Surface Forces between Adsorbed Quaternarized Poly(2-vinylpyridine) Layers:  Molecular Rearrangements and Bridging Interactions

Maurdev, George; Meagher, Laurence; Ennis, Jonathan; Gee, Michelle L.

doi:10.1021/ma001237i

Cited by 20 publications

(29 citation statements)

References 22 publications

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“…The general features of hysteresis loops were similar for all acids showing sharp transitions in the swelling and contraction of the P2VP layers in both pH decrease and increase cycles. Note that the p K a value measured from the inversion point in the pH decrease curve (pK a = 3.2) is much lower than typical pK a values of P2VP (p K a ≈ 5.2) measured in dilute solutions 41, 42. We attribute this deviation partly to the Donnan potential that results in partial exclusion of protons from the membrane structure to the external solution.…”

Section: Resultsmentioning

confidence: 61%

Control of Optical Hysteresis in Block Copolymer Photonic Gels: A Step Towards Wet Photonic Memory Films

Kim

Kang

Baek

et al. 2010

Adv Funct Materials

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Polystyrene‐block‐poly(2‐vinyl pyridine) (PS‐b‐P2VP) block copolymer photonic gels are fabricated that exhibit controllable optical hysteresis in response to a cyclic pH sweep. The optical hysteresis is tuned by controlling the ion‐pairing affinity between various anions and the protonated pyridinium ions on the P2VP block, which is highly dependent on the hydration energy of the ions, the dielectric constant of the solvent, and the ionic strength of the medium. The pH coercivity defining the magnitude of hysteresis of the photonic gels could be varied from 0.26 to 7.4. Photonic gel films with strong optical hysteresis can serve as wet photonic memory films where information can be cyclically recorded and erased at least 15 times and maintained for at least 96 h. The memory colors can be further tuned by selection of the copolymer molecular weight.

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Section: Resultsmentioning

confidence: 61%

Control of Optical Hysteresis in Block Copolymer Photonic Gels: A Step Towards Wet Photonic Memory Films

Kim

Kang

Baek

et al. 2010

Adv Funct Materials

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“…48,107 Double layer forces were observed between silica, mica, or functionalized surfaces in the presence of various oppositely charged PEs. 72,109,[167][168][169][170][171][172][173][174][175] The strength of double layer forces could also be varied through solution pH. 72,147,176 This dependence originates from the resulting variation of the dissociation degree of the PE.…”

Section: Bare Surfaces and Surfaces With Saturated Pe Layersmentioning

confidence: 99%

Polyelectrolyte adsorption, interparticle forces, and colloidal aggregation

et al. 2014

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This review summarizes the current understanding of adsorption of polyelectrolytes to oppositely charged solid substrates, the resulting interaction forces between such substrates, and consequences for colloidal particle aggregation. The following conclusions can be reached based on experimental findings. Polyelectrolytes adsorb to oppositely charged solid substrates irreversibly up to saturation, whereby loose and thin monolayers are formed. The adsorbed polyelectrolytes normally carry a substantial amount of charge, which leads to a charge reversal. Frequently, the adsorbed films are laterally heterogeneous. With increasing salt levels, the adsorbed mass increases leading to thicker and more homogeneous films. Interaction forces between surfaces coated with saturated polyelectrolyte layers are governed at low salt levels by repulsive electric double layer interactions, and particle suspensions are stable under these conditions. At appropriately high salt levels, the forces become attractive, principally due to van der Waals interactions, but eventually also through other forces, and suspensions become unstable. This situation can be rationalized with the classical theory of Derjaguin, Landau, Verwey, and Overbeek (DLVO). Due to the irreversible nature of the adsorption process, stable unsaturated layers form in colloidal particle suspensions at lower polyelectrolyte doses. An unsaturated polyelectrolyte layer can neutralize the overall particle surface charge. Away from the charge reversal point, electric double layer forces are dominant and particle suspensions are stable. As the charge reversal point is approached, attractive van der Waals forces become important, and particle suspensions become unstable. This behaviour is again in line with the DLVO theory, which may even apply quantitatively, provided the polyelectrolyte films are sufficiently laterally homogeneous. For heterogeneous films, additional attractive patch-charge interactions may become important. Depletion interactions may also lead to attractive forces and suspension destabilization, but such interactions become important only at high polyelectrolyte concentrations.

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“…Let us first discuss the adhesive minimum at short separations; 20-30 Å. This is primarily generated by attractive bridging interactions [7][8][9][23][24][25][26][27]. We note that the adhesive minimum becomes stronger and more short-ranged if we:…”

Section: Changing End Block Sizementioning

confidence: 99%