Breath figures

Blood alcohol concentration (BAG) is often based not on an actual sample of blood but rather on the concentration of alcohol in a sample of breath (Figure 3.3). Alcohol is volatile, and, as described by Henry s law, there is a constant relationship between the amount of alcohol vapor found in a volume of air (breath sample) and the amount of alcohol found in a volume of liquid (blood). All breath-testing equipment uses the blood-breath ratio of 2,100 1 for alcohol. This means that the amount of alcohol found in 2,100 milliliters of breath is equivalent to the amount of alcohol found in 1 milliliters of blood. 

Fig. 14 Optical micrographs of breath figures of hb-P20 obtained from its CS2 solutions by blow drying in a stream of moist air...

Another technique utilizing hquid droplets is breath figure templating, which was reported by Francois et al. [43-45]. Under the influence of a moist air flow, water droplets condense on the surface of a polymer solution. They form a hexagonal array and sink into the polymer solution, thereby serving as template. After complete evaporation of the solvent and water droplets, a polymer film remains with hexagonally arranged pores. 

Breath Figures Fabrication of Honeycomb Porous Films... 

One particular case of BF formation concerns the case of drying polymer solutions which, under appropriate conditions, can produce highly ordered porous materials, as first described by Francois et al. in 1994 [99]. This process regained popularity during the last decade [10, 98, 100-103]. Several studies reported the physical mechanisms [104, 105] underlying of the breath figures formation. 

Breath figures Condensation of water vapor Porous films with variable surface distribution and pore sizes Hundreds of nanometers up to 20 pm Water vapor condensation during solvent evaporation drives the formation of pores. Solvent, polymer concentration, temperature and relative humidity play a key role on the pore ftumation [9, 10, 98, 103, 121]... 

Munoz-Bonilla, A., Femandez-Garcia, M., Rodriguez-Hemandez, J. Towards hierarchically ordered functional porous polymeric surfaces prepared by the breath figures approach. Prog. Polym. Sci. 39(3), 510-514 (2014)... 

Escale, P., Rubatat, L., Billon, L., Save, M. Recent advances in honeycomb-structured porous polymer films prepared via breath figures. Eur. Polym. J. 48(6), 1001-1025 (2012)... 

Hemandez-Guerrero, M., Stenzel, M.H. Honeycomb structured polymer films via breath figures. Polym. Chem. 3(3), 563-577 (2012)... 

Made), W., Budkowski, A., Raezkowska, J., Rysz, J. Breath figures in polymer and polymer blend films spin-coated in dry and humid ambience. Langmuir 24(7), 3517-3524 (2008)... 

Stenzel, M.H., Bamer-Kowollik, C., Davis, T.P. Formation of honeycomb-structured, porous films via breath figures with different polymer architectures. J. Polym. Sci. A Polym. Orem. 44(8), 2363-2375 (2006)... 

Heng, L., Wang, B., Li, M., Zhang, Y., Jiang, L. Advances in fabrication matraials of honeycomb structure films by the breath-figure method. Materials 6(2), 460-482 (2013)... 

Most of the above mentioned approaches resort to the use of templates that must be removed after the fabrication of the porous films. These templates are, in general, difficult to prepare or they are rather hard to be removed. This chapter is devoted to an alternative approach, i.e., the breath figures (BF) templating method [5, 25-29]. 

The breath figures technique is one of the most widely employed methods for the fabrication of organized porous polymer films [30, 31] and, as fiuther depicted in detail, in this approach the template consists of an ordered array of water droplets that can be removed by simple evaporation. Indeed, the simultaneous evaporation of a volatile solvent and condensation of water vapor in combination with thermocapillary effects and Marangoni convection allow the formation and precise organization of water droplets at the polymer solution-air interface [30]. This array of water droplets will evaporate upon complete evaporation of the solvent of the polymeric solution, and the surface will reflect its presence in the form of pores. 

A particular case of breath figures formation concerns the use of polymeric solutions as cold surfaces that can produce highly ordered and functional porous materials. Thus, this approach to produce porous films is recognized as breath figures templating method. 

Breath Figures Fabrication of Floneycomb Porous Films Induced... 

Experimental Parameters to Induce Topographical Modifications Using the Breath Figures Approach... 

---