Non-DLVO, steric and fluctuation forces

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Steric forces between surfaces with end-grafted chains▶ End-grafted polymers : well understood- Each molecule is attached to the surface at one end- Coverage is fixed- Molecules do not interact either with each other or with the two surfaces- ex) Di-block copolymerOne block for anchoring, the other protruding into thesolvent to form polymer layerFig 14.3 Forces between twopolystyrene brush layers endgraftedonto mica surfaces intoluene▶ Measured forces agree with theoretical fits ofAlexander - de Gennes eqn.▶ No hysterisis on approach and separation ofpolymers
Steric forces between surfaces withphysisorbed layers I▶ No anchoring group that chemisorb to the surface▶ Binding to the surface via much weaker physical forces▶ Highly dynamic layers: Individual segments continually attaching and detaching from the surface: whole molecules slowly exchange with those in bulk solutionWhen two surface approach each other▶ Amount of adsorbed polymer changing▶ Number of binding sites per molecule changing▶ Different segments from the same coil bound to both surfaces Bridging▶ Long time to reach equilibrium▶ Hysteretic force profile
Page 1 and 2: Solvation, Structural andHydration
Page 3 and 4: Molecular Ordering at Surfaces, Int
Page 5 and 6: Origin of Main type of Solvation Fo
Page 7 and 8: Origin of Main type of Solvation Fo
Page 9 and 10: Measurements and Properties of Solv
Page 17 and 18: Solvation of Forces in Aqueous Syst
Page 19 and 20: Two types ofRepulsive ‘Hydration
Page 29 and 30: Chapter 14.Steric and Fluctuation F
Page 31 and 32: What is a Polymer ?‣ Polymer :Mac
Page 33 and 34: Polymers at SurfacesIn solution Che
Page 35 and 36: Theories of Steric Interaction ICon
Page 37: Theories of Steric Interaction IIIA
Page 41 and 42: Forces in Pure Polymer Liquids (Pol
Page 43 and 44: Attractive Intersegment Forces▶ P
Page 45 and 46: Attractive Bridging ForcesReuquirem
Page 47 and 48: Attractive Depletion Forces I▶ Po
Page 49 and 50: Non‐Equilibrium Aspects of Polyme
Page 51 and 52: Protrusion Forces I▶ Approaching
Page 53 and 54: Protrusion Forces III▶ The protru
Page 55 and 56: Undulation and Peristaltic Forces I

Non-DLVO, steric and fluctuation forces

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