Martins P, Costa C M, Benelmekki M, Lanceros-Mendez S
Centro/Departamento de Física da Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
J Nanosci Nanotechnol. 2012 Aug;12(8):6845-9. doi: 10.1166/jnn.2012.4543.
Ni0.5Zn0.5FeO4 ferrite/polyvinylidene fluoride composite films were prepared by a solution method and melt processing. As nanoparticle dispersion and polymer electroactive phase content are some of the key factors for improving magnetoelectric coupling in the composites, the dispersion of ferrite nanoparticles in the polymeric matrix was studied by preparing samples by two alternative dispersion routes: ultrasound and citric acid nanoparticle surfactation. The nucleation of the electroactive beta-phase of the polymer was observed in composites produced by nanoparticle dispersion by ultrasound. This fact avoids the need of stretching composites at elevated temperature in order to obtain the electroactive phase and obtain magnetoelectric composites. By this method, nevertheless, large nanoparticle agglomerates are obtained. Nanoparticle dispersion is largely improved by citric acid surfactation of the nanoparticles. On the other hand, the beta-phase of the polymer is not nucleated due to the modification of the nanoparticle-polymer interaction due to the presence of the surfactant.
通过溶液法和熔融加工制备了Ni0.5Zn0.5FeO4铁氧体/聚偏二氟乙烯复合薄膜。由于纳米颗粒分散和聚合物电活性相含量是改善复合材料中磁电耦合的一些关键因素，通过两种替代分散途径制备样品来研究铁氧体纳米颗粒在聚合物基体中的分散情况：超声和柠檬酸纳米颗粒表面活性剂法。在通过超声进行纳米颗粒分散制备的复合材料中观察到了聚合物电活性β相的成核。这一事实避免了在高温下拉伸复合材料以获得电活性相并制备磁电复合材料的需要。然而，通过这种方法会得到大的纳米颗粒团聚体。通过纳米颗粒的柠檬酸表面活性剂法，纳米颗粒的分散性得到了很大改善。另一方面，由于表面活性剂的存在改变了纳米颗粒与聚合物之间的相互作用，聚合物的β相没有成核。
