TY - JOUR
T1 - Control of Solution Phase Behavior through Block-Random Copolymer Sequence
AU - Taylor, Lauren W.
AU - Priestley, Rodney D.
AU - Register, Richard A.
N1 - Publisher Copyright:
© 2024 American Chemical Society.
PY - 2024/2/13
Y1 - 2024/2/13
N2 - The phase behavior of polymers in solution is of both fundamental and practical interest. Previous work using coarse-grained molecular simulations suggests that the critical temperature (Tc) of macromolecules in solution can be controlled by the monomer sequence. Here, we experimentally investigated the solution phase behavior of a series of styrene-isoprene copolymers in both styrene- and isoprene-selective solvents. Across the series, the copolymers had a similar overall composition and molecular weight but subtle changes in the monomer sequence obtained by systematically placing a short homopolymer block of either polystyrene or polyisoprene at the end or the center of an otherwise random styrene-isoprene copolymer chain. Compared with a fully random copolymer, sequences that microphase-separate to form starlike or crew-cut micelles produce a lower Tc. Conversely, sequences that do not form micelles exhibit a higher Tc. Through a delicate balance of solvent/polymer compatibility, we demonstrate the spontaneous and thermoreversible formation of unusually large (aggregation number, ∼1000), stable crew-cut micelles. Despite the unusual structure, the thermodynamics of formation of these crew-cut micelles is similar to that of starlike block copolymer micelles.
AB - The phase behavior of polymers in solution is of both fundamental and practical interest. Previous work using coarse-grained molecular simulations suggests that the critical temperature (Tc) of macromolecules in solution can be controlled by the monomer sequence. Here, we experimentally investigated the solution phase behavior of a series of styrene-isoprene copolymers in both styrene- and isoprene-selective solvents. Across the series, the copolymers had a similar overall composition and molecular weight but subtle changes in the monomer sequence obtained by systematically placing a short homopolymer block of either polystyrene or polyisoprene at the end or the center of an otherwise random styrene-isoprene copolymer chain. Compared with a fully random copolymer, sequences that microphase-separate to form starlike or crew-cut micelles produce a lower Tc. Conversely, sequences that do not form micelles exhibit a higher Tc. Through a delicate balance of solvent/polymer compatibility, we demonstrate the spontaneous and thermoreversible formation of unusually large (aggregation number, ∼1000), stable crew-cut micelles. Despite the unusual structure, the thermodynamics of formation of these crew-cut micelles is similar to that of starlike block copolymer micelles.
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U2 - 10.1021/acs.macromol.3c02111
DO - 10.1021/acs.macromol.3c02111
M3 - Article
AN - SCOPUS:85183183806
SN - 0024-9297
VL - 57
SP - 916
EP - 925
JO - Macromolecules
JF - Macromolecules
IS - 3
ER -