Switching (bio-) adhesion and friction in liquid by stimulus responsive polymer coatings

Polyelectrolytes as Building Blocks for Next-Generation Membranes with Advanced Functionalities

“…The conformation of PEs in brushes is different from neutral polymers in brushes. For neutral brushes, polymers stretch away from the surface due excluded volume interactions, , while PEBs swell by the high osmotic pressure induced by trapped counterions. , PEBs have gained a lot of attention because of their lubricious, , antifouling and stimuli-responsive , properties. For membrane applications, the latter two properties are of particular interest, so they will be treated in more detail in the next two sections, before discussing ways to increase the layer stability in section .…”

“…Since this stimulus can be applied externally, without the need to change the solution conditions, it provides an easy and effective control. The responsiveness of PEBs has made them popular systems for the design of functional surface coatings, because the swelling state of the brushes controls the surface properties of the coating . Therefore, they can be used in the development of smart adhesives, − switchable lubricants, , and for wetting control. , Moreover, it allows for the controlled release of fouling components, which can be particularly useful in membrane applications.…”

Synthetic strategies to enhance the long-term stability of polymer brush coatings

“…chameleons. 20 Next to these bioinspired approaches, brushes can also be applied in smart adhesives, 21,22 energy devices, 23,24 bactericidal [25][26][27] and blood compatible 28,29 coatings, membranes, 30,31 nano-theranostics, 32 times the radius of gyration, the polymers do not interact and form mushrooms in good solvents. When these low-density polymers are in a poor solvent and/or strongly interacting with the substrate, pancakes instead of mushrooms are formed.…”

Surface-Grafted Poly(ionic liquid) that Lubricates in Both Non-polar and Polar Solvents

“…It is explained that the effective reduction in the sliding friction between two surfaces is due to a synergistic effect of resistance to penetration of the one surface into the polymers at the other contacting surface and the fluidity of these polymer brushes, which is a characteristic gained from the solvation layers surrounding the polymer brushes. 8 − 11 For example, poly[2-(methacryloyloxy)ethyl phosphorylcholine] showed an unparalleled lubrication performance, with a Coefficient of Friction (CoF, μ) as low as 0.00004 at pressures as high as 7.5 MPa, which is attributed primarily to the strong hydration of the phosphorylcholine-like monomer units known to bind around 15–25 or more water molecules. 12 The same principle was demonstrated in a nonaqueous environment whereby poly(alkyl methacrylates) brushes were examined in hexadecane.…”

“…Surface-grafted polymers are a commonly implemented strategy to render surface properties in effectively adjusting surface interactions by steric repulsion (nonionic polymer) and additional electrostatic interaction (polyelectrolyte). − Such a system has demonstrated a great ability to introduce exceptional lubrication capability in both biological and synthetic polymers that were immersed in a range of media. It is explained that the effective reduction in the sliding friction between two surfaces is due to a synergistic effect of resistance to penetration of the one surface into the polymers at the other contacting surface and the fluidity of these polymer brushes, which is a characteristic gained from the solvation layers surrounding the polymer brushes. − For example, poly­[2-(methacryloyloxy)­ethyl phosphorylcholine] showed an unparalleled lubrication performance, with a Coefficient of Friction (CoF, μ) as low as 0.00004 at pressures as high as 7.5 MPa, which is attributed primarily to the strong hydration of the phosphorylcholine-like monomer units known to bind around 15–25 or more water molecules . The same principle was demonstrated in a nonaqueous environment whereby poly­(alkyl methacrylates) brushes were examined in hexadecane .…”