TY - JOUR
T1 - Poly(methyl methacrylate)-block-poly(n-butyl methacrylate) Diblock Copolymer Micelles in an Ionic Liquid
T2 - Scaling of Core and Corona Size with Core Block Length
AU - Ma, Yuanchi
AU - Lodge, Timothy P.
N1 - Publisher Copyright:
© 2016 American Chemical Society.
PY - 2016/5/10
Y1 - 2016/5/10
N2 - The structure of poly(methyl methacrylate)-block-poly(n-butyl methacrylate) (PMMA-b-PnBMA) micelles in the room temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]), a selective solvent for the PMMA block, has been studied using dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS). A series of seven PMMA-b-PnBMA diblock copolymers were prepared by reversible addition-fragmentation chain-transfer (RAFT) polymerization, in which the degree of polymerization of the PMMA block was kept constant while the PnBMA block length was varied. All the polymers formed spherical micelles at ambient temperature in dilute solution; their hydrodynamic radius (Rh) and core radius (Rc) were obtained by DLS and SAXS, respectively. It was found that Rc and the degree of polymerization of the core block, NB, followed a power law relationship in which Rc ∼ NB0.71±0.01. The corona thickness (Lcorona), given by the difference of Rh and Rc, does not show any apparent dependence on NB. These results were compared to scaling theory, and were found to be only in partial agreement with the star model proposed by Halperin et al. However, the mean-field calculations of micellar dimensions by Nagarajan and Ganesh were in excellent agreement with the data. This comprehensive experimental study provides precise quantification of the Rc and Lcorona dependence on core block lengths, due to the use of seven different block copolymers with identical corona block lengths.
AB - The structure of poly(methyl methacrylate)-block-poly(n-butyl methacrylate) (PMMA-b-PnBMA) micelles in the room temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]), a selective solvent for the PMMA block, has been studied using dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS). A series of seven PMMA-b-PnBMA diblock copolymers were prepared by reversible addition-fragmentation chain-transfer (RAFT) polymerization, in which the degree of polymerization of the PMMA block was kept constant while the PnBMA block length was varied. All the polymers formed spherical micelles at ambient temperature in dilute solution; their hydrodynamic radius (Rh) and core radius (Rc) were obtained by DLS and SAXS, respectively. It was found that Rc and the degree of polymerization of the core block, NB, followed a power law relationship in which Rc ∼ NB0.71±0.01. The corona thickness (Lcorona), given by the difference of Rh and Rc, does not show any apparent dependence on NB. These results were compared to scaling theory, and were found to be only in partial agreement with the star model proposed by Halperin et al. However, the mean-field calculations of micellar dimensions by Nagarajan and Ganesh were in excellent agreement with the data. This comprehensive experimental study provides precise quantification of the Rc and Lcorona dependence on core block lengths, due to the use of seven different block copolymers with identical corona block lengths.
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U2 - 10.1021/acs.macromol.6b00315
DO - 10.1021/acs.macromol.6b00315
M3 - Article
AN - SCOPUS:84969663948
SN - 0024-9297
VL - 49
SP - 3639
EP - 3646
JO - Macromolecules
JF - Macromolecules
IS - 9
ER -