Synthesis of sugar‐based macromolecules via <scp>sono‐ATRP</scp> in miniemulsion
Izabela Zaborniak, Karolina Surmacz, Paweł Chmielarz
Abstract
Ultrasound‐mediated atom transfer radical polymerization (sono‐ATRP) in miniemulsion media is used for the first time for the preparation of complex macromolecular architectures by a facile two‐step synthetic route. Initially, esterification reaction of sucrose or lactulose with α‐bromoisobutyryl bromide (BriBBr) is conducted to receive multifunctional ATRP macroinitiators with 8 initiation sites, followed by polymerization of n ‐butyl acrylate (BA) forming arms of the star‐like polymers. The brominated lactulose‐based molecule was examined as an ATRP initiator by determining the activation rate constant ( k a ) of the catalytic process in the presence of a copper(II) bromide/tris(2‐pyridylmethyl)amine (Cu II Br 2 /TPMA) catalyst in both organic solvent and for the first time in miniemulsion media, resulting in k a = (1.03 ± 0.01) × 10 4 M −1 s −1 and k a = (1.16 ± 0.56) × 10 3 M −1 s −1 , respectively. Star‐like macromolecules with a sucrose or lactulose core and poly( n ‐butyl acrylate) (PBA) arms were successfully received using different catalyst concentration. Linear kinetics and a well‐defined structure of synthesized polymers reflected by narrow molecular weight distribution ( M w / M n = 1.46) indicated 105 ppm wt of catalyst loading as concentration to maintain controlled manner of polymerization process. 1 H NMR analysis confirms the formation of new sugar‐inspired star‐shaped polymers.