Nanorheology of Confined Polymer Melts. 1. Linear Shear Response at Strongly Adsorbing Surfaces

Granick, Steve; Hu, Hsuan-Wei; Carson, George A.

doi:10.1021/la00022a076

Cited by 116 publications

(159 citation statements)

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“…[6][7][8] The linear viscoelastic properties of atactic polyphenylmethylsiloxane ͑PPMS͒ were studied at strongly adsorbing ͑mica͒ as well as weakly adsorbing ͑mica coated with self-assembled monolayers of condensed octadecyltriethoxysilane͒ surfaces. ͑PPMS has a very low bulk glass transition temperature, T g ϭϪ20°C, and the bulk glass transition therefore does not interfere with experiments on confined systems.͒ For PPMS confined between strongly adsorbing surfaces, the following observations were made.…”

Section: Introductionmentioning

confidence: 99%

Molecular simulation and continuum mechanics investigation of viscoelastic properties of fluids confined to molecularly thin films

Khare

Pablo

Yethiraj

2001

The Journal of Chemical Physics

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A combination of molecular dynamics simulations of oscillatory shear flow and continuum mechanics is used to investigate viscoelastic properties of materials confined to molecularly thin films. The atoms of the simple liquid interact via a repulsive Lennard-Jones potential. The chain molecules are modeled as strings of similar spheres connected via finite extensible nonlinear elastic springs. The fluid is confined between two surfaces composed of identical spheres that are moved to simulate oscillatory flow. In order to mimic experiments, the temperature is controlled by coupling the wall atoms to a heat bath, and the viscoelastic properties are obtained via an analysis using continuum mechanics. Both simple and polymeric fluids exhibit linear viscoelastic behavior under typical simulation conditions, although inertial effects play an important role in determining the flow behavior. Simple fluids display a smooth transition from liquidlike to solidlike behavior when confined to molecularly thin films, whereas linear chain polymers and gels display predominantly elastic shear response at all frequencies investigated. These results are in qualitative agreement with the surface forces apparatus experiments on similar systems.

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Section: Introductionmentioning

confidence: 99%

Molecular simulation and continuum mechanics investigation of viscoelastic properties of fluids confined to molecularly thin films

Khare

Pablo

Yethiraj

2001

The Journal of Chemical Physics

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“…Similar measurements on much larger area contacts have been made with the surface forces apparatus [14,15] and microscopic sphere-onflat contacts [16]. SMS is also closely related to friction loop methods [17] and to force modulation spectroscopy [18,19].…”

Section: Basics Of Shear Modulation Spectroscopymentioning

confidence: 63%

Formation of Nanometer-Scale Contacts to Viscoelastic Materials

Wahl¹,

Unertl²

2007

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The making and breaking of nanometer-scale contacts is an essential operation in MEMS devices with moving parts. The behavior of contacts in this size range is not well understood, especially if viscoelastic materials are involved. This article describes shear modulation spectroscopy, a new scanning force microscope technique especially well suited for quantitative studies of nanometer-scale contacts to viscoelastic materials such as lubricants and some polymers. The technique is illustrated by measurements and analysis of contacts to poly(vinylethylene).

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“…[26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] Montfort and Hadziioannou, for instance, confined nanometer thick films of long chain molecules between mica sheets and measured the static forces as the two SFA surfaces engaged each other 28 . As illustrated in Figure 4, repulsive forces were found to extend beyond separation distances of 10 times the radius of gyration, R g , determined for the bulk.…”

Section: Structurally Constrained Systemsmentioning

confidence: 99%