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Starch‐g‐poly(phenyl acrylate) copolymers—synthesis, characterization, and physicochemical properties

Author:
Worzakowska, Marta
Source:
Die Stärke = 2017 v.69 no.11-12
ISSN:
0038-9056
Subject:
Fourier transform infrared spectroscopy, acid tolerance, composite polymers, gelatinization, glass transition temperature, nuclear magnetic resonance spectroscopy, physicochemical properties, potato starch, scanning electron microscopy, solvents, stable isotopes, starch
Abstract:
Synthesis, characterization, and physicochemical properties of some novel starch‐g‐poly(phenyl acrylate) copolymers are presented. The chemical modification of gelatinized potato starch by grafting with phenyl acrylate using K₂S₂O₈ as a radical initiator and employing different reaction conditions was studied in detail. Depending on the reaction conditions, the grafting parameters were changed, achieving their maximum values (grafting percent G: 41.8%, grafting efficiency GE: 82.3%) at 80°C under a reaction time of 150 min and starch to monomer ratio of 1:2. Spectroscopic methods (FTIR and ¹³C CP/MAS NMR) confirmed the successful formation of copolymers under the radical reaction of primary and secondary OH groups of starch and carbon–carbon double bonds of phenyl acrylate monomer. Scanning electron microscopy (SEM) indicated a non‐porous, rough, and heterogeneous structure of the copolymers. The blocking of some hydroxyl groups of starch by phenyl acrylate chains allowed more moisture resistant and more acid resistant copolymers to be compared, as compared to unmodified starch. Moreover, the copolymers were insoluble in polar and non‐polar solvents; however, they were able to undergo swelling. The range of swelling was dependent on the grafting parameters as well as the polarity of the solvents. According to DSC analysis, the copolymers exhibited a glass transition temperature of ca. 63–65°C and decomposed under two steps, which were directly connected with the degradation of starch and phenyl acrylate chains.
Agid:
5856268