Bismethacrylate-Based Hybrid Monomers via Michael-Addition Reactions

Abstract

Bismethacrylate monomers and macromonomers bearing various alkoxysilyl units were prepared by convenient Michael addition of ethylene glycol acrylate methacrylate (EGAMA) and ethylene glycol bisacrylate (EGBA) to various α,ω-alkoxysilylamines. The resulting monomers and macromonomers have been characterized in detail by NMR spectroscopy, VPO measurements and FAB−MS. Average molecular weights M n ranged between 530 and 1600 (VPO) in addition reactions with bisacrylates. FAB−MS evidenced the formation of a homologous macromonomer series. Viscosities of the liquid monomers are relatively low, ranging from 52 to 305 mPa·s. This renders these compounds interesting as reactive diluents in dental composite formulations. Polymerization of the monomers and macromonomers resulted in low volumetric shrinkage in the range of ΔV = 2.2−7.8% at high methacrylate conversion. Cross-linking was monitored by photo-DSC. Furthermore, composites were prepared by mixing Bis-GMA with the new hybrid monomers, initiator and glass filler. The composites showed compressive strengths of 190−329 MPa, flexural strengths from 23 to 53 MPa and Young's moduli between 2090 and 5060 MPa. Low volumetric shrinkage was observed also for the composites upon photopolymerization, ranging from only 0.8% to 2.2% in comparison to over 3% shrinkage of commercially available composites. Besides the viscosity reducing effect due to the branched structure, the pendant alkoxysilyl groups of the synthesized hybrid monomers can be polymerized to form nanoparticles with reactive acrylate surface, permitting the in situ preparation of nanocomposites.

Understanding the regioselectivity of Michael addition reactions to asymmetric divinylic compounds

“…1), have been used to obtain novel methacrylates by profiting from the different selectivities of both amine and mercapto groups in Michael addition. 1,3 Our group has recently extended this synthetic strategy to the molecular system acrylamide/methacrylate (AAEMA, structure shown in Fig. 1).…”

“…Since the pioneering work of Mülhaupt et al 1 on the selective Michael addition of diamines to the acrylate group of ethyleneglycol diacrylate methacrylate for the preparation of dimethacrylates, some other examples can be found in the recent literature that use this selectivity towards different acrylic groups in asymmetric divinylic compounds to obtain novel methacrylates. Thus, this synthetic strategy has allowed for the easy preparation of polymethacrylates bearing pendant special groups such as phosphonate, 2,3 hydroxyl, 4 stearyl, 5 or prodendronic amine moieties.…”

Sol-Gel Materials, 1. Synthesis and Hydrolytic Condensation of New Cross-Linking Alkoxysilane Methacrylates and Light-Curing Composites Based upon the Condensates

“…The advantage of this route is that compounds with a defined number of both polymerisable methacrylic and hydrolysable trialkoxysilyl groups can be obtained. Recently, the synthesis of silane 1 was also described by Mülhaupt et al [20] It is known, [21,22] that a number of mono-or difunctional (meth)acrylamidoorganosilicon compounds were synthesised by the reaction of the corresponding aminoorganosilicon compounds with (meth)acryloyl chloride. In contrast to these silanes, in silane 4 and 5 two methacrylate functions are connected with the propyltriethoxysilyl moiety via an amide group.…”

Acrylate-Terminated Macromonomers by Michael Addition

“…[5] Recently we reported on methacrylate-terminated monomers and macromonomers, prepared by the addition of alkoxysilane amines to 2-acryloyloxyethyl acrylate (1,2-ethylene glycol diacrylate, EGDA) and 2-methacryloyloxyethyl acrylate. [6,7] Encouraged by the promising results, we proceeded to investigate acrylate-terminated monomers obtained by the Michael addition of aminopropyl methyl diethoxysilane to EGDA, p-phenylene diacrylate (PDA) and 1,4-cyclohexanediol diacrylate (CHDA). This paper focuses on the influence of the different acrylates and the chain length of the addition products on polymerization behavior, viscosity and mechanical properties of the respective composite materials.…”