Table 1. Positron Annihilation Lifetime Spectroscopy (PALS) Data for the PEG Hydrogelsa.
| sample | χ2 (a.u.) | Io-Ps (%) | Io-Ps (ns) | σo-Ps (ns) | rFV (Å) | VF (Å3) | σVF (Å3) |
|---|---|---|---|---|---|---|---|
| PEG5 | 1.08 | 20 ± 1 | 1.95 ± 0.06 | 0.3 ± 0.1 | 2.80 ± 0.09 | 92 ± 6 | 30 ± 10 |
| PEG7 | 1.02 | 20 ± 1 | 1.97 ± 0.08 | 0.3 ± 0.1 | 2.82 ± 0.08 | 94 ± 7 | 30 ± 10 |
| PEG10 | 1.05 | 20.0 ± 0.3 | 1.97 ± 0.02 | 0.4 ± 0.3 | 2.82 ± 0.03 | 94 ± 2 | 40 ± 30 |
| PEG25 | 1.06 | 17.0 ± 0.5 | 2.46 ± 0.06 | 0.5 ± 0.1 | 3.24 ± 0.08 | 142 ± 6 | 80 ± 10 |
a
Values of the intensity of the orthopositronium signal (Io-Ps), orthopositronium Lifetime (τo-Ps) and distribution (σo-Ps), average radius of the free volume voids (rFV), average volume of the free volume voids (VF) and distribution (σVF), and for the different PEG hydrogels tested. χ2 are the χ2 test values.