Can the hydrophilicity of functional monomers affect chemical interaction?

The number of carbon atoms and/or ester/polyether groups in spacer chains may influence the interaction of functional monomers with calcium and dentin. the present study assessed the chemical interaction and bond strength of 5 standard-synthesized phosphoric-acid ester functional monomers with different spacer chain characteristics,by atomic absorption spectroscopy (aas),atr-ftir,thin-film x-ray diffraction (tf-xrd),scanning electron microscopy (sem),and microtensile bond strength (μtbs). the tested functional monomers were 2-mep (two-carbon spacer chain),10-mdp (10-carbon),12-mddp (12-carbon),mtep (more hydrophilic polyether spacer chain),and cap-p (intermediate hydrophilicity ester spacer). the intensity of monomer-calcium salt formation measured by aas differed in the order of 12-mddp=10-mdp>cap-p>mtep>2-mep. ftir and sem analyses of monomer-treated dentin surfaces showed resistance to rinsing for all monomer-dentin bonds,except with 2-mep. tf-xrd confirmed the weaker interaction of 2-mep. highest μtbs was observed for 12-mddp and 10-mdp. a shorter spacer chain (2-mep) of phosphate functional monomers induced formation of unstable monomer-calcium salts,and lower chemical interaction and dentin bond strength. the presence of ester or ether groups within longer spacer carbon chains (cap-p and mtep) may affect the hydrophilicity,μtbs,and also the formation of monomer-calcium salts. © international & american associations for dental research.