5420 microscope

The topography was determined using an atomic force microscope (AFM; 5420 microscope, Agilent Technologies, Santa Clara, CA, USA). Gel/CS/PVA hydrogel films were dehydrated at a controlled temperature of 50 °C in a convection oven (Luzeren, Hangzhou, China) and later placed in a desiccator until observation to avoid hydration due to relative humidity. For each sample, three random regions were examined with a scan size of 4 × 4 μm². Measurements were performed in contact mode under ambient conditions with silicon tips (CSC11, Silicon-MDT, Moscow, Russia) taking images at a scanning rate of 3 lines/s. Moreover, at least three samples were measured for each kind of Gel/CS/PVA hydrogel. The AFM images were analyzed with WSxM 4.0 free software (Develop 8.6).

The topography was determined using an atomic force microscope (AFM; 5420 microscope, Agilent Technologies, Santa Clara, CA, USA). Gel/CS/PVA hydrogel films were dehydrated at a controlled temperature of 50 °C in a convection oven (Luzeren, Hangzhou, China) and later placed in a desiccator until observation to avoid hydration due to relative humidity. For each sample, three random regions were examined with a scan size of 4 × 4 μm². Measurements were performed in contact mode under ambient conditions with silicon tips (CSC11, Silicon-MDT, Moscow, Russia) taking images at a scanning rate of 3 lines/s. Moreover, at least three samples were measured for each kind of Gel/CS/PVA hydrogel. The AFM images were analyzed with WSxM 4.0 free software (Develop 8.6).

Tapping mode AFM was performed on an Agilent 5420 microscope (Santa Clara, CA, USA) under ambient conditions using engagement setpoints between 0.9–0.95 of the free amplitude oscillation. The tapping mode cantilevers (BudgetSensors, Sofia, Bulgaria and Bruker, Billerica, MA, USA) had a resonant frequency of 300 kHz and a force constant of 40 N/m. For imaging the film/substrate interface, the PLA-removed thin films were placed upside down on double-sided transparent tape (ScotchBrand, St. Paul, MN, USA) and placed in liquid N₂ for 30 s. Following liquid N₂ exposure, the Si wafer was peeled away from the film providing access to the underside. These films were again exposed to a 10–20 s O₂ reactive ion etch (150 W 50 KHz in 100 mTorr) on the underside to remove any HMDS, a thin PS wetting layer or adhesive residue [34 (link),61 (link)].