Yohann Catel

Monomers for adhesive polymers, 13.1 Synthesis, radical photopolymerization and adhesive properties of polymerizable 2-substituted 1,3-propylidenediphosphonic acids

A family of polymerizable 2-substituted-1,3-propylidenediphosphonic acids was successfully synthesized for an application in dental adhesives. Methacrylates as well as N-alkyl-acrylamides were prepared. Those monomers were synthesized in 4 to 6 steps and were fully characterized by 1H NMR, 13C NMR, 31P NMR spectroscopy and by HRMS. In order to evaluate their reactivity, the copolymerization of each monomer with N,N′-diethyl-1,3-bis-(acrylamido)propane (DEBAAP) in DMF was investigated by photo-DSC. Bis-(4-methoxybenzoyl)diethylgermanium (BMDG) was added as the photoinitiator to each mixture of acidic monomer/DEBAAP/DMF (2/3/5: mol/mol/mol). It was demonstrated that each monomer efficiently copolymerized with DEBAAP. Self-etching enamel-dentin adhesives containing these new diphosphonic acids were formulated and used to mediate a bond between the dental hard tissues (dentin and enamel) and a restorative material. According to both dentin and enamel shear bond strength measurements, 2-methacryloyloxymethyl-1,3-propylidenediphosphonic acid 8, 2-[N-(2-methacryloyloxyethyl)-carbamoyloxymethyl]-1,3-propylidenediphosphonic acid 10a and 2-[N-(10-methacryloyloxydecyl)-carbamoyloxymethyl]-1,3-propylidenediphosphonic acid 10b were the best candidates to enter new formulations. Those diphosphonic acids were significantly more efficient regarding the etching of enamel than the 1,3-bis(methacrylamido)propane-2-yl dihydrogen phosphate 17, a monomer already used in some commercially available dental formulations.

Monomers for adhesive polymers, 17.a Synthesis, photopolymerization and adhesive properties of polymerizable phosphonic acids bearing urea groups

Abstract Four polymerizable phosphonic acids bearing urea groups 4a, 4b, 9a, and 9b as well as the 10-(methacryloyloxy)decylphosphonic acid 10 were synthesized in four to six steps. They were characterized by 1H, 13C, and 31P NMR spectroscopy and by high-resolution mass spectroscopy. Contrary to methacrylates 4a and 4b, methacrylamides 9a and 9b were hydrolytically stable in deuterated water/deuterated ethanol solutions. The photopolymerization behavior of acidic monomers 4a, 4b, 9a, 9b, and 10 and their corresponding phosphonates were studied using a differential scanning calorimeter. Homopolymerizations and copolymerizations with N-butyl-N-ethylacrylamide were carried out. The presence of a urea group was found to significantly increase the rate of polymerization. Monomers bearing a phosphonic acid group were more reactive than their corresponding phosphonates. Self-etch adhesives based on monomers 4a, 4b, 9a, and 9b were able to provide a strong bond between a composite and the dental hard tissues (dentin and enamel). The presence of a urea group led to a significant increase in the shear bond strength to both dentin and enamel.

Evaluation of alternative monomers to HEMA for dental applications

OBJECTIVE The objective of this work is to find potential alternative monomers to 2-hydroxyethyl methacrylate (HEMA) for dental materials (self-etch adhesives and luting composites). METHODS Monomers 1-9 were tested as potential HEMA substitutes. Methacrylates 4, 5 and 6 and (N-methyl)acrylamides 7-9 were synthesized and characterized by 1H NMR spectroscopy. The reactivity of each monomer was studied using photo-DSC. Mixtures of monomers 1-9 with the urethane dimethacrylate UDMA (1/1: wt/wt) were formulated and cured. The water sorption and solubility of these materials were determined according to ISO 4049. Luting composites based on monomers 1-9 or on HEMA were formulated. The flexural strength and modulus of elasticity were measured using a three-point bending setup, according to ISO 4049. Self-etch adhesives containing monomers 1-9 or HEMA were prepared and used to mediate a bond between the dental composite Tetric EvoCeram® and both dentin and enamel. The shear bond strength (SBS) was measured using a Zwick universal testing machine. RESULTS Polymerizable diols 3 and 4 as well as (N-methyl)acrylamides 7-9 were found to be significantly more reactive than HEMA. Resins based on the hydrophilic monomers 3, 7 and 8 exhibited a significantly higher water sorption than the corresponding HEMA-containing material. Luting composites containing monomers 2, 3, 6 and 7 showed similar or even improved mechanical properties compared to the reference material containing HEMA. Self-etch adhesives containing monomers 4 and 9 provided significantly higher dentin SBS than the reference material. SIGNIFICANCE Some of the evaluated monomers are promising candidates for the development of HEMA-free dental materials.

