Synthesis and crystallization-induced microphase separation of cellulose triacetate-block-poly(γ-benzyl-l-glutamate)

This article describes the first observation of crystallization-induced microphase separation in thin film and bulk cellulose triacetate-block-poly(gamma-benzyl-l-glutamate) (PBLG) [cellulose triacetate (CTA)-b-PBLG] via copper-catalyzed azide-alkyne cycloaddition (CuAAC) between azido-functionalized CTA at the reducing end and alkyne-functionalized PBLG at the C-terminus. The reactivity of the amino group at the C-1 position of the glucosyl residue at the reducing end for the initiation reaction of the ring-opening polymerization (ROP) of gamma-benzyl-l-glutamate N-carboxyanhydride was compared to that of the azido group at the reducing end of CTA for CuAAC, with PBLG bearing an alkyne group at the C-terminus. Although the amino group at the reducing end of CTA exhibited no reactivity as a macroinitiator for ROP of BLG, the azido group at the reducing end of CTA reacted with the alkyne group at the C-terminus of PBLG to afford CTA-b-PBLG. The structure of CTA-b-PBLG was characterized by H-1- and C-13-nuclear magnetic resonance spectroscopies, infrared spectroscopy, differential scanning calorimetry, and wide angle X-ray diffractometry. Microphase separation of the film and bulk of CTA-b-PBLG was clearly shown by atomic force microscopy, field-emission scanning electron microscopy, and transmission electron microscopy.