Photopolymerizable semi-crystalline polymers for thermally reversible, 3D printable cast molds

Objectives: This study demonstrates the use of photopolymerization to create semi-crystalline linear polymers suitable for thermally reversible materials in dental cast moldings produced from 3D printing. Methods: An aromatic diallyl, aliphatic dithiol chain extender, and monofunctional thiol were used in a photoinitiated system. The photopolymerization and crystallization kinetics as a function of chemistry and temperature were investigated using spectroscopy and calorimetry. These insights were used to realize vat photopolymerization-based 3D printing of functional objects that could be remotely melted and thereby removed using induction heating. Results: The addition of monothiol was shown to decrease the polymer molecular weight which correspondingly increased the crystallization rate. Photopolymerization kinetics are independent of temperature while crystallization was slowed as the temperature approaches the melting point of the materials. Through inclusion of chromium oxide, semicrystalline materials could be melted through induction heating. These materials were implemented in vat photopolymerization 3D printing to realize high-resolution objects that could be used as releasable dental molds following printing and induction heating. Significance: This work demonstrates a proof-of-concept methodology to realize directly printable, thermally reversible semicrystalline materials for potential use as dental molding materials.