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Volumn 19, Issue 3, 2003, Pages 916-923

Polymer brushes grafted from clay nanoparticles adsorbed on a planar substrate by free radical surface-initiated polymerization

Author keywords

[No Author keywords available]

Indexed keywords

ADSORPTION; CLAY; CONFORMATIONS; DENSITY (SPECIFIC GRAVITY); FREE RADICAL POLYMERIZATION; GLASS; GRAFTING (CHEMICAL); MOLECULAR WEIGHT; NANOSTRUCTURED MATERIALS; SILICON WAFERS; STABILITY; SURFACES;

EID: 0037417986     PISSN: 07437463     EISSN: None     Source Type: Journal    
DOI: 10.1021/la026039u     Document Type: Article
Times cited : (102)

References (52)
  • 34
    • 0013052115 scopus 로고    scopus 로고
    • note
    • The substrates were soaked in Piranha solution (3:7 v/v) mixture of 30% (w/w) hydrogen peroxide and 98% (w/w) sulfuric acid, 15 min for silicon wafer and 1 min for gold substrates) and thoroughly rinsed by sonication in a deionized water bath. The purpose for the above process was to create a fresh and clean surface suitable for the next step of SAM formation. The precleaned silicon wafer pieces were submerged into freshly distilled toluene along with 0.5 wt % of APS (Aldrich) for 30 min. The substrates were then sonicated with toluene, acetone, and deionized water and stored in 0.1 M HCl overnight for protonation Gold surfaces were modified by dipping them into 5 mM solution of 2-(dimethylamino)ethanethiol hydrochloride (aldrich) in ethanol for 1 h, followed by thorough rinsing by ethanol. The purpose of the above pretreatment process was to generate a positively charged SAM of silane or thiol for the subsequent clay layer adsorption. Water contact angle measurements were taken before and after SAM to ensure surface functionalization by monitoring the change in hydrophilicity of the substrates.
  • 36
    • 0013098651 scopus 로고    scopus 로고
    • note
    • Small symmetrical peaks to the left of the primary Si 2s and Si 2p lines are shake-up satellite peaks formed by valence electrons reorganization sometimes observed with the spectrum of silicon wafers. The rest of the photoelectron lines and secondary structures agree very well with the chemical species present in the sample. Signals of Mg and Al (relatively very small stoichiometrically as compared to Si and O) in the monolayer of clay are too weak to be detected.
  • 44
    • 0013148790 scopus 로고    scopus 로고
    • note
    • 1/2]. For example, when the thickness is 18 nm, the molecular weight calculated from the above equation is MV = 39 728 g/mol.
  • 45
    • 0013148791 scopus 로고    scopus 로고
    • note
    • n would be based on accurate determination of the film thickness and surface density of the tethered polymer.
  • 48
    • 0013094030 scopus 로고    scopus 로고
    • note
    • Note that the interface of the flat surface is composed of a high concentration of growing chain ends confined in a limited two-dimensional area
  • 50
    • 0013051099 scopus 로고    scopus 로고
    • note
    • A large difference in surface tension can prevent the flux of monomer (typically nonpolar) at surfaces creating a more heterogeneous interfacial polymerization mechanism. A basic assumption on the theoretical treatment by Wittmer was that many simultaneously growing (essentially living) chains compete for the small influx of monomers to the surface. In this case, the difference between polarities at the interface and the nonpolar solvent subphase may prevent a homogeneous monomer influx. In effect, the polymerization system becomes a self-limiting heterogeneous system preventing formation of inherently high MW brushes. Also, the presence of any free initiators in solution competes with the polymerization of monomers, leaving less monomers available for polymerization at the interface and hence lower MW brushes.
  • 51


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.