Thebehaviorofwater-solublephotoinitiatorswithcrownethersindentaladhesivesisunknown.Thisstudyinvestigatedthe effectofsodiumacylphosphineoxide(APO-Na)withcrownetherinahydrophobicadhesiveonadhesiontoteeth.Sodium 2,4,6-trimethylbenzoyl-phenylphosphine oxide (TMPO-Na = APO-Na) was synthesized in 67.1% yield and identified by 1 H NMR. APO-Na was dissolved in hydrophobic resins in the presence of a crown ether (ionophore effect). Thirty kinds of experimentalsingle-stepadhesivescomprisingAPO-Na,CE,Bis-GMA,6-methacryloyloxyhexylphosphonoacetate(6-MHPA), and4-methacryloyloxyethyltrimelliticacid(4-MET)weretherebyprepared.Shearbondstrengthtounetchedgroundteeth wasmeasuredatacrossheadspeedof1.0mm/min,andthedatawereanalyzedbyANOVA.Theshearbondstrengthresults of bonding resins containing APO-Na with 18-crown-6-ether (CE-6) were significantly higher than that without CE-6 (control) (p<0.05).Higherbondstrengthvalues[forenamel:BR24at19.3(3.2)MPa;fordentin:BR29at20.2(4.7)MPa]wereachieved with the adhesives containing APO-Na, CE-6, 6-MHPA, and 4-MET. Therefore, it was found that APO-Na with CE-6 contributed to the efficient bonding performance of single-step adhesive to teeth. However, in view of the biosafety hazard posedbycrownethers,thesearchisstillonforreagentsthatarebiologicallysaferthancrownethers-butwithionophor effects-tobeusedindentaladhesives.
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.
It was tried to microencapsulate erythritol as a phase change material with the interfacial polycondensation reaction method by using the (W/O) emulsion and to characterize the microcapsules prepared. In the experiment, toluene diisocyanate, diphenyl methane diisocyanate and hexamethylenediisocyanate were used to form the polyurethane shell and the effects of them on the heat storage density and the microencapsulation efficiency were investigated. Furthermore, the effect of supercooling prevention agent on the phase change behavior of erythritol was investigated. The microcapsules prepared with toluendiisocyanate monomer showed the highest heat storage density and the higher microencapsulation efficiency. Considerable supercooling phenomenon in the microcapsule was observed and prevented to a certain degree by addition of potassium dihydrogen phosphate and calcium sulfate as the supercooling prevention agent.
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