Precision Synthesis of a Long-Chain Silane Coupling Agent Using Micro Flow Reactors and Its Application in Dentistry

Abstract

In dentistry, a wide range of materials is available for restorative treatment; a typical product of such restorative materials mainly consists of radically polymerizable monomer(s) and inorganic filler(s) (for added physical strength), as well as a surface modifier (e.g. silane coupling agent) for improved affinity between monomer and filler. It is favorable to use an optimal surface modifier depending on the respective restorative materials. However, commercially available surface modifiers, which are synthesized by the ton, are not always suited for what is required for properties of the many different dental restorative materials. As a potential solution to such a problem, we focused on the latest technology, "micro flow reactors" that enabled an on-demand low-volume synthesis of many types of surface modifiers. Using micro reaction fields of such flow reactors, we synthesized a novel long-chain silane coupling agent. Compared to the control system synthesized using a conventional reaction flask, the novel system enabled significant reduction in reaction time without inducing any major side reactions. A dental composite resin that was treated with the novel coupling agent exhibited higher toughness, suggesting that such a silane coupling agent was an effective surface modifier.

Effect of Long-Chain Silane on Mechanical Properties of Experimental Resin Composites

“…The nding reiterates that of an earlier study performed on silanes with a 10-carbon hydrocarbon chain which was able to better resist hydrolytic degradation than MPS [18]. Another study found that by virtue of a long hydrocarbon chain length, experimental resin composites synthesised with MOS exhibit lower viscosity while having higher exural modulus and strength and being less brittle than MPS [21]. This may be explained by the 'restrained layer theory', whereby silanes between the inorganic substrate and resin polymer matrix are capable of deformation and act as a stress breaker [22].…”

“…Three-point bending test is widely used for assessing denture base materials and resin composites [21,23,25,26]. Our current study samples have demonstrated mechanical properties with values at the same magnitude compared with an earlier study of a similar setup [21].…”

“…This may be explained by the 'restrained layer theory', whereby silanes between the inorganic substrate and resin polymer matrix are capable of deformation and act as a stress breaker [22]. However, in that study, such differences were not statistically signi cant [21].…”

Surface Conditioning and Silanization for Ceramic Adhesion

“…Researches on other surface treatments is in progress in an attempt to improve adhesion and its durability in the oral cavity. (2)…”

“…Phosphate esters can bond straight to non-silicabased ceramics such as zirconia. It has been stated that using this phosphate ester one can enhance the hydrolytic Figure 2: Silane coupling agents (2)…”