Design of Experiments Analysis of Flame Sprayed PCL/PMMA Bioactive Coatings

Bioactive coatings are proven to enhance bone regeneration, implant integration and act as drug-delivery systems following bone replacement surgeries.

Polycaprolactone (PCL) was used in this study as coating material due to its superior biocompatibility and biodegradability.  Polymethylmethacrylate (PMMA) was used as an additive in order to improve the flowability of the PCL powder. The processing technique used to obtain polymeric coatings was oxy-acetylene flame spraying. Thermal spraying was preferred due to its superior mechanical advantages over other techniques.

Seeing that biodegradable polymers were not thoroughly investigated in the past, a Design of Experiments (DoE) analysis was necessary in order to understand the effects of spraying parameters on coating characteristics (thickness, roughness, adhesion, wettability) and to be able to optimise the coating properties for specific requirements. The polymers were sprayed onto titanium substrates. The statistical analysis was followed by FTIR spectroscopy, which showed that the coatings underwent little chemical degradation. The levels of pH, conductivity and weight loss of the polymer coatings were also monitored over a period of 31 days. Finally, biocompatibility tests showed that cells proliferated well on flame sprayed polymer coatings, which confirms that the coating technique used did not affect the biological performance of the material.