Micellar formation and organization in thin film polymer blends

X. Chelsea Chen, Hengxi Yang, Peter F. Green

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

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.

Original languageEnglish
Pages (from-to)3993-4000
Number of pages8
JournalMacromolecules
Volume45
Issue number9
DOIs
StatePublished - May 8 2012
Externally publishedYes

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