Investigating polymer blend miscibility with forward recoil spectrometry

We tested forward recoil spectrometry (FRES) as a method to determine misci bility by measuring coexistence compositions in binary polymer blends. In t his study, equilibrium phase compositions were determined for a composition ally symmetric poly(styrene-ran-methyl methacrylate) random copolymer (S-0. 49-r-MMA) and two homopolymers, deuterated polystyrene (dPS) and deuterated poly(methyl methacrylate) (dPMMA). Sample preparation, film dewetting, and beam damage were addressed, and the results for these polymer blends were in good agreement with those obtained through other experimental techniques . Deuteration had a strong effect on the miscibility of the dPS/S-0.49-r-MM A and dPMMA/S-0.49-r-MMA blends, to the extent that the asymmetric miscibil ity observed separately for the PS/S-0.49-r-MMA and PMMA/S-0.49- r-MMA blen ds was not found. Although this deuteration effect may limit the applicabil ity of FRES for some polymer systems, the accuracy with which phase composi tions can be determined with FRES makes it an attractive alternative to oth er less quantitative methods for investigating blend miscibility. (C) 2000 John Wiley & Sons, Inc.