| Electro-active is natural character of many biotic tissues and biotic macromolecule. Themolecules and tissues of which living things are made, protein DNA RNA bones skin bloodvessels are all natural bio-electrets. Bones are piezoelectric materials being investigated forlong time. Bioelectricity play important role in the remolding and shaping of bones. Electricalstimulation can accelerate the bone healing process. Electrical stimulation is widely used inclinical treatment of fracture and Nonunion. Research and clinical trials show that a negativevoltage applied for assembling negative charges accelerating the healing of fracture. Themethod includes implanting electrodes to give DC or AC, or the body in the electric fieldaccumulated charge into to promote healing. However, inconvenient clinical treatment,electrical stimulation is difficult to be stability and effective, and there should be some harmfor the organs in electric field. To solve the above problems, the subject developed abiodegradable0-3electric material, an electrical activity of functional material, consisting ofsuitable flexibility, dielectric and piezeolectiricity. implanted in the body as a hard tissuerepairing material without external power supply; the cumulative negative charges canpromote bone growth. As the new organization continues to build, material degradates.Degradation products can be absorbed by the body. Experiment with excellentbiocompatibility of poly-hydroxyl acid ester (PHA) family of materials PHBHHx as thematrix material, the barium titanate (BTO) as the inorganic phase. We prepared abiodegradable piezoelectric material, dielectric character and piezoelectric character weretested and, the degradation and biological mineralization were evaluated.First,0-3type BTO/PCL composites were fabricated by2-step-hot-pressing method,using micro and nano particle BTO as inorganic phase. Because of the uniting of the nanoparticles. They cannot disperse homogeneously in PCL. The impact strength decreased heavily.The adding of BTO raised the permittivity of PCL but not so much. There’s no piezoelectricityfound in the composites. So for homogenously dispersing of particles, micro particle used asinorganic phase and PHBHHx as the organic one.Then after purifying of PHBHHx (using1HNMR and DMA for the testing pureness) asystematic study of the dielectric relaxation spectroscopy(DRS) of biodegradablepoly(3-hydroxybutyrate-co-3-hydroxyhexanoate,PHBHHx) polyester, considering observingthe electric properties well and potential applications in bio-medical. The dielectricspectroscopy was measured over a wide frequency range (100～107Hz) from the temperature-100°C to60°C. The glass transition relaxation and sub-glass transition relaxation were observed by DRS in PHBHHx. In addition, a nearly constant loss (NCL) behavior was foundby analyzing of the dielectric and conductivity spectra.Finally, BTO/PHBHHx composites were fabricated using casting and hot-pressing. Itwas found that hot-pressing was the better method for prepareing. Dielectric andferroelectricity properties of polymeric composites were investigated. The dielectricspectroscopy of the composites was measured over a wide frequency range (100～107Hz)from the temperature-100°C to60°C. The composition dependent dielectric behavior wasmodeled by a self-consistent effective medium theory. A percolation threshold of0.367wasobserved in the composites. The glass transition relaxation of the composite is also discussedby comparing the popular V gel-Fulcher-Tammann law and a new glass model. In addition,the enhanced ferroelectricity and piezoelectricity reveals that the composites also are verypromising for bio and medical application. |
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