Patent ID: 8361368
Filing Date: 2013-01-29
Classification: C08F

Abstract:
1. A method of making a polymeric article having a plurality of shape memory configurations, the article being formed of a thermoplastic perfluorosulfonic acid ionomer polymer with a polytetrafluoroethylene molecular backbone and perfluoroether sulfonic acid side chains, the method comprising: forming the polymer into a permanent shape so that the polymer is substantially free of residual stress from the process by which the shape was attained; heating the polymer shape to a first deformation temperature and straining the article to a first temporary shape while cooling the article to a second temperature lower than the first deformation temperature, and setting the article in the first temporary shape at the second temperature; deforming the article from the first temporary shape to a second temporary shape, the deformation starting at a temperature no higher than the second temperature and cooling the article during and after such deformation to a third temperature lower than the second temperature to set the article in a second temporary shape; and deforming the article, at least one more time, to a third temporary shape starting at a temperature no higher than the third temperature and cooling the article during and after such deformation to a fourth temperature lower than the third temperature to set the article in a third temporary shape; the article then being stable in the third temporary shape at a desired temperature of use while being susceptible to successively returning to its second temporary shape and to its first temporary shape and to its permanent shape as it may be exposed to higher temperatures.