N-isopropylacrylamide (NIPAAm) copolymers were prepared to explore the possibilities of forming responsive fibers. Acrylic acid (AA), methacrylic acid (MAA), acrylamide (AAm), acrylonitrile (AN), methyl methacrylate (MMA), and vinyl acetate (VAc) were copolymerized with NIPAAm and the products were characterized by GPC; ¹H-NMR, IR, DSC, and TGA. Extrudates were prepared to evaluate the possibilities of utilization of the copolymers in fiber applications. The copolymerization of NIPAAm with the various comonomers at a molar feed ratio of 1 : 1 were carried out using AIBN as initiator in N,N'-dimethylformamide at a total monomer concentration of 20% (wt.). The monomer composition of the prepared copolymers evaluated by elemental analysis suggested that approximately 1 : 1 copolymers were formed in the case of poly(NIPAAm-co-AA), poly(NIPAAm-co-AAm), and poly(NIPAAm-co-MAA). The glass transition temperatures of the copolymers determined by DSC analysis were in the range, 110∼170 ℃. In the case of the copolymers having carboxylic acid groups, endothermic peaks in the range of 160∼200 ℃ appeared in the DSC thermograms, which appear to be due to anhydride formation via dehydration. Above this temperature the copolymers were stable up to 340 ℃. In the case of poly(NIPAAm-co-AA), poly(NIPAAm-co-AN), poly(NIPAAm-co-MAA), and poly(NIPAAm-co-MMA), extrudates could be prepared by injecting concentrated solutions of the copolymers into a nonsolvent coagulating bath. Among these, poly(NIPAAm-co-MAA) and poly(NIPAAm-co-AN) appear to be most promising in the preparation of PNIPAAm copolymer fibers.