Introduction: The World Health Organization report from 2022 points to caries being a meaningful problem worldwide. Such a state results from poor oral hygiene, huge sugar consumption and the effect of oral bacterial metabolism. The treatment of caries is based on the removal of the affected tissue and filling the cavity with dental filling. The disadvantage of this solution is the lack of antibacterial activity of dental fillings, which may result in secondary caries. The materials used in dental fillings can be modified with compounds possessing quaternary ammonium groups to achieve microbiocidal properties.
This research aims to synthesize novel dimethacrylate monomers possessing two quaternary ammonium groups. The novelty of this study was the use of two cycloaliphatic diisocyanates in the synthesis of these compounds–isophorone diisocyanate (IPDI) and 4,4′-methylenebis(cyclohexyl isocyanate) (CHMDI).

Methods: A three-step procedure was utilized to obtain the novel monomers:
I. Transesterification of MMA;
II. N-alkylation of semi-product with 1-bromododecane;
III. Addition of a second semi-product to diisocyanate.
The chemical structures of the obtained monomers were confirmed with ¹H and ¹³C NMR and FTIR spectroscopy.

Results: The synthesis resulted in two novel monomers—QA12+IPDI and QA12+CHMDI—which are viscous, yellowish liquids. ¹H and ¹³C NMR and FTIR spectroscopy confirmed the structures of the obtained monomers.

Conclusions: The spectroscopy methods confirmed the structures of our novel monomers. Future research will be focused on the characterization of these monomers’ properties.