Monomers for adhesive polymers, 18. Synthesis, photopolymerization and adhesive properties of polymerizable α-phosphonooxy phosphonic acids

Abstract Four polymerizable α-phosphonooxy phosphonic acids 7a, 7b, 9 and 16 were synthesized in seven steps. They were characterized by 1H, 13C and 31P NMR spectroscopy and by high-resolution mass spectroscopy. The copolymerization of acidic monomers 7a, 7b, 9 and 16 with 2-hydroxyethyl methacrylate was studied using a differential scanning calorimeter. Due to the presence of two acidic groups, those monomers are significantly more reactive than 10-methacryloyloxydecylphosphonic acid (MDPA) and 10-methacryloyloxydecyl dihydrogen phosphate (MDP). Self-etch adhesives based on monomers 7a, 7b, 9 and 16 were formulated and used to mediate a bond between a dental composite and the dental hard tissues (dentin and enamel). These adhesives exhibit excellent performances and provide significantly higher dentin and enamel shear bond strength than adhesives based on MDP or MDPA.

Determination of homopolymerization kinetics and copolymerization with methyl methacrylate of diethyl 9-(methacryloyloxy)-2-oxo-nonylphosphonate, 9-(methacryloyloxy)-2-oxo-nonylphosphonic acid and diethyl 9-(methacryloyloxy)-nonylphosphonate

Abstract The three polymerizable monomers diethyl 9-(methacryloyloxy)-2-oxo-nonylphosphonate M1, 9-(methacryloyloxy)-2-oxo-nonylphosphonic acid M2 and diethyl 9-(methacryloyloxy)-nonylphosphonate M3 are examined for their free radical polymerization and copolymerization activity in methanol between 40 and 65°C. Polymerization proceeds readily through a thermal free radical initiation. The intensity exponents for the monomer and initiator are only slightly over 1 and approximately 0.5, respectively. This is in accordance with the results typically observed for an ideal free radical polymerization with bimolecular termination. The kinetics of copolymerization with methyl methacrylate (MMA) are monitored by online 1H nuclear magnetic resonance (NMR) spectroscopy. Two copolymerization reactions for each pair of co-monomers are sufficient to evaluate the kinetic data using the Jaacks method, the Fineman-Ross method and the nonlinear least squares method. All three methods give similar results for particular monomer/MMA couples.

CHAPTER 8:Phosphorus-Based Monomers Used for Dental Application

The currently used enamel/dentin adhesives are based on a mixture of crosslinking and monofunctional monomers and further additives such as solvents, photoinitiators, fillers, etc. The acidic monomer is a key component of the self-etching adhesives as it is responsible for the simultaneous demineralization and infiltration of the dental hard tissues. Among the acidic monomers, polymerizable phosphonic acids (PAs) and dihydrogen phosphates (DHPs) have attracted much attention. The efficiency of the adhesive is directly related to the structure of the included monomers. In this context, several PAs and DHPs were synthesized in order to improve parameters such as the shear bond strength to dentin and enamel, the stability of the adhesive formulation, the chemical adhesion to the tooth tissues, etc. Some of these monomers are nowadays included in commercial dental adhesives.