Stimuli Sensitive Behaviour of Modified Polyacrylonitrile Fibres Available to Purchase

Polymeric fibres that have a unique capability to change their structure in response to small environmental changes such as pH, electrolyte and electric field are an attractive alternative for artificial muscles. Stimuli sensitive fibres were prepared by the modification of commercial polyacrylonitrile (PAN) fibres. The modification was carried out in two steps: thermo-oxidation and hydrolysis. During the thermo-oxidation step, the crosslinks imparted through the pendant nitrile groups provided a stable structure. While in the subsequent saponification step, the uncrosslinked nitrile groups were converted to responsive carboxylic acid groups. The effect of stabilization parameters and saponification conditions on the structure, properties and swelling behaviour of these fibres was investigated. The fibres showed muscle like expanding and contracting behaviour stimulated by changes in pH of the environment.