface of cellulose nanocrystals (CNCs) to evaluate the potential benefits of each method. The polymer grafted CNCs and their corresponding free polymers initiated from sacrificial initiators were characterized by Fourier transform infrared spectroscopy, gel permeation chromatography, dynamic light scattering, differential scanning calorimetry, thermogravimetric analysis, and elemental analysis, respectively. It was found that SI-ARGET ATRP favored the grafting of longer polymer chains with lower grafting density compared with the classical SI-ATRP. The surface initiation efficiency of brominated CNCs in SI-ARGET ATRP is much lower than that in SI-ATRP, which is mainly due to the much lower amount (ppm level) of catalysts and faster propagation rate in SI-ARGET ATRP system.