Ion-Complexation-Induced Changes in the Interaction Parameter and the Chain Conformation of PS-b-PMMA Copolymers

Small-angle neutron scattering (SANS) was used to study the changes of segmental interactions and chain conformation due to the formation of lithium−PMMA complexes in polystyrene- block -poly(methyl methacrylate) (PS- b -PMMA) copolymers as a function of temperature and the percentage of carbonyl groups coordinated with lithium ions. χ effc and statistical segmental length, σ, are derived from the SANS profiles of the copolymers with lithium−PMMA complexes in a disordered state by use of the correlation-hole scattering formalism described by Leibler. Fitting results show that both χ effc and σ of PS and PMMA increase as the formation of lithium−PMMA complexes in PS- b -PMMA copolymers, and the degree of such increase depends on the concentration of lithium−PMMA complexes. In addition, χ effc of the lithium-complexed PS- b -PMMA becomes less temperature-dependent due to the increase in χ s and decrease in χ H .