IADR Abstract Archives
Thermo-mechanical Investigation of Photo-CuAAC Based Materials
Objectives: The objective of this research is to develop structure-property relationships for photo-initiated Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) based dental materials. It is hypothesized that photo-CuAAC is capable of alleviating key concerns associated with current methacrylate based materials. The step-growth polymerization along with the triazole adducts formed during polymerization afford a homogeneous network with high thermal and chemical stability. However, this technique requires investigation into thermo-mechanical structure property relationships of the polymers to determine if these materials are capable of providing a viable replacement to current methacrylate-based resins.
Methods: Monomeric component pairs with systematically varied structure were combined to create a series of step-growth network polymers. Thermomechanical behavior of photocured CuAAC films was investigated using dynamic mechanical analysis in tension mode. Storage modulus and tan δ were obtained with the limiting conversion glass transition temperature (Tg) determined from the peak maximum of the tan δ curve.
Results: Incorporating carbamate groups into the monomers showed a 49 oC increase in the polymeric Tg where inclusion of an aromatic component increased the Tg an average of 10 oC as a result of increased hydrogen bonding and π-π interactions, respectively. Additionally, the triazole moiety inherent to the CuAAC polymerization process shows a 40 oC increase in Tg when compared to a thiol-ene based analogue. Triazoles add rigidity to the polymer backbone and are capable of π-π interactions making this polymerization unique compared to all other “click” based materials. Overall, Tg values range from 18-90 oC owing to the tailorability of the monomers and polymerization process.
Conclusions: Photo-polymerized CuAAC networks achieve a range of mechanical properties through monomer design while alleviating specific drawbacks associated with chain-growth polymers. Optimization of the monomers is required to achieve a viable replacement to current restorative materials; however, these results demonstrate excellent potential associated with this novel polymerization process.
Methods: Monomeric component pairs with systematically varied structure were combined to create a series of step-growth network polymers. Thermomechanical behavior of photocured CuAAC films was investigated using dynamic mechanical analysis in tension mode. Storage modulus and tan δ were obtained with the limiting conversion glass transition temperature (Tg) determined from the peak maximum of the tan δ curve.
Results: Incorporating carbamate groups into the monomers showed a 49 oC increase in the polymeric Tg where inclusion of an aromatic component increased the Tg an average of 10 oC as a result of increased hydrogen bonding and π-π interactions, respectively. Additionally, the triazole moiety inherent to the CuAAC polymerization process shows a 40 oC increase in Tg when compared to a thiol-ene based analogue. Triazoles add rigidity to the polymer backbone and are capable of π-π interactions making this polymerization unique compared to all other “click” based materials. Overall, Tg values range from 18-90 oC owing to the tailorability of the monomers and polymerization process.
Conclusions: Photo-polymerized CuAAC networks achieve a range of mechanical properties through monomer design while alleviating specific drawbacks associated with chain-growth polymers. Optimization of the monomers is required to achieve a viable replacement to current restorative materials; however, these results demonstrate excellent potential associated with this novel polymerization process.