Linear and star-branched polyoxybenzoate-polyoxyphenoxybenzoate copolymers (POB-co-POPB) at a 65/35 molar ratio were synthesized via melt acidolysis using AB-type monomers and branching agents. By controlling the molecular weight and topology of these polymers, both melt processability and solid-state CO2 gas absorption behavior were enhanced. POB-POPB copolymers with a molar ratio 65/35 showed a glass transition of 143-degrees-C and completion of melting at ca. 300-degrees-C. POB-POBP copolymers with a systematically increasing branching agent content showed a systematically decreasing peak intensity in wide-angle X-ray diffraction, indicating that increasing branch-point concentration leads to a decrease in liquid-crystal ordering. Star-branched POB-POPB copolymers showed greatly enhanced carbon dioxide gas absorption behavior relative to their linear counterparts. Whereas CO2 blown foams of linear POB-co-POPB produced by the gas supersaturation technique had a relatively high density and showed highly anisotropic bubble growth, well-defined, nearly isotropic foams of star-branched POB-co-POPB with a mean cell size from 200 to 400 mu were made using the gas supersaturation technique. Structural features were characterized via scanning electron microscopy, and mechanical properties were determined by indentation testing with a 0.25 in. ball indenter. These LCP foams exhibit relative mechanical properties similar to polystyrene and microcellular polycarbonate foams. A strong inverse relationship was noted between cell size and modulus for liquid crystalline foams with a cell size below 400 mum.