Chain-growth polycondensation via the substituent effect: Investigation in to the role of initiator and base on the synthesis of poly(N-octyl benzamide)

A detailed investigation into the role of initiator structure, the presence of an initiator, and basicity of the non-nucleophilic base in the chain-growth condensation (CGC) synthesis of poly(N-octyl benzamide) was conducted. A series of phenyl ester dimethyl amide initiators with different leaving groups were synthesized and used in the CGC preparation of poly(N-octyl benzamide). Additional polymerizations were conducted without the presence of an initiator and with different non-nucleophilic bases. Kinetic studies, along with nuclear magnetic resonance spectroscopy and gel-permeation chromatography, were used to determine progress of the reaction, molecular weights, and molecular weight distributions. The experimental and computational results demonstrated that initiators containing electron-withdrawing substituent phenyl esters, such as the p-nitrophenyl ester, and electron-withdrawing carbonyl character on the parent benzoate produce polymers with controllable molecular weights and narrow molecular weight distributions. Whereas, initiating species that contain electron-donating character on the benzoate backbone, such as dimethylamino and methyl ester groups, produce polymers that resemble the results from reactions involving no initiators at all, indicating poor polymerization control.