Multiscale structural characterization of biocompatible poly(trimethylene carbonate) networks photo-cross-linked in a solvent

Poly(trimethylene carbonate) (PTMC) polymeric networks are biocompatible materials with potential biomedical applications. By combining Dynamic Mechanical Analysis (DMA), Solid State Nuclear Magnetic Resonance (NMR), and tensile testing, it was possible to fully characterize the inner structure and its relationship with the macroscopic properties of photo-crosslinked PTMC materials in a solvent medium. PTMC prepared from macromer with various molecular weights (3 kg/mol, 18 kg/mol, and 32 kg/mol) and with various polymer concentrations within the reactive media were analyzed, with the variation of thermomechanical properties and NMR signal decay characterized as a function of both aforementioned synthesis parameters. DMA and solid state Double Quantum (DQ) 1H NMR investigations demonstrated that the network crosslink density is directly related to the macromer molar mass and polymer concentration. More interestingly, tensile tests confirmed that mechanical behavior depended on the materials’ inner structure, notably their crosslink density. Specifically for the 18 kg/mol PTMC networks, dangling and free chains reinforced the network, exemplified by higher Young's modulus E values. This multiscale investigation provides a promising and precise approach to tailor the macroscopic behavior of PTMC materials, by controlling their specific inner network structural morphologies during synthesis.