PMID- 15072942
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20040810
LR  - 20040409
IS  - 0001-8686 (Print)
IS  - 0001-8686 (Linking)
VI  - 108-109
DP  - 2004 May 20
TI  - Interaction forces, deformation and nano-rheology of emulsion droplets as 
      determined by colloid probe AFM.
PG  - 197-205
AB  - Atomic force microscopy (AFM) has been used to determine the interaction forces 
      between a spherical silica probe and immobilised colloidal droplets of 
      polydimethylsiloxane (PDMS) in aqueous solution. Under mildly alkaline conditions 
      where PDMS droplets and the silica probe are both negatively charged, a repulsive 
      force is evident that increases less rapidly on surface approach than expected 
      for electrical double layer interaction of rigid particles. The departure from 
      hard-sphere behaviour enables the extent of droplet deformation to be determined 
      and by varying the extent of internal cross-linking within the PDMS droplets, the 
      influence of bulk rheology and interfacial tension on droplet deformation and 
      nano-rheology has been isolated. For highly cross-linked droplets, the extent of 
      deformation is controlled by the bulk rheology rather than the droplet's 
      interfacial properties. Upon retraction of the surfaces, force curve hysteresis 
      is observed and is due to the viscoelastic response of the PDMS. The extent of 
      hysteresis is dependent on the rate of approach/retraction and the loading force, 
      and has been theoretically fitted to obtain nano-rheological parameters, which 
      describe the droplet relaxation processes. For liquid-like droplets, with a low 
      level of cross-linking, no force curve hysteresis is observed and the elastic 
      deformation may be described by a single spring constant. The spring constant is 
      proportional to the surface tension (as controlled by surfactant adsorption) and 
      the reciprocal of the droplet radius, i.e. the Laplace pressure exclusively 
      controls droplet deformation. These colloid probe AFM studies offer due insight 
      into the deformation and interaction of emulsion droplets and have implications 
      when considering the stability, adhesion and processing of emulsions.
FAU - Gillies, Graeme
AU  - Gillies G
AD  - Ian Wark Research Institute, The ARC Special Research Centre for Particle and 
      Material Interfaces, University of South Australia, Mawson Lakes, South Australia 
      5095, Australia.
FAU - Prestidge, Clive A
AU  - Prestidge CA
LA  - eng
PT  - Journal Article
PL  - Netherlands
TA  - Adv Colloid Interface Sci
JT  - Advances in colloid and interface science
JID - 8706645
EDAT- 2004/04/10 05:00
MHDA- 2004/04/10 05:01
CRDT- 2004/04/10 05:00
PHST- 2004/04/10 05:00 [pubmed]
PHST- 2004/04/10 05:01 [medline]
PHST- 2004/04/10 05:00 [entrez]
AID - S0001-8686(03)00151-9 [pii]
AID - 10.1016/j.cis.2003.10.007 [doi]
PST - ppublish
SO  - Adv Colloid Interface Sci. 2004 May 20;108-109:197-205. doi: 
      10.1016/j.cis.2003.10.007.