Structure of poly(N-isopropylacrylamide) brushes and steric stability of their grafted cellulose nanocrystal dispersions

  1. Get@NRC: Structure of poly(N-isopropylacrylamide) brushes and steric stability of their grafted cellulose nanocrystal dispersions (Opens in a new window)
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Journal titleJournal of Colloid and Interface Science
Pages157165; # of pages: 9
SubjectAcrylic monomers; Brushes; Cellulose derivatives; Colloids; Convergence of numerical methods; Dynamic light scattering; Film thickness; Living polymerization; Phase separation; Scanning electron microscopy; Stabilization; Temperature; Cellulose nano-crystals; Cellulose nanocrystal (CNC); Hydrophobic attraction; Living radical polymerization; Poly (n isopropylacrylamide); Rod-like particles; Steric; Thermo-responsive behaviors; Grafting (chemical); amide; bromine; carbon; carbonyl derivative; cellulose; hydroxyl group; monomer; nanocrystal; nitrogen; oxygen; poly(n isopropylacrylamide); sulfate; article; chemical modification; chemical structure; diffusion coefficient; dispersion; film; gel permeation chromatography; hydrolysis; infrared spectroscopy; light scattering; macromolecule; molecular weight; phase separation; polymerization; priority journal; scanning electron microscopy; scanning transmission electron microscopy; surface charge; surface property; temperature; thickness; transition temperature; X ray photoelectron spectroscopy; zeta potential; Acrylic Compounds; Cellulose Derivatives; Colloids; Monomers; Optical Scattering; Polymerization; Scanning Electron Microscopy; Stabilization; Temperature
AbstractThermo-responsive poly (N-isopropylacrylamide) (poly(NIPAAm)) brushes were grafted from the surface of cellulose nanocrystals (CNC) via living radical polymerization (LRP) using different initiator and monomer concentrations. The dry film thickness of the poly(NIPAAm) layer around CNC was calculated based on Scanning Electron Microscopy (SEM) and dynamic light scattering (DLS) measurements. The wet film thicknesses of grafted poly(NIPAAm) brushes in water were calculated to be 15 and 9. nm for NIPAAm-CNC-1 and NIPAAm-CNC-2, respectively. Grafted chain densities and wet film thicknesses at below and above the critical temperature (T= 34. °C) of polyNIPAAm were calculated by applying mean-field analytical theory. The non-ionic poly(NIPAAm) brushes screened the surface charges of CNC particles, leading to a significant decrease in the absolute zeta potential values for the poly(NIPAAm) grafted CNCs compared to the unmodified and initiator modified CNC samples. Nevertheless, the colloidal stability of poly(NIPAAm) grafted CNC particles were still maintained by steric stabilization below the critical temperature On the other side, hydrophobic attractions among poly(NIPAAm) grafted CNC rods above 34. °C lead to coagulation and phase separation. While both poly(NIPAAm) grafted CNC samples showed thermo-responsive behavior, the reversibility of this temperature triggered property was dependent on grafting density. © 2014 Elsevier Inc.
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AffiliationNational Research Council Canada (NRC-CNRC); National Institute for Nanotechnology (NINT-INNT)
Peer reviewedYes
NPARC number21272146
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Record identifierd8d4f59f-ef94-4006-b778-c8ff7309b23f
Record created2014-07-23
Record modified2016-05-09
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