To assess the materials characterization after 3D printing and to determine their physical and chemical properties, molecular weights were characterized using two methods. First, gel permeation chromatography (GPC, Waters Corporation, Milford, MA, United States) using dichloromethane as a mobile phase and polystyrene standards was utilized to determine the weight average molecular weight (Mw), number average molecular weight (Mn), and polydispersity index (PDI), which is the ratio of Mw/Mn used to indicate the distribution of molecular weight within a sample. Dilute solution inherent viscosity (IV) was determined using a Cannon-Fenske U-viscometer at 20°C at a concentration of 0.1 mg/mL in chloroform. In cases of materials containing β-TCP, samples were first separated to remove ceramic particulate and isolate the polymer being analyzed.

Thermal profiles were evaluated by differential scanning calorimetry (DSC) using a Perkin Elmer Pyris DSC (Waltham, MA, United States). Samples of 4–10 mg were weighed and placed in hermetically sealed aluminum pans and heated from 20 to 240°C at a heating rate of 20°C/min. Thermograms were analyzed for glass transition temperature (Tg), peak melting temperature (Tm) and heat of fusion (ΔHf), all of which were calculated directly using the onboard software.

Gas chromatography was performed on a Claris 580 system (Perkin Elmer, Waltham, MA, United States) equipped with a flame ionization detector, using helium as the carrier gas, and used to quantify the level of residual monomer using a direct injection technique. Samples were first dissolved in hexafluoro-2-propanol (HFIP) solvent and directly injected into the column. Individual peaks were matched with retention times and calibration curves of matching monomer standards (lactide, caprolactone, and TMC) to determine individual and sum total monomer residuals in the dissolved sample. In cases of materials containing β-TCP, samples were first separated to remove ceramic particulate and isolate the polymer being analyzed.

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