Multiple Morphologies of Self-Assembled Amphiphilic Poly(FOMA-b-EO) Diblock Copolymers

Abstract

A series of well defined semifluorinated diblock copolymers of poly(1H,1H-dihydroperfluorooctyl methacrylate)-block-polyethylene oxide (poly(FOMA-b-EO)) were used for the preparation of self-assembled structures. The morphologies of the poly(FOMA-b-EO) aggregates formed from solvent casting were investigated in terms of the copolymer composition, the concentrations of copolymer solutions, and the solvent type. From CHCl₃, the micellar film morphologies of poly(FOMA-b-EO_20k) were found to be well-ordered spherical and interconnected rods aggregates when PFOMA block sizes were 10 k (or 20 k) and 80 k. The aggregates were also found to depend strongly on the copolymer concentration. On the other hand, the morphological phase of block copolymeric micelles was inverted in trichlorofluoromethane (CFC-11) solution which is a good solvent for PFOMA, and aggregates were formed with PFOMA as a corona and PEO as a core. Morphological variations were also achieved by using different solvents such as N,N-dimethylformamide (DMF) and methanol, where the aggregates formed were vesicles and lamella with rods.

Keywords:

• amphiphilic block copolymers
• micelles
• self-assembly

Acknowledgments

This work was supported by the Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea government (MEST) (No. R01-2008-000-21056-0) and the second stage of BK21 Program.

Notes

^a 110°C, solvent : mixed solvent of trifluorotoluene and benzene (50:50 by weight).

^b Composition of poly(FOMA-b-EO) was determined by ¹H NMR.

^c Conversions were measured by gravimetric method.

^d m/n = weight ratio of PFOMA and PEO in the block copolymer.

NA*: No micelle formed.