Polystyrene, deuterated reflectivity measurements

Concentration profiles of PS graft chains were studied by a neutron reflection method [101]. Graft chains consisted of end-functionalized deuterated polystyrene. Although the measurement was not performed under the true equilibrium conformation, the observed metastable state was in good agreement with that predicted from the SCF theory. The kinetics of the penetration of graft chains into the polymer matrix was also investigated. 

Figure 6.9. Volume fraction profiles of an end-grafted polystyrene brush, of relative molecular mass 105 000, imder various solvent conditions (O, toluene at 21 C and cyclohexane at A, 53.4 °C , 31.5 °C o, 21.4 °C and A, 14.6 "C), deduced from neutron reflectivity measurements (all the solvents are deuterated). Toluene at 21 °C is a good solvent and the solid line is the classical parabolic profile. The theta temperature for d-cyclohexane is 34 °C and the dashed line is the elliptical profile predicted by analytical self-consistent field theory for theta conditions. After Karim et al. (1994).

Reflectivity measurements using the cell were first performed on a sample of amorphous deuterated polystyrene (dPS) in contact with low density polyethylene (LDPE) at 150C [19]. The characteristics of the polymers are given in Table I. This system had been chosen since it is one of only a few that contain semi-ciystalline polymers which have been reported in the literature. 

Ogawa H, Kanaya T, Nishida K, Matsuba G, Majewski JP, Watkins E. Time-resolved specular and off-specular neutron reflectivity measurements on deuterated polystyrene and poly( vinyl methyl ether) blend thin films during dewetting process. J Chem Phys 2009 131 104907. 

Figure 4.26. Interfacial broadening as a function of time for polyst5n-ene and deuterated polystyrene, both of relative molecular mass 200000, as measured by neutron reflectivity. Data taken at various temperatures have been reduced to a reference temperature of 120 C by using a WLF shift factor. After Karim et al. (1990).

Figure 7.9. Interfacial reinforcement of a polystyrene/poly(vinyl pyridine) interface by a high relative molecular mass deuterated styrene-vinyl pyridine block copolymer, with degrees of polymerisation of each block 800 and 870, respectively. Circles (right-hand axis) show the measured interfacial fracture energy as a function of the areal chain density of the block copolymer 2, whereas crosses show the fraction of dPS found on the polystyrene side of the interface after fiacture. The discontinuity in the curves at 2 = 0.03 nm is believed to reflect a transition from failure by chain scission to failure by crazing. After Kramer et al. (1994).

---