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. chi(effc) and statistical segmental length, sigma, 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 chi(effc) and sigma 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, chi(effc) of the lithium-complexed PS-b-PMMA becomes less temperature-dependent due to the increase in chi(s) and decrease in chi(H).