Synthesis of regioselective starch-based macroinitiators at molecular level

Regioselective starch-based macroinitiators, such as 2,3,6-O-macroinitiator (2,3,6-O-starch-2-bromoisobutyrate), 2-O-macroinitiator (2-O-starch chloroacetate), 6-O-macroinitiator (6-O-starch-3-chloropivalate), 3-O-macroinitiator (3-O-starch-2-bromoisobutyrate), 3,6-O-macroinitiator (3,6-O-starch-2-bromoisobutyrate), and 2,3-O-macroinitiator (2,3-O-starch-2-bromoisobutyrate), were successfully synthesized at the molecular level. 13 C NMR spectra were employed to certify the structures of these regioselective macroinitiators. Their thermal behaviors characterized by TGA and DSC indicated the destruction of hydrogen bonds and the crystalline structure during the dissolution and reaction processes. The solubility of macroinitiators depended on their degree of substitution (DS).