Dental professionals are seeing a growing population of patients with visible signs of
dental erosion. The approach currently being used to address the problem typically leverages the enamel protection benefits of
fluoride. In this report, an alternative new block copolymer with a hydrophilic
polyacrylic acid (PAA) block and a hydrophobic
poly(methyl methacrylate) (
PMMA) block was developed to similarly reduce the
mineral loss from enamel under acidic conditions. This series of
PMMA-b-PAA block copolymers was synthesized by reversible addition fragmentation transfer (RAFT) polymerization. Their structures were characterized by gel permeation chromatography (GPC) and (1)H nuclear magnetic resonance (NMR) spectra. The molar fractions of
acrylic acid (AA) in the final block copolymer were finely controlled from 0.25 to 0.94, and the molecular weight (Mn) of
PMMA-b-PAA was controlled from 10 kDa to 90 kDa. The binding capability of the block copolymer with
hydroxyapatite (HAP) was investigated by ultraviolet-visible spectroscopy (UV-Vis) and Fourier transform infrared (FTIR) spectroscopy. FTIR spectra confirmed that the
PMMA-b-PAA block copolymer could bind to HAP via bridging bidentate bonds. Both UV-Vis and FTIR spectra additionally indicated that a high
polymer concentration and low
solution pH favored the
polymer binding to HAP. The erosion-preventing efficacy of the
PMMA-b-PAA block copolymer in inhibiting HAP
mineral loss was quantitatively evaluated by atomic absorption spectroscopy (AAS). Based on the results,
polymer treatment reduced the amount of
calcium released by 27% to 30% in comparison with the unprotected samples. Scanning electron microscope (SEM) observations indicated that
PMMA-b-PAA
polymer treatment protected enamel from
acid erosion. This new amphiphilic block copolymer has significant potential to be integrated into
dentifrices or mouthrinses as an alternative non-
fluoride ingredient to reduce
tooth erosion.