The present article demonstrates the effects of molecular weight of network precursor on properties of solid-state polymer electrolyte membrane (PEM) comprised of poly (ethylene glycol) diacrylate (PEGDA) prepolymer, succinonitrile (SCN) plasticizer, and lithium bis(trifluoromethane sulphonyl) imide (LiTESI) salt using two different PEGDA molecular weights. To provide guidance for crosslinking reaction, ternary phase diagrams of the PEM precursor mixtures were established. Upon photopolymerization within the wide isotropic region, completely amorphous membranes were obtained in several compositions. The PEM having a higher PEGDA molecular weight (i.e., 6000 g/mol) revealed both improved impact strength with an elongation at break of similar to 80 % and higher ambient temperature ionic conductivity (similar to 1.4 x 10(-3) S cm(-1)) relative to the low molecular weight counterpart (i.e., 700 g/mol). Both PEMs exhibited excellent electrochemical (4.8 V/Li/Li+ and thermal (140 degrees C) stabilities. Specific discharge capacities of the PEM containing half-cells using LiFePO4 or Li4Ti5O12 electrodes against lithium electrode reached the level of 140 mAh g(-1) at 0.2 degrees C, indicating potential applications in all solid-state lithiumion batteries. (C) 2015 Elsevier B.V. All rights reserved.