Random copolymer/homopolymer interfacial widths as a function of copolymercomposition

Neutron reflectivity experiments were performed on bilayer samples to deter mine interfacial widths between poly(styrene-mn-methyl methacrylate) copoly mers (P[S-ran-MMA]) and deuterated polystyrene (dPS) or deuterated poly(met hyl methacrylate) (dPMMA) as a function of copolymer composition. The copol ymer composition, f(s), varied from 0.49 to 0.85 mol% styrene. After a 4 h anneal at 150 degrees C, the interfacial width between the compositionally symmetric random copolymer (f(s) = 0.49) and dPS was smaller than with dPMM A. Equal interfacial widths for the copolymer with dPS and with dPMMA was f ound at [f(s)] approximate to 0.6. These reflectivity results are consisten t with work by Kulasekere et al. and are discussed in relation to our previ ously published results on the fracture toughness of PS/PMMA joints reinfor ced with P[S-mn-MMA]. (C) 1999 Elsevier Science Ltd. All rights reserved.