Synthesis of acidic vinylcyclopropanes for dental applications

Abstract

The multistep synthesis of four new acidic vinylcyclopropanes is described. These monomers were fully characterized using 1H NMR, 13C NMR and 31P NMR spectroscopy and high‐resolution mass spectrometry. The homopolymerization of the corresponding polymerizable di‐tert‐butyl phosphates as well as the copolymerization of each acidic monomer with 1,1‐diethoxycarbonyl‐2‐vinylcyclopropane were investigated using photo‐differential scanning calorimetry with bis(4‐methoxybenzoyl)diethylgermane as photoinitiator. Self‐etch adhesives based on the synthesized acidic vinylcyclopropanes are able to achieve a strong bond between a dental composite and both dentin and enamel. Flowable composites containing these acidic vinylcyclopropanes exhibit good mechanical properties. The replacement of methacrylates by vinylcyclopropanes leads to a significant reduction of the shrinkage stress of flowable composites. © 2017 Society of Chemical Industry

Overviews on the Progress of Flowable Dental Polymeric Composites: Their Composition, Polymerization Process, Flowability and Radiopacity Aspects

“…Certainly, bis(4-methoxybenzoyl)diethylgermanium is proposed as the proper photo-initiator in that case along with CQ/tertiary amine. Flowable composites containing these acidic vinylcyclopropanes proved promising alternatives, since the replacement of methacrylates by vinylcyclopropanes led to a significant reduction in the shrinkage stress for their case [ 14 ]. Other, less known acrylates may exist in commercial products, such as Filtek TM Supreme Ultra Flowable Restorative (3M ESPE, St. Paul, MN, USA), which is enhanced by 2,2-bis [4-(3-methacryloxypropoxy)phenyl]propane in its resin system [ 15 ].…”

Recent Advances in Germanium‐Based Photoinitiator Chemistry

“…Based on the synthetic approach presented in Equation 6 the first bisacylgermane was implemented as a commercially available photoinitiator [bis(4‐methoxybenzoyl)diethylgermane, Ivocerin ® ]. Ivocerin ® and related bisacylgermanes show significantly enhanced extinction coefficients compared to monoacylgermanes resulting in reduced curing times and increased curing depth of the final composite material . Beside of these benefits, Ivocerin ® still suffers from inefficient curing depths at wavelengths >450 nm .…”

Photoinduced ring-opening polymerizations

“…Catel et al also studied the effect of the size of the substituents on the monomer reactivity of acidic derived VCP (Fig. 16; compounds 2 and 3) [243]. Monomers with an amide group polymerized faster than those bearing an ester group (with LED and BMDG as PI), double bond conversion reaching 92 % in 45 s in the case of the VCP monomer with an ester group and n 4 while it reached 92 % in 20 s with VCP displaying an amide bond.…”