Development of PCLMA/HAp-Si composite resin for vat photopolymerization 3D printing

A photopolymerizable composite resin based on polycaprolactone methacrylate (PCLMA) was developed with functionalized hydroxyapatite (HAp-Si) to enhance the phase affinity between the polymer matrix and inorganic filler, thereby creating a stable resin suitable for 3D printing. Hydroxyapatite was functionalized with 3-aminopropyltrimethoxysilane (APTES) to produce HAp-Si, as confirmed by Fourier Transform Infrared Spectroscopy (FTIR). Polycaprolactone diol (PCLdiol) was successfully modified into PCLMA through the substitution of hydroxyl groups with methacrylate groups, as confirmed by FTIR, which also resulted in an increase in the number-average molecular weight (Mn). Scanning Electron Microscopy (SEM) images confirmed well-dispersed HAp agglomerates, while grafting improved filler distribution within the matrix. Additionally, the resin displayed good dimensional fidelity in 3D printing of cylindrical samples measuring 6.35 x 12.70 mm. These findings suggest that PCLMA-based composite resins are suitable for 3D printing via vat photopolymerization.