Table 2. Fractional Factorial Design Parameters for IPN Hydrogels.
Parameters examined in forming the secondary interpenetrating PAA network included: the concentration of acrylic acid relative to the concentration of hydrated acrylamide repeat units (C Value); the initiator to total monomer molar ratio; the percentage of total monomer that was crosslinker; and the ionic strength.
| Level | C Value | Initiator / Monomer mol Ratio |
MBAAmmol % |
Ionic Strength (mol/L) |
|
| Low (−1) | 0.5 | 0.003 | 0.25 | 0.0 | |
| Center (0) | 1.0 | 0.009 | 0.50 | 0.4 | |
| High (+1) | 1.5 | 0.015 | 0.75 | 0.8 | |
| Formulation | C Value | Initiator / Monomer mol Ratio |
MBAAmmol % |
Ionic Strength (mol/L) |
Max RSM in 0.5 mmol/LHCl* |
| 1 | 1 | −1 | −1 | 1 | 4.84 +/− 0.24 |
| 2 | 1 | −1 | 1 | −1 | 4.68 +/− 0.12 |
| 3 | 1 | 1 | −1 | −1 | 4.84 +/− 0.02 |
| 4 | −1 | 1 | −1 | 1 | 7.05 +/− 0.09 |
| 5 | −1 | 1 | 1 | −1 | 7.89 +/− 0.25 |
| 6 | −1 | −1 | −1 | −1 | 7.46 +/− 0.11 |
| 7 | 1 | 1 | 1 | 1 | 4.68 +/− 0.19 |
| 8 | 0 | 0 | 0 | 0 | 5.14 +/− 0.05 |
| 9 | −1 | −1 | 1 | 1 | 6.94 +/− 0.12 |
| 10 | 0 | 0 | 0 | −1 | 4.93 +/− 0.13 |
*
HCl solution is 0.5 mmol/L HCl and 1.0 mmol/LNaCl