Polymerization of cyclic monomers. VII. Synthesis and radical polymerization of 1,3-bis[(1-alkoxycarbonyl-2-vinylcyclopropane-1-yl)carboxy]benzenes

Fischer

et al. 2017

Macro Materials & Eng

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are made up of an organic matrix and silanized inorganic fillers. The organic matrix typically contains a mixture of different dimethacrylates and additives (photoinitiator system, stabilizer, etc.). Polymerization shrinkage is one of the main drawbacks associated with the use of dental composites. [3] The resulting shrinkage stress generated during the curing of the material may result in marginal leakage between the restoration and the tooth. As a consequence, marginal staining, postoperative sensitivity, or the formation of secondary caries can arise.2,2-Bis[4-(2-hydroxy-3-methacryloyloxypropoxy)phenyl]propane (bis-GMA) and bis-[(2-methacryloyloxyethoxy-carbonyl)-amino]-2,2,4-trimethylhexane (UDMA) are the most frequently used crosslinking monomers in dental composites. These monomers are highly reactive in free-radical polymerization, exhibit a relatively low polymerization shrinkage, and enable the formation of polymer networks with excellent mechanical Polymerization shrinkage of dental composites remains a major concern. Free-radically polymerizable cyclic monomers can be a conceivable alternative to methacrylates for the development of low-shrinkage composites. In this study, the one-step synthesis of the novel low viscosity difunctional vinylcyclopropanes 1-4 is described. Photopolymerization kinetics of these monomers are investigated by photo-differential scanning calorimeter, using bis(4methoxybenzoyl)diethylgermane as photoinitiator. Real-time near-infrared photorheology measurements are performed to evaluate rheological behavior (i.e., time of gelation, polymerization-induced shrinkage force) and chemical conversion (i.e., double bond conversion at the gel point, final double bond conversion) of the vinylcyclopropanes in situ. The potential of these monomers as reactive diluents in dental restorative materials is evaluated. Composites based on vinycyclopropanes 1-4 show good mechanical properties and exhibit significantly lower volumetric shrinkage and shrinkage stress than corresponding dimethacrylate-based materials. The results indicate that such monomers are promising candidates for the replacement of commonly used low viscosity dimethacrylates such as triethylene glycol dimethacrylate in dental composites.

Section: Methodsmentioning

confidence: 99%

“…In order to develop low‐shrinkage composites, several monofunctional and difunctional VCPs were synthesized and evaluated by our group . Unfortunately, dental composites solely based on VCPs could not be successfully developed due to an insufficient double‐bond conversion after irradiation.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Difunctional Vinylcyclopropanes as Reactive Diluents for the Development of Low‐Shrinkage Composites

Fischer

et al. 2017

Macro Materials & Eng

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“…Dichloromethane (DCM) was dried over molecular sieves. 1‐Ethoxycarbonyl‐2‐vinylcyclopropanecarboxylic acid and 2,2‐bis‐[4‐(2‐(2‐hydroxyethoxy)ethoxy)phenyl]propane 5 were prepared according to a procedure described in the literature. 4,8‐Bis(hydroxymethyl)tricyclo[5.2.1.0 2,6 ]decane and 2,2‐bis‐[4‐(2‐hydroxypropoxy)phenyl]propane were purchased from C. H. Erbslöh (Germany) and TCI (Germany), respectively.…”

Section: Methodsmentioning

confidence: 99%

Development of low‐shrinkage composites based on novel crosslinking vinylcyclopropanes

Tauscher

J of Applied Polymer Sci

et al. 2017

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Polymerization shrinkage of methacrylate-based dental composites remains a major concern in restorative dentistry. Cyclic monomers that undergo ring-opening polymerization are known to exhibit reduced polymerization shrinkage compared to methacrylates. In this article, the synthesis of four crosslinking 1,1-disubstituted 2-vinylcyclopropanes bearing rigid spacers is described. These monomers were synthesized by esterification of 1-ethoxycarbonyl-2-vinylcyclopropane-1-carboxylic acid with the corresponding diols. The photopolymerization kinetics of these monomers was investigated by photo-differential scanning calorimeter using bis(4-methoxybenzoyl)diethylgermane as the photoinitiator. The synthesized vinylcyclopropanes (VCPs) were shown to be more reactive than the frequently used reactive diluent triethylene glycol dimethacrylate. Composites based on these VCPs showed good mechanical properties and exhibited a significantly reduced volumetric shrinkage and shrinkage stress compared to a corresponding dimethacrylatebased restorative material. This work highlights the excellent potential of VCPs as alternatives to methacrylates in the development of low-shrinkage dental composites.

“…DCM was dried over molecular sieves. 1‐Ethoxycarbonyl‐2‐vinylcyclopropane‐1‐carboxylic acid, 1,8‐bis[(1‐ethoxycarbonyl‐2‐vinylcyclopropan‐1‐yl)carbonyloxy]‐3‐6‐dioxaoctane ( 9 ) and VCP 10 were prepared according to procedures described in the literature. BMDG was purchased from Synthon Chemicals GmbH (Germany).…”

Section: Methodsmentioning

confidence: 99%

Synthesis of acidic vinylcyclopropanes for dental applications

Fischer

et al. 2017

Polymer International

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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