There is a tremendous interest in human cardiomyocytes generated from patient-derived induced pluripotent stem cells (iPSC-CMs) for the study and possible treatment of human heart diseases. Despite their vast potential, a significant impediment to a broader application of iPSC-CMs to study human myocyte biology is the structural and functional immaturity of iPSC-CMs. Growing evidence indicates that synthetic polymers utilized as extracellular substrates can exert significant effects on in vitro tissue generation, although the underlying mechanisms remain largely unknown. Based on the profound impact of the extracellular matrix of developing embryos on in vivo organogenesis, we hypothesize that engineered polymer substrates will likewise influence in vitro maturation of iPSC-CMs. A subset of combinatorial polymers was synthesized by polymerizing poly(ε-caprolacton) (PCL), polyethylene glycol (PEG), and carboxylated PCL (cPCL), abbreviated as x%PEG-y%PCL-z%cPCL (x, y, and z: molar %). We investigated effects of the polymer composition on maturation of iPSC-CMs with respect to the beating behavior, mitochondrial function and molecular profiles after 30 days in culture on polymer scaffolds. Results showed the 4%PEG-96%PCL scaffold promoted the most active beating in iPSC-CMs at 30 days and further, that the mitochondrial function, as assessed by tetramethyl rhodamine methylester (TMRM) was significantly increased in the iPSC-CMs cultured on 4%PEG-96%PCL over other polymers. Molecular profiling analysis indicates 4%PEG-96%PCL scaffolds enhanced the expression of MYL2 (a commonly accepted marker of mature ventricular myocytes) as well as of components of the intermediate filaments linking the plasma membrane to the myofilament. In summary, although the polymers we used here exhibit similar physicochemical properties, they have divergent effects on iPSC-CM differentiation. Thus, specific chemical compositions of synthetic substrates can exert profound influence on in vitro maturation of hiPSC-CMs. Our work exploring the effects of synthetic biomaterials on human stem cell differentiation could pave the way for a successful translation of ongoing advances in tissue engineering to new treatments for human heart diseases.