Objective: It is desirable for a restorative dental material to have bioactive and bonding properties. Nano-hydroxyapatite (n-HAp) can bind chemically to enamel and dentine. The aim is to synthesise a novel n-HAp/polyurethane (PU) based-composite by physical/chemical mixing (PM/CM) techniques and investigate their bonding characteristics. Methods: n-HAp was synthesised by sol-gel technique. PM: PU was synthesised by using polytetramethylene glycol (PTMG: Sigma Aldrich USA), 4,4Œ-methylenebis(phenyl isocyanate) (MDI: Sigma Aldrich USA), 1,4-butanediol (BD: Sigma Aldrich USA). After synthesis PU was dissolved in tetrahydrofuran (Sigma Aldrich USA) and n-HAp was added and stirred for 48hrs at room temperature. CM
1: n-HAp was added to the PTMG before MDI and BD were added. After mixing n-HAp/PU were allowed to polymerise at high temperature to make a composite. CM
2: n-HAp was added to the unpolymerised PU and allowed them to polymerise at high temperature. The resulting n-HAp/PU composites were characterised by FTIR spectroscopy, SEM, and UV-spectroscopy. Results: The FTIR spectrum for n-HAp had a characteristic hydroxyl (OH) stretching peak at 3570cm
-1 and for PU, NH peak at 3297cm
-1. For the synthesised composites, using the three procedures, the spectrum had a combined peak in the range of 3330cm
-1, which was likely to be the grafted peak of HN-CO (linkage of OH and NCO), showing that covalent bond was formed between n-HAp and PU. There was also grafting at OP-HC-O-(linkage of PO
4 and CH
2-O-CH
2) in the range of 1110-900cm
-1. SEM was showing the distribution of n-HAp in composite. UV-spectra peak of composite was shift to 360-400nm showing the incorporation of n-HAp in the structure of PU.
Conclusion: Covalent bond was formed between n-HAp and PU through HN-CO and OP-HC-O grafting without intermediate coupling agent. Hence this composite has the potential to be developed as a novel-bioactive dental restorative material with better biological and physical properties.