Biomedical Engineering Reference
In-Depth Information
TABLE 3.9
Comparisons between Proposed Physical Loaded Manufacturing Technique
and Current State-of-the-Art Manufacturing Technique for IPMNCs
Current state-of-the-art
manufacturing technique
Proposed physical loaded
manufacturing technique
Fundamental processes
Chemical metal reducing processes
Physical metal loading processes
Choice of metal
Typically Pt, Au, and Pd
Not limited (Ag or graphite)
Process parameters
Multiple parameters including
chemical concentrations,
temperature, reaction time,
preliminary treatments, and so on
Only a few parameters including
particle loading pressure and
temperature
Estimated material price
~$10/cm
2
<$0.1/cm
2
Nominal production time
48 h
2 h
3.3.9
S
CALING
It is well understood that all commercially available (as-received) perfluorinated ion-
exchange polymers are in the form of hydrolyzed polymers, are semicrystalline, and
may contain ionic clusters. The membrane form of these polymers has a typical
thickness in the range of approximately 100-300
m. Such a thin thickness of
commercially available membranes permits fast mass transfer for use in various
chemical processes. Such as-received semicrystalline membranes are not melt pro-
cessable, so they are not suitable for the fabrication of three-dimensional electroac-
tive materials or other composite forms.
In the previous work (Kim and Shahinpoor, 2001a), the authors reported a newly
developed fabrication method that can scale up or down the IPMNC artificial muscles
in a strip size of micro- to centimeter thickness. We have adopted a recently devel-
oped technique by Moor et al. (1992) for dissolving as-received ion-exchange mem-
branes in appropriate solvents. By carefully evaporating solvents out of the solution,
recast ion-exchange membranes were obtained (Gebel et al., 1987; Moor et al.). A
number of samples are shown in figure 3.57.
The preparation of a solution recast Nafion film sample includes:
µ
1.
DuPont liquid Nafion solution was purchased.
2.
According to manufacturer's specification, this solution contains 10% Nafion
and 90% solvent of approximately one-to-one mixture of 2-butanol and water.
3.
It was noted, initially, that during the solvent evaporation the solidified
Nafion developed surface cracks. Therefore, an essential trick was to
introduce an additive that makes the solvent mixture act like an azeotrope.
4.
The use of DMF was successful. Subsequently, when given a multiple
layer of liquid Nafion dried, an approximately 2-mm thick sample was
prepared successfully.
5.
First, a known quantity of liquid Nafion with an additive is placed in a
Teflon (polytetrafluoroethylene, PTFE)-coated Pyrex glass.
