PMID- 21696203
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20111103
LR  - 20110726
IS  - 1520-5827 (Electronic)
IS  - 0743-7463 (Linking)
VI  - 27
IP  - 15
DP  - 2011 Aug 2
TI  - Interfacial friction and adhesion of polymer brushes.
PG  - 9387-95
LID - 10.1021/la201396m [doi]
AB  - A bead-probe lateral force microscopy (LFM) technique is used to characterize the 
      interfacial friction and adhesion properties of polymer brushes. Our measurements 
      attempt to relate the physical structure and chemical characteristics of the 
      brush to their properties as thin-film, tethered lubricants. Brushes are 
      synthesized at several chain lengths and surface coverages from polymer chains of 
      polydimethylsiloxane (PDMS), polystyrene (PS), and a poly(propylene 
      glycol)-poly(ethylene glycol) block copolymer (PPG/PEG). At high surface 
      coverage, PDMS brushes manifest friction coefficients (COFs) that are among the 
      lowest recorded for a dry lubricant film (mu  approximately  0.0024) and close to 1 order of 
      magnitude lower than the COF of a bare silicon surface. Brushes synthesized from 
      higher molar mass chains exhibit higher friction forces than those created using 
      lower molar mass polymers. Increased grafting density of chains in the brush 
      significantly reduces the COF by creating a uniform surface of stretched chains 
      with a decreased surface viscosity. Brushes with lower surface tension and 
      interfacial shear stresses manifest the lowest COF. In particular, PDMS chains 
      exhibit COFs lower than PS by a factor of 3.7 and lower than PPG/PEG by a factor 
      of 4.7. A scaling analysis conducted on the surface coverage (sigma) in relation to 
      the fraction (epsilon) of the friction force developing from adhesion predicts a 
      universal relation epsilon ~ sigma(4/3), which is supported by our experimental data.
FAU - Landherr, Lucas J T
AU  - Landherr LJ
AD  - School of Chemical & Biomolecular Engineering, Cornell University, Ithaca, New 
      York 14853-5201, USA.
FAU - Cohen, Claude
AU  - Cohen C
FAU - Agarwal, Praveen
AU  - Agarwal P
FAU - Archer, Lynden A
AU  - Archer LA
LA  - eng
PT  - Journal Article
DEP - 20110706
PL  - United States
TA  - Langmuir
JT  - Langmuir : the ACS journal of surfaces and colloids
JID - 9882736
EDAT- 2011/06/24 06:00
MHDA- 2011/06/24 06:01
CRDT- 2011/06/24 06:00
PHST- 2011/06/24 06:00 [entrez]
PHST- 2011/06/24 06:00 [pubmed]
PHST- 2011/06/24 06:01 [medline]
AID - 10.1021/la201396m [doi]
PST - ppublish
SO  - Langmuir. 2011 Aug 2;27(15):9387-95. doi: 10.1021/la201396m. Epub 2011 Jul 6.