Flower micelle of amphiphilic random copolymers in aqueous media.
The structure of the flower micelle formed by an amphiphilic random copolymer, sodium (2-acrylamido)-2-methylpropanesulfonate and N-dodecylmethacrylamide p(AMPS/C12), in 0.05 M aqueous NaCl was investigated by fully atomistic molecular dynamics simulation as well as by light scattering, and the results were compared with the flower micelle model of the minimum loop size, recently proposed by Kawata et al. [Macromolecules 2007, 40, 1174-1180]. After a sufficiently long simulation time, simulated p(AMPS/C12) chain with the degree of polymerization of 200 and C12 content of 50 mol % formed a unicore micelle, of which radius of gyration was much smaller than the AMPS homopolymer with the same degree of polymerization. The simulated micellar structure was analyzed in terms of density distribution functions for dodecyl groups, the main chain, and sulfonate groups as functions of the radial distance r from the center of mass of dodecyl groups. Only dodecyl groups exist at r less, similar 1.5 nm, and the main chain and sulfonate groups distribute in the range of r between 1.5 and 3.5 nm, but there were dodecyl groups coexisting with the main chain and sulfonate groups beyond r = 1.5 nm. All these structural features, as well as hydrodynamic radius data for p(AMPS/C12) with C12 contents higher than ca. 20 mol % obtained by light scattering, agreed with the predictions of the flower micelle model of the minimum loop size.
Tominaga
Yukio
Y
Genomic Science Laboratories, Dainippon Sumitomo Pharma Co., Ltd., 33-94 Enoki, Suita, Osaka 564-0053, Japan.
Mizuse
Mari
M
Hashidzume
Akihito
A
Morishima
Yotaro
Y
Sato
Takahiro
T
D000178:Acrylamides / Q000737:chemistry; D017738:Alkanesulfonic Acids / Q000737:chemistry; D008823:Micelles; D056004:Molecular Dynamics Simulation; D011108:Polymers / Q000737:chemistry*; D014867:Water / Q000737:chemistry
D000178:Acrylamides; D017738:Alkanesulfonic Acids; D008823:Micelles; D011108:Polymers; D014867:Water; C068559:propylsulfonic acid; C045985:methacrylamide