Difunctional monomers of the formula, ##EQU1## where R is an organic linking group derived from a diol or a dihalide of the formula X-R-X, where X is either chlorine, bromine, iodine, or hydroxy, are prepared by reacting a conjugated diene, exemplified by anthracene, with an ester of 2-cyanoacrylic acid to form the Diels-Alder adduct of the ester. The ester adduct is hydrolyzed to ultimately obtain either the Diels-Alder adduct of either 2-cyanoacrylic acid--alkali metal salt or 2-cyanoacryloyl halide. These latter intermediates are respectively reacted with either the dihalide or the diol to afford the bis-Diels-Alder adduct of the R substituted bis (2-cyanoacrylate) monomer. The protective diene group may then be removed, for example, by reaction with excess maleic anhydride and the resulting difunctional monomer isolated. The difunctional monomers thus prepared can be utilized as crosslinking agents in blends comprising one or more of these difunctional monomers and at least one monofunctional monomer, exemplified by an ester of 2-cyanoacrylic acid. Alternately, one or more difunctional monomers can be homopolymerized or copolymerized to a highly crosslinked polymer. The copolymerized compositions of the monomer blends are particularly useful as adhesives, especially in dental applications for coating or sealing enamel surfaces of teeth to allay decay, or for the bonding of brackets to teeth in orthodontics the bond being substantially more resistant to moisture than where the monofunctional monomer is used alone.
根据上述描述,通过将共轭二
烯与
2-氰基丙烯酸酯反应形成
酯的Diels-Alder加合物来制备公式为##EQU1##的二官能单体,其中R是从二醇或二卤代物X-R-X的有机连接基衍生出的,其中X是
氯、
溴、
碘或羟基。
酯加合物经
水解最终得到
2-氰基丙烯酸-碱
金属盐或2-
氰基
丙烯酰卤的Diels-Alder加合物。这些后续
中间体分别与二卤代物或二醇反应,得到R取代的双Diels-Alder加合物(
2-氰基丙烯酸酯)单体。然后,保护性二
烯基团可以被去除,例如,通过与过量
马来酸酐反应,并分离得到所得的二官能单体。因此制备的二官能单体可以用作
交联剂,用于包含其中一个或多个这些二官能单体和至少一个单官能单体(例如
2-氰基丙烯酸酯)的混合物中。另外,一个或多个二官能单体可以被均聚或共聚成高度交联的
聚合物。单体混合物的共聚物组合在胶粘剂中特别有用,尤其是在牙科应用中,用于包覆或封闭牙齿表面的珐琅,以减轻腐蚀,或用于将托槽粘接到牙齿上,其中所使用的粘合剂对
水分的抵抗性明显更高,比仅使用单官能单体时更高。