It is well known that mechanical properties of PEGDA network and crystallization of PEG units depend on the molecular weight(Mw) between crosslinks (Mc). Covalent junctions constrain PEG chains, reducing melting temperature (Tm) and crystallinity, whereas dangling chains remain more mobile and crystallize more readily. Here, we synthesized networks using 1k PEGDA, a dithiol chain extender, and a 4-arm thiol crosslinker, varying their molar ratios to tune Mc. DSC provided crystallization temperature (Tc), Tm, and transition enthalpy to quantify crystallinity. Temperature-sweep rheology showed an ~3-order increase in storage modulus near Tc, evidencing crystal-derived physical crosslinks.
Overall, the PEGDA networks exhibited increasing Tm with increasing PEGDA Mw, and Tc shifted upward toward Tm as Mc increased. Based on these thermomechanical characteristics, we propose this crystalline PEGDA network as a candidate material for a tough bandage intended for tendon repair.