TY - JOUR
T1 - Micellar formation and organization in thin film polymer blends
AU - Chen, X. Chelsea
AU - Yang, Hengxi
AU - Green, Peter F.
PY - 2012/5/8
Y1 - 2012/5/8
N2 - We study the formation and organization of micelles, of polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) diblock copolymer chains, in thin film hosts composed of (1) blends of long and short chain polystyrenes, PS L and PS S, of degrees of polymerization P L and P S, respectively (P S < P L), and (2) blends of PS L and a homopolymer with which it is compatible, tetramethyl bisphenol-A polycarbonate (TMPC), of degree of polymerization P TMPC (P TMPC < P L). The role of competing entropic and enthalpic interactions on the block copolymer micelle formation and organization is examined. We show that the average size of the micelle cores, D core, decreased with increasing weight fraction of the shorter chain PS component in PS(P S = 125)/PS(P L = 15400) mixtures, for P L>N PS, N PS is the degree of polymerization of the PS block (the micelle corona). D core also decreased with increasing weight fraction of TMPC in TMPC(P TMPC = 122)/PS(P L = 15400) mixtures. The values of D core in the TMPC/PS L hosts were smaller than those in PS S/PS L mixtures, for the same TMPC, or PS S, weight fractions (P S ≈ P TMPC). This is due to more extensive mixing between the TMPC host chains, compared to the PS S chains, and the micelle corona. Furthermore, we show that the size and the organization of the micelles within the films may be controlled independently, through changing the relative fractions of PS S or TMPC and the value of P L. The fraction of TMPC, or PS S, mixed with the corona decreased as P L decreased from P L = 15400 to smaller values.
AB - We study the formation and organization of micelles, of polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) diblock copolymer chains, in thin film hosts composed of (1) blends of long and short chain polystyrenes, PS L and PS S, of degrees of polymerization P L and P S, respectively (P S < P L), and (2) blends of PS L and a homopolymer with which it is compatible, tetramethyl bisphenol-A polycarbonate (TMPC), of degree of polymerization P TMPC (P TMPC < P L). The role of competing entropic and enthalpic interactions on the block copolymer micelle formation and organization is examined. We show that the average size of the micelle cores, D core, decreased with increasing weight fraction of the shorter chain PS component in PS(P S = 125)/PS(P L = 15400) mixtures, for P L>N PS, N PS is the degree of polymerization of the PS block (the micelle corona). D core also decreased with increasing weight fraction of TMPC in TMPC(P TMPC = 122)/PS(P L = 15400) mixtures. The values of D core in the TMPC/PS L hosts were smaller than those in PS S/PS L mixtures, for the same TMPC, or PS S, weight fractions (P S ≈ P TMPC). This is due to more extensive mixing between the TMPC host chains, compared to the PS S chains, and the micelle corona. Furthermore, we show that the size and the organization of the micelles within the films may be controlled independently, through changing the relative fractions of PS S or TMPC and the value of P L. The fraction of TMPC, or PS S, mixed with the corona decreased as P L decreased from P L = 15400 to smaller values.
UR - http://www.scopus.com/inward/record.url?scp=84860771136&partnerID=8YFLogxK
U2 - 10.1021/ma300194d
DO - 10.1021/ma300194d
M3 - Article
AN - SCOPUS:84860771136
SN - 0024-9297
VL - 45
SP - 3993
EP - 4000
JO - Macromolecules
JF - Macromolecules
IS - 9
ER -