Fig. 2. (a) Snapshots of PNIPAM (12) and PNIPAM-co-MAA (12-4) systems in molecular dynamics (MD) simulation. The hydrogen bonds between the polymers and octanol (green colour) are represented by black lines and circles. O, N, H and C atoms in the polymers are coloured red, blue, white and cyan, respectively. (b) Radial distribution functions (RDFs) between hydrogen-bond acceptors and donors. (c) Total number of hydrogen bonds between the PNIPAM polymer and octanol, and between the NIPAM subunits or MAA groups of the PNIPAM-co-MAA polymer and octanol. Dynamic interfacial tension of the water–toluene interface for (d) 0.1 wt% PNIPAM-co-MAA microgels in different phases in the presence or absence of 0.5 vol% octanol and (e) 0.1 wt% PNIPAM-co-MAA microgels in the oil phase in the presence of different concentrations of octanol. (f) Dynamics of the PNIPAM-co-MAA polymer near the oil–water interface. The starting and the last frames of the simulation with the PNIPAM-co-MAA (3-1) polymer near and at the water–oil interface are shown in panels (f₁) and (f₄), respectively. (f₂) Hydrogen bonds (as black lines and circles) formed between PNIPAM-co-MAA (3-1) polymers and octanol close to the interface. (f₃) First arrival time of the polymer from the centre of the oil region to the interface. (g) Appearance of pendant drops at adsorption–desorption equilibrium during the volume reduction and expansion processes. Interfacial jamming and obvious wrinkles were appeared on the drop surface of Sample 3. Sample 3: deionized water – 0.1 wt% PNIPAM-co-MAA microgels (oil) + 0.5 vol% octanol (oil); Sample 7: 0.1 wt% PNIPAM-co-MAA microgels (water) – 0.5 vol% octanol (oil).