Table III.
Advancing and static water contact angles (θA and θs) above and below the LCST of pNIPAAm retained on (Top) spin-coated APTES cured for different periods of time at 160 °C and (Bottom) various noncured silane layers. The pNIPAAm film was cured on the silane layer for 3 days in vacuum at 160 °C and then rinsed with cold DI water prior to the contact angle measurements. The average and standard derivation were obtained from four to six measurements.
| Curing time (h) | θA (deg) at 40 °C > LCST | θA (deg) at 25 °C < LCST | θs (deg) at 40 °C > LCST | θs (deg) at 25 °C < LCST |
|---|---|---|---|---|
| 0 | 87.1 ± 2.0 | 80.6 ± 2.7 | 72.6 ± 1.4 | 63.5 ± 1.9 |
| 1 | 91.1 ± 2.2 | 77.1 ± 4.5 | 73.0 ± 0.8 | 64.2 ± 1.1 |
| 2 | 86.0 ± 1.3 | 70.3 ± 2.0 | 72.2 ± 2.6 | 59.8 ± 1.7 |
| 4 | 86.3 ± 1.7 | 70.1 ± 1.9 | 70.3 ± 3.0 | 57.2 ± 1.2 |
| 6 | 83.9 ± 1.6 | 72.1 ± 1.5 | 67.5 ± 3.0 | 60.3 ± 3.2 |
| 14 | 83.3 ± 2.1 | 74.3 ± 2.9 | 73.0 ± 0.8 | 63.4 ± 2.0 |
| APTESa | 88.1 ± 3.3 | 88.3 ± 2.5 | 82.6 ± 0.6 | 82.7 ± 2.4 |
| SiOx or silane | θA (deg) at 40 °C > LCST | θA (deg) at 25 °C < LCST | θs (deg) at 40 °C > LCST | θs (deg) at 25 °C < LCST |
| SiOx | 58.5 ± 2.1 | 47.6 ± 3.6 | 53.6 ± 2.2 | 45.8 ± 2.5 |
| APTES | 87.1 ± 2.0 | 79.4 ± 3.4 | 70.0 ± 3.1 | 61.8 ± 2.2 |
| MPTMS | 92.9 ± 2.8 | 83.3 ± 2.4 | 79.0 ± 3.2 | 63.0 ± 2.4 |
| TESBA | 80.8 ± 1.8 | 73.8 ± 2.5 | 69.2 ± 3.3 | 49.9 ± 1.7 |
a
This is the cured APTES layer without pNIPAAm on top.