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Exploring Quality in Gradient Copolymers
Author(s) -
Elsen Andrea M.,
Li Yuanchao,
Li Qiaoxi,
Sheiko Sergei S.,
Matyjaszewski Krzysztof
Publication year - 2014
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.201300654
Subject(s) - copolymer , atomic force microscopy , materials science , molar mass distribution , polymer chemistry , catalysis , yield (engineering) , molecule , chemical engineering , polymer , chemistry , nanotechnology , composite material , organic chemistry , engineering
Quality of gradient copolymers is evaluated by atomic force microscopy (AFM) and correlated with molecular weight distribution (MWD) values. ARGET ATRP is employed with decreasing levels of catalyst concentrations to generate copolymers with increasingM ¯ w / M ¯ n values. The copolymers are transformed into molecular bottlebrushes to enable imaging and analysis of individual molecules by AFM. The average height (cross‐sectional) profile of all bottlebrushes agrees with the instantaneous composition (IC HEMA‐TMS ) of the analogous copolymer backbone, as determined by 1 H NMR. The copolymer synthesized with 500 ppm of catalyst exhibits more narrow distributions of both brush height and backbone length when analyzed as a bottlebrush by AFM. Correspondingly, the copolymers synthesized with lower catalyst concentrations yield bottlebrushes with broader height and length distribution. These results establish MWD values as an excellent trait to assess quality within gradient copolymers.