【正文】 mperatures were 274 K for the standardlow Tg, 328 K for the standard high Tg and 280 K for the novel latex.The microstructural analysis was carriedout on an FEI XL30 environmental scanning electron microscope equipped with a Peltier stage. Wet samples from the above formulations were placed onto the cooling stage in the microscope chamber at a temperature of ca. 274 K. An evaporationinhibiting pumpdown sequence was then performed, with the ambient air progressively replaced by water vapour. Once the purging cycle was pleted, water vapour pressures and workingdistances of – Torr and – mm were set, which provided optimal imaging environments, . sufficient resolution and minimal beam damage. Imaging of the specimens was carried out at an accelerat ing voltage of 10 kV. Increasing the tem perature of the specimens by 1 or 2 degrees above the starting temperature of 273 K, as explained above, resulted in further dehydration of the latices, which allowed examination of the process of film formation.Results and DiscussionPrior to considering the results from the ESEM examination, it is important to note that when we refer to latices as being ‘wet’, some water has in actual fact been removed from the surface of the specimens in order to obtain better quality images. Keddie et al.[1,4] used a similar approach in the study of latex film formation by means of ESEM. It was found that despite the fact that some of the surface water had been removed, the bulk of the samples remained‘wet’.Standard Latex – low TgFrom the ESEM images of the standard low Tg latex (Figure 2), it can be seen that under ‘wet’ conditions (Figure 2a) the microstructure of the specimen consists mainly of randomly distributed individual particles with an average size of ca. 300 nm. Due to the fact that some of the water has already been removed, as explained above, some of the polymer particles are in contact. Despite that, they are still physi cally distinct, . no significant deformation has occurred, and therefore it can be concluded that the latex is in Stage II/II . By increasing the temperature of the specimen (Figure 2b), water evaporation takes place, which resulted in the formation of a continuous polymer film. However, due to the fact that not all particles have lost their identity and boundaries are still clearly visible, it can be concluded that under these conditions the latex is in StageCopyright 2009 WILEYVCH Verlag GmbH amp。 Stage IV – a molecularly continuous and homogeneous film formed as a result of polymer interdiffusion.In 1995, Keddie et al. [4] used environmental scanning electron microscopy (ESEM) and MultipleAngleofIncidence Ellipsometry (MAIE) in the study of latex film formation. They concluded that an intermediate stage, between II and III, has been omitted in the conventionaldescriptions.[9–17] The stage, defined as II , is characterized by a randomly packed array of deformed particles which still contain waterfilled interstices. A schematic representation of the process is shown in Figure 1.More recently, Keddie et al.[18,19] investigated the possibility of creating hetero geneous films, by mixing carbon nanotubes (CNTs) with waterborne polymer particles. It was found that the mechanical properties of the nanoposite coatings can be greatly improved, while maintaining their optical clarity. However, it is important to note that all of the above studies were carried out using continuous polymer films.In this paper we present the results from an ESEM investigation into the film for mation mechanisms of novel acrylic latex, which has been stabilised by using a new polysaccharide, derived from agricultural waste, and two standard polymer systems, where the conventional carboxymethyl cellulose (CMC) has been used as a stabiliser. The novel polysaccharide con sists of a number of monosaccharides (including arabinose and xylose) formed from five and sixmembered rings and has a low molecular weight, only a few thousand rather than the hundreds of thousands found in cellulose for exam ple. The polysaccharide also contains aCopyright 2009 WILEYVCH Verlag GmbH amp。 Stage II – concen trated suspension of particles in contact with each other, surrounded by solvent filled interstices。 Soft Systems, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge, CB30HE, UKEmail: kd2812 ICI Paints, Slough, Berkshire, SL2 5DS, UK3 ICI Wilton Applied Research Group, The WiltonCentre, Redcar, TS10 4RF, UKimaging ‘wet’ and insulating specimens, has been successfully used in the study of a number of systems and dynamic processes including latices and film formation.[2–6]ESEM is based on the use of a multiple aperture graduated vacuum system, which allows specimens to be imaged under water vapour or other auxiliary gases, suc