Commercial organic matrixes of dental composites generally include diluents such as triethylene glycol dimethacrylate (TEGDMA) to reduce viscosity. However, the diluent exhibits adverse effects such as curing shrinkage and diminished mechanical properties of the dental composites. To overcome these adverse effects, organic monomers that can be used as an organic matrix may be developed. In this study, various novel organic monomers were developed by substituting alkoxy for hydroxyl groups in 2,2-bis[4-(2-hydroxy-3-methacryloyloxy propoxy)phenyl]propane (bis-GMA). Viscosities of the alkoxy-substituted monomers were decreased by increasing substituent size. The viscosity of 2,2-bis[4-(2-ethoxy-3-methacryloyloxy propoxy)phenyl]propane (bis-E-GMA) was higher than the control organic matrix (70 wt % bis-GMA and 30 wt % TEGDMA). However, those of 2,2-bis[4-(2-propoxy-3-methacryloyloxy propoxy)phenyl]propane (bis-Pr-GMA), 2,2-bis[4-(2-butoxy-3-methacryloyloxy propoxy)phenyl]propane (bis-B-GMA), and 2,2-bis[4-(2-pentoxy-3-methacryloyloxy propoxy)phenyl]propane (bis-P-GMA) were lower than the control organic matrix. To this end, these monomers could be used as organic matrixes of dental composites without an additional diluent. Among these monomers, bis-B-GMA exhibited the lowest curing shrinkage. In comparison to the control organic matrix, the curing shrinkage of the bis-B-GMA dental composite was approximately 40%. Additionally, dental composites prepared from bis-B-GMA exhibited excellent mechanical properties.