Combinatorial libraries of segmented polyurethaneurea with gradients in curing temperature were prepared and characterized using a novel high-throughput mechanical instrument. Stress/strain profiles were taken at different temperature positions on the libraries, and a structure/property relationship between microstructure and mechanical properties was established by correlating the measured strength and strain at break to high-throughput AFM and FT-IR measurements on the same library. These results demonstrate the feasibility of rapid and accurate screening of mechanical properties, and their correlation to structure, by using gradient combinatorial polymer libraries.