Shpotyuk Olha, Ingram Adam, Shpotyuk Oleh
Danylo Halytsky Lviv National Medical University, 69, Pekarska str., Lviv, 79010, Ukraine.
Opole University of Technology, 75, Ozimska str., 45370, Opole, Poland.
Nanoscale Res Lett. 2016 Dec;11(1):528. doi: 10.1186/s11671-016-1751-8. Epub 2016 Nov 28.
Positron annihilation spectroscopy in lifetime measuring mode exploring conventional fast-fast coincidence ORTEC system is employed to characterize free volume structure of commercially available acrylic-type dental restorative composite Charisma® (Heraeus Kulzer GmbH, Germany). The measured lifetime spectra for uncured and light-cured composites are reconstructed from unconstrained x3-term fitting and semi-empirical model exploring x3-x2-coupling decomposition algorithm. The governing channel of positron annihilation in the composites studied is ascribed to mixed positron-Ps trapping, where Ps decaying in the third component is caused entirely by input from free-volume holes in polymer matrix, while the second component is defined by free positron trapping in interfacial free-volume holes between filler nanoparticles and surrounded polymer matrix. Microstructure scenario of the photopolymerization shrinkage includes cross-linking of structural chains in polymer matrix followed by conversion of bound positron-electron (positronium) traps in positron-trapping interfacial free-volume voids in a vicinity of agglomerated filler nanoparticles.
采用正电子湮没光谱的寿命测量模式，利用传统的快-快符合ORTEC系统来表征市售丙烯酸类牙科修复复合材料Charisma®（德国贺利氏古莎有限公司）的自由体积结构。未固化和光固化复合材料的测量寿命谱通过无约束x3项拟合和探索x3-x2耦合分解算法的半经验模型进行重建。所研究复合材料中正电子湮没的主要通道归因于正电子-正电子素的混合捕获，其中在第三成分中衰变的正电子素完全由聚合物基体中自由体积空穴的贡献引起，而第二成分由填充纳米颗粒与周围聚合物基体之间界面自由体积空穴中的自由正电子捕获定义。光聚合收缩的微观结构情况包括聚合物基体中结构链的交联，随后是聚集的填充纳米颗粒附近正电子捕获界面自由体积空隙中束缚的正电子-电子（正电子素）陷阱的转变。
