Breath figure method

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)... 

Kim and coworkers reported the application of breath figure method to a small photo-responsive molecule, i.e., a organogelator self-assembled into supramolecu-lar fibrillar networks and further ordered in a hierarchically honeycomb structure [194]. Recently, a new organogelator was synthesized and large-scale ordered honeycomb patterns were also observed [195]. Moreover, Babu et al. also reported the formation of hierarchical macroporous structures from an amino acid linked p-conjugated organogelator [196]. 

Microporous membranes are often used in many processes to remove impurities or contaminants through size-selective filtration. The breath figures method also finds application in this field, specially the approaches that facilitate the easy transfer to other supports. Another prerequisite is the formation of through pores that penetrate from the top of the layer to the bottom and the use of ice support favors this fact. For example, highly uniform membranes of PS-h-PDMAEMA have been prepared with pores on the micrometer scale for size-selective separation. The films were prepared by casting at an air-ice interface and easily transferred onto other supports [219]. Miktoarm star copolymers with proper water wettability and mechanical stability have been used to fabricate separation membranes also using ice substrate [131]. Moreover, the breath figures approach has been employed to build polymer membranes on structured substrates in order to obtain hierarchically structured microsieves [208]. 

Li, J., Zhao, Q.L., Chen, J.Z., Li, L., Huang, J., Ma, Z., et al. Highly ordered microporous films containing a polyolefin segment fabricated by the breath-figure method using well-defined polymethylene-b-polystyrene copolymers. Polym. Chem 1, 164—167 (2010)... 

Cong, H.L., Wang, J.L., Yu, B., Tang, J.G. Preparation of a highly permeable ordered porous microfiltration membrane of brominated poly(phenylene oxide) on an ice substrate by the breath figure method. Soft Matter 8, 8835-8839 (2012)... 

Lin, C.L., Tung, P.H., Chang, F.C. Synthesis of rod-coil diblock copolymers by ATRP and their honeycomb morphologies formed by the breath figures method. Polymer 46, 9304-9313 (2005)... 

Sun, W., Shao, Z., Ji, J.A. Particle-assisted fabrication of honeycomb-structured hybrid films via breath figures method. Polymer 51,4169 175 (2010)... 

FIGURE 6.15 Array formation utilizing the breath-figure method. (Courtesy Prof Srinivasarao.)... 

Englert, B.C., et al. 2005. Templated ceramic microstructures by using the breath-figure method. Chem Eur /11 995. 

Figure 6(A) is an illustration of a superhydrophobic, self-assembled silica microsphere film reported by Sun et al. (2007). Figure 6(B) is a 3D atomic force microscopy image of hierarchically ordered microporous polymer formed by spontaneous assembly of water vapor condensation, so-called breath figure method (Zander et al., 2007). Tsai and Lee (2007) reported a raspberry-like structure of superhydrophobic films by assembling one...

When astronauts travel in a space shuttle (Figure 12.17), carbon dioxide must be removed from the air they breathe. One method is to bubble the air in the shuttle though a solution of lithium hydroxide. The lithium hydroxide converts any carbon dioxide into lithium carbonate. 

Figure 4. Equation of state for silicate perovskites. a) Both VIB and MPIB models give a good account of the compressibility and density of CaSiO 3 perovskite, which i s predicted to be cubic, in accord with data, b) Calculated MgSiO 3 equations of state compared with data. The MEG calculation [66] used rigid ions it gave poor absolute densities but excellent compressibility and thermal expansivity. The breathing ion methods (MPIB and PIB) fare much better. R H and K J stand for Ross and Hazen [67] and Knittle and Jenaloz [68], respectively. LAPW calculation from Stixrude and Cohen [23].

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 figure process is a simple and robust method based on the fast endothermic solvent evaporation upon casting a polymer solution under humid atmosphere. The water condensation occurring on the top surface produces an ordered array of hexagonally packed water droplets. The surface of the final polymer film is structured by a hexagonal array of pores which are structured into either mono- or three-dimensional structure. Observation of the cross section of honeycomb films shows that pores can be connected in the longitudinal direction [113-115] (Fig. 10.5). 

Besides the control of the surface topography, the breath figures approach offers the possibility to control the chemical functionality within the patterned film directed by the formation mechanism. The versatility of the method enables the preparation of... 

Bimz, U.H.F. Breath figures as a dynamic templating method for polymers and nanomaterials. Adv. Mater. 18, 973-989 (2006)... 

Xiong, X.P., Lin, M.F., Zou, W.W., Liu, X.Y. Kinetic control of preparing honeycomb patterned porous film by the method of breath figure. React. Punch Poljrm. 71, %4-971... 

Water vapor condenses onto the polymer films Water condensation during film formation leads to the formation of ordered water droplet arrays on surfaces. This is a well-known phenomenon named breath figures (BFs) because of their formation by breathing on cold surfaces [59-63]. A particular case of BF formation is the use of a polymeric solution that, under appropriate conditions, can produce highly ordered porous