PMID- 15518505
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20060410
LR  - 20041102
IS  - 0743-7463 (Print)
IS  - 0743-7463 (Linking)
VI  - 20
IP  - 23
DP  - 2004 Nov 9
TI  - Thermoresponsive poly(N-isopropylacrylamide) copolymers: contact angles and 
      surface energies of polymer films.
PG  - 10138-45
AB  - Surface properties of poly(N-isopropylacrylamide) (PNIPAM) copolymer films were 
      studied by contact angle measurements and optical and atomic force microscopy. We 
      prepared a series of copolymers of N-isopropylacrylamide with 
      N-tert-butylacrylamide (NtBA) in order of increasing hydrophobicity. The 
      measurements of the advancing contact angle of water at 37 degrees C were 
      hampered by the observation of a distinct stick/slip pattern on all polymers in 
      the series with the exception of poly(NtBA) (PNtBA). We attributed this behavior 
      to the film deformation by the vertical component of liquid surface tension 
      leading to the pinning of the moving contact line. This was confirmed by the 
      observation of a ridge formed at the pinned contact line by optical microscopy. 
      However, meaningful contact (without the stick/slip pattern and with a 
      time-independent advancing contact angle) angles for this thermoresponsive 
      polymer series could be obtained with carefully selected organic liquids. We used 
      the Li and Neumann equation of state to calculate the surface energy and contact 
      angles of water for all polymers in the series of copolymers and van Oss, 
      Chaudhury, and Good (vOCG) acid-base theory for PNtBA. The surface energies of 
      the thermoresponsive polymers were in the range of 38.9 mJ/m2 (PNIPAM) to 31 
      mJ/m2 (PNtBA) from the equation of state approach. The surface energy of PNtBA 
      calculated using vOCG theory was 29.0 mJ/m2. The calculated contact angle for 
      PNIPAM (74.5 +/- 0.2 degrees ) is compared with previously reported contact 
      angles obtained for PNIPAM-modified surfaces.
FAU - Gilcreest, Vincent P
AU  - Gilcreest VP
AD  - Chemistry Department, University College Dublin, Belfield, Dublin 4, Ireland.
FAU - Carroll, William M
AU  - Carroll WM
FAU - Rochev, Yuri A
AU  - Rochev YA
FAU - Blute, Irena
AU  - Blute I
FAU - Dawson, Kenneth A
AU  - Dawson KA
FAU - Gorelov, Alexander V
AU  - Gorelov AV
LA  - eng
PT  - Journal Article
PL  - United States
TA  - Langmuir
JT  - Langmuir : the ACS journal of surfaces and colloids
JID - 9882736
EDAT- 2004/11/03 09:00
MHDA- 2004/11/03 09:01
CRDT- 2004/11/03 09:00
PHST- 2004/11/03 09:00 [pubmed]
PHST- 2004/11/03 09:01 [medline]
PHST- 2004/11/03 09:00 [entrez]
AID - 10.1021/la0487996 [doi]
PST - ppublish
SO  - Langmuir. 2004 Nov 9;20(23):10138-45. doi: 10.1021/la0487996.