| Electroactive polymers (EAPs) are widely used in many areas, such as actuators, sensors and transducers. This research focused on developing new electroactive polymer systems and exploiting applications of EAPs in biosensors. Research objectives were: (1) studying the recrystallization of irradiated P(VDF-TrFE) copolymer to deepen our understanding of EAPs; (2) developing a series of novel high performance and inexpensive EAP systems---P(VDF-TrFE)-based copolymer blends; and (3) exploring new EAP in biosensor applications.; The structure and morphology of recrystallized P(VDF-TrFE) with 65/35 mol% copolymer samples that had previously been irradiated were studied using X-ray, FTIR and DSC techniques. The crystalline structure and morphology, as well as the conformation of the polymer chains, were determined by X-ray and FTIR. Their thermal behaviors, including phase transition, were characterized by DSC. It was found that in samples irradiated with doses of less than 60 Mrad, the recrystallized copolymers exhibited similar behaviors to unirradiated samples except for having a lower level of crystallinity. However, for samples irradiated with higher doses, such as 60, 85 and 100 Mrad, the X-ray diffraction results indicated that the crystalline structure of the recrystallized copolymers were completely different than unirradiated samples. A systematic study of the crystalline structure and phase transition behavior of these recrystallized P(VDF-TrFE) 65/35 mol% samples is reported here.; In order to create inexpensive EAPs, a blending between P(VDF-TrFE) and P(VDF-CTFE) copolymers was developed, both of which are commercially available in their semi-crystalline form is reported. First, the composition effects on miscibility, crystalline structure, and phase transition behavior were evaluated with DSC, X-ray and hysteresis loop measurements. The experimental results showed that stretching the polymer before annealing increases the polarization response. This improved treatment made the VDF segments of both copolymers in the blend co-crystallize and generate rich TrFE and CTFE regions. These regions served as boundary layers located near the VDF crystalline regions. The ordering degree of these boundary layers may be changed by an electric field, which results in a high polarization response.; Finally, the feasibility study of microelectronic mechanical diaphragm (MEMD) using polymers is presented. First, diaphragms with diameters in the mm scale and thickness in the mum scale were fabricated using conventional methods. Their resonance frequencies and quality merit factors (Q value) in liquid were then demonstrated. The Q values in liquid medium were found to be the same or better than that measured in air. A microfabrication process flow chart based on current silicon technology has been designed and established. While using the current microelectronic fabrication processes, which are stressful to many materials, the polymer film showed great resilience and remained unchanged, flat and affixed to the Si wafer. (Abstract shortened by UMI.)... |
