IDEALS Home University of Illinois at Urbana-Champaign logo The Alma Mater The Main Quad

Role of surface chemistry in sub-Einstein rheology of nano-composites

Show full item record

Bookmark or cite this item: http://hdl.handle.net/2142/34404

Files in this item

File Description Format
PDF Ranka_Moulik.pdf (949KB) (no description provided) PDF
Title: Role of surface chemistry in sub-Einstein rheology of nano-composites
Author(s): Ranka, Moulik
Advisor(s): Zukoski, Charles F.
Department / Program: Chemical & Biomolecular Engr
Discipline: Chemical Engineering
Degree Granting Institution: University of Illinois at Urbana-Champaign
Degree: M.S.
Genre: Thesis
Subject(s): polyhedral oligomeric silisequioxane (POSS) Rheology Nano-Composite Intrinsic Viscosity
Abstract: Sub-Einstein and negative intrinsic viscosities resulting from the addition of nano-fillers to polymer melts approximately 2-10 nm diameter have been reported. Here we explore the intrinsic viscosity of polyhedral oligomeric silisequioxane (POSS) particles of approximately 1.6-2.5 nm diameters as a function of polymer molecular weight. These nanoparticles consist of cubes of 8-corner silicon atoms edge bridged with oxygen atoms. A variety of functional groups are attached to the corner silicon atoms. Three different POSS particles are explored: POSS with 8 tethered alkyl chains (butyl and octyl) and POSS with 8 tethered polyethylene glycol, PEG, chains of degree of polymerization, n ~ 13 segments. The tethered particles are dissolved in a homopolymer matrix (polydimethyl siloxane, PDMS, for octyl-POSS and butyl-POSS and PEG for PEG-POSS). The POSS intrinsic viscosity drops with increasing polymer matrix molecular weight from approximately 2.5 (as predicted by Einstein for no slip boundary conditions) to negative values. We discuss these results in light of previous studies of the intrinsic viscosity of nanoparticles in polymer melts with special attention to particle-polymer segment surface interactions that result in particle-polymer miscibility and ideas based on the ability of nanoparticles to alter polymer relaxation rates. We develop a hypothesis that negative intrinsic viscosities are associated with weak particle-polymer segment surface interactions while at the same time developing mechanisms that ensure particles remain soluble in the polymer melt.
Issue Date: 2012-09-18
URI: http://hdl.handle.net/2142/34404
Rights Information: Copyright 2012 Moulik Ranka
Date Available in IDEALS: 2012-09-18
Date Deposited: 2012-08
 

This item appears in the following Collection(s)

Show full item record

Item Statistics

  • Total Downloads: 157
  • Downloads this Month: 7
  • Downloads Today: 0

Browse

My Account

Information

Access Key