Preparation of Bis-GMA monomer which does not release bisphenol A

本研究的目的是通过去除双酚A （BPA）来证实双酚A - gma单体的安全性，同时考察BPA清除自由基的能力。与聚甲基丙烯酸甲酯（PMMA）的自由基清除反应PMMA中的自由基残留量与其玻璃化温度有关，并可通过加热调节。制备了甲基丙烯酸酯单体与MMA共聚物，以提高聚合物在Bis-GMA中的溶解度。这些共聚物的自由基清除反应不能完全去除BPA。考虑到自由基前驱体在Bis-GMA中的溶解度，采用了低分子量自由基前驱体，可见光和热聚合引发体系。热自由基形成体系不能成功地去除BPA，导致Bis-GMA的热聚合。另一方面，可见光辐照自由基形成体系通过调节自由基前驱体的浓度和光照强度来控制自由基清除反应和聚合反应。色谱法去除双酚a采用硅胶柱层析法对商品双酚a - gma进行纯化，考察纯双酚a - gma的化学活性。在纯Bis-GMA中加入自由基前体、共聚物前体或引发剂均不会产生BPA，这表明含有Bis-GMA的牙科产品在去除BPA后不会产生BPA释放等有害影响。在纯化双酚a的过程中，还发现吸附剂可以去除双酚a。

The aim of the present investigation was to confirm the safety of Bis-GMA monomer by removing bisphenol A (BPA) from the monomer paying attention of the radical scavenging ability of BPA.1.Radical scavenging reaction with poly(methyl methacrylate) (PMMA)The amount of radical remaining in PMMA was related to its glass transition temperature and the amount was adjustable with heating. Copolymers of methacrylate monomer with MMA was prepared to enhance the solubility of polymers in Bis-GMA. The radical scavenging reaction with these copolymers could not remove BPA completely.2.Radical scavenging reaction with precursor of radicalTaking into account the solubility in Bis-GMA, low molecular weight precursors of radical, initiator system of visible light and heat polymerization, were used. Radical forming system by heat was not able to remove BPA successfully resulting in the heat polymerization of Bis-GMA. On the other hand, radical forming system by visible light irradiation was able to control both radical scavenging reaction and polymerization by adjusting the concentration of precursor of radical and the intensity of light irradiation.3.Removal of BPA by chromatographyThe main monomer component of Bis-GMA was purified by silica gel column chromatography treatment of commercial Bis-GMA product to examine the chemical reactivity of pure Bis-GMA. The addition of a precursor of radical, copolymer or initiator into pure Bis-GMA did not produce BPA, which indicated that dental products containing Bis-GMA never exert a harmful effect such as release of BPA once BPA was removed. It was also suggested in the process of the purification of Bis-GMA that BPA can be removed by adsorbents.