title: Bond Tension in Tethered Macromolecules.
abstract: The paper presents scaling analysis of mechanical tension generated in densely branched macromolecules tethered to a solid substrate with a short linker. Steric repulsion between branches results inz-fold amplification of tension in the linker, wherezis the number of chain-like arms. At largez~ 100-1000, the generated tension may exceed the strength of covalent bonds and sever the linker. Two types of molecular architectures were considered: polymer stars and polymer "bottlebrushes" tethered to a solid substrate. Depending on the grafting density, one distinguishes the so-called mushroom, loose grafting, and dense grafting regimes. In isolated (mushroom) and loosely tethered bottlebrushes, the linker tension is by a factor of [Formula: see text] smaller than the tension in a tethered star with the same number of armsz. In densely tethered stars, the effect of interchain distance (d) and number of arms (z) on the magnitude of linker tension is given byf≅f0z3/2(b/d) for stars in a solvent environment andf≅f0z2(b/d)2for dry stars, wherebis the Kuhn length andf0≅kBT/bis intrinsic bond tension. These relations are also valid for tethered bottlebrushes with long side chains. However, unlike molecular stars, bottlebrushes demonstrate variation of tension along the backbonef≅f0s z1/2/das a function of distancesfrom the free end of the backbone. In dense brushes [Formula: see text] withz≅ 1000, the backbone tension increases fromf≅f0= 1 pN at the free end of the backbone (s≅b) to its maximumf≅zf0≅ 1nNat the linker to the substrate (s≅zb).
authors: Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States.
authors: Sergei S
authors: SS
authors: Sheiko
authors: P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow 117924, Russia.
authors: Sergey
authors: S
authors: Panyukov
authors: Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States.
authors: Michael
authors: M
authors: Rubinstein