Degree Type

Thesis

Date of Award

2013

Degree Name

Master of Science

Department

Mechanical Engineering

First Advisor

Reza Montazami

Abstract

The important role of the nanostructure of conductive network composite (CNC) layers on the performance of ionic polymer-metal composite (IPMC) transducer has been discussed detailedly. IPMC transducers exhibit both electromechanical and mechanoelectrical behaviors. When subjected to an external electric field, electromechanical behavior of IPMC transducers causes an actuation response which can be reversed by alternation of the polarity of the applied field. The same structure, when subjected to an external mechanical force, generates an electrical signal which can be picked up by ordinary electronic. Mechanoelectrical behavior of IPMCs is utilized in stress sensors and structural health monitoring devices. We have employed the layer by layer (LbL) self-assembly technique to fabricate CNC layers based on spherical gold nanoparticles (AuNPs) and poly(allylamine hydrochloride) (PAH) polycation with a controllable thickness in nano and micro ranges; which, when compared with IPMC transducer without CNC layers on both sides of ionomeric membrane, show an improvement in the actuation and sensing performances significantly. Moreover, the thickness and conformation of CNC nanostructure can also be adjusted by the addition of small salt molecules. The presence of salt ions can affect the conformation of polymer chains and their molecular shape since it screens the repulsive force among the same charges on the repeat units of polyelectrolyte. As a result, the polymer chains become more coiling when dissolved in an environment with high ionic strength. At the same time, while part of the charges have been screened, larger amount of polymer chains or nanoparticles are required to reverse the surface charge led by the previous layer. The presence of salt ions in CNC can also prohibit the aggregation of AuNPs and promote a more homogeneous distribution of the nanoparticles. In this case, both the thickness and conformation of CNC have been changed; which, as indicated by experimental results, has a positive influence on the actuation and sensing performance of IPMC devices.

Copyright Owner

Wangyujue Hong

Language

en

File Format

application/pdf

File Size

73 pages

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