Pfeifer Carmem S, Wilson Nicholas D, Shelton Zachary R, Stansbury Jeffrey W
Craniofacial Biology Department, University of Colorado.
Polymer (Guildf). 2011 Jul 7;52(15):3295-3303. doi: 10.1016/j.polymer.2011.05.034.
Chain-transfer reactions from thiols to methacrylates are expected to delay gelation and possibly reduce stress at the bonded interface of dental restorations. Thiol additives with varying structures were combined with a dimethacrylate commonly used in dental materials. Polymerization stress/modulus development were monitored by a tensometer/rheometer, respectively, both coupled with RT-NIR. For all thiol-modified materials, conversion and modulus were 5-25 % higher than the control, and maximum reaction rate was 25-50 % lower. Gel point conversions were 12-22 % (control=5 %), and deceleration was observed at later stages in conversion (30-60 %; control=15 %). Consequently, even with increased conversion/modulus, stress values were either equal or reduced compared to the control. This approach does not require any modification in the bonding/photoactivation procedures, and seems promising for stress management not only in polymeric dental materials, but also for other applications of glassy, crosslinked photopolymers, as long as thiol volatility is addressed.
预计硫醇与甲基丙烯酸酯之间的链转移反应会延迟凝胶化，并可能降低牙科修复体粘结界面处的应力。将具有不同结构的硫醇添加剂与牙科材料中常用的二甲基丙烯酸酯混合。分别通过张力计/流变仪监测聚合应力/模量的发展，二者均与实时近红外光谱仪联用。对于所有硫醇改性材料，转化率和模量比对照组高5%-25%，最大反应速率低25%-50%。凝胶点转化率为12%-22%（对照组为5%），在转化率后期（30%-60%；对照组为15%）观察到减速现象。因此，即使转化率/模量增加，与对照组相比，应力值要么相等，要么降低。这种方法不需要对粘结/光活化程序进行任何修改，而且对于应力管理似乎很有前景，不仅适用于聚合牙科材料，也适用于玻璃态交联光聚合物的其他应用，只要解决硫醇挥发性问题即可。
