With the advent of systematically designed controllable reversible addition fragmentation termination (CRAFT) compounds, we have identified structure property relationships related to the RAFT compositional structure as it impacts photoplasticity in covalent adaptable networks (CANs). In this study, we have expanded the range and functional capabilities of addition fragmentation capable network forming monomers by synthesizing and evaluating systematically varying CRAFT monomers with the general formula ABCBA. Subsequent assessment of the impact of these monomers on photoplasticity and stress relaxation was performed. Structural variation of the A and B segments, in particular, imparts increased efficiency and efficacy in stress relaxation and photoplasticity. The CRAFT monomers employed have highly efficient stress relaxation properties demonstrating stress reduction of up to 54% and 75%, respectively, in postpolymerization network photoplasticity experiments. Furthermore, polymerization stress reduction in purely acrylate and acrylate thiol networks with CRAFT monomers shows a remarkably enhanced efficacy with the inclusion of relatively small amounts of the monomers. With a loading of only 1.5 wt % of the alkene trithiocarbonate monomer in each system more than 75% stress reduction was achieved.