Microphase Separation in Block-Random Copolymers of Styrene, 4-Acetoxystyrene, and 4-Hydroxystyrene

作者：Quinn Jeffrey D; Register Richard A^*

来源：Journal of Polymer Science Part B: Polymer Physics , 2009, 47(21): 2106-2113.

DOI：10.1002/polb.21807

• block copolymers
• copolymerization
• functionalization of polymers
• radical polymerization
• SAXS

"Block-random" copolymers-where one or more blocks are themselves random copolymers-offer a flexible modification to the usual block copolymer architecture. For example, in a poly(A)-poly(A-ran-B) diblock consisting of monomer units A and B, the interblock segregation strength can be continuously tuned through the B content of the random block, allowing the design of block copolymers with accessible order-disorder transitions at arbitrarily high molecular weights. Moreover, the development of controlled radical polymerizations has greatly expanded the palette of accessible monomer units A and B, including units with strongly interacting functional groups. We synthesize a range of copolymers consisting of styrene (S) and acetoxystyrene (AS) units, including copolymers where one block is P(S-ran-AS), through nitroxide-mediated radical polymerization. At sufficiently high molecular weights, near-symmetric PS-PAS diblocks show well-ordered lamellar morphologies, while dilution of the repulsive S-AS interactions in PS-P(S-ran-AS) diblocks yields a phase-mixed morphology. Cleavage of a sufficient fraction of the AS units in a phase-mixed PS-P(S-ran-AS) diblock to hydrogen-bonding hydroxystyrene (HS) units yields, in turn, a microphase-separated melt.

• 出版日期2009-11-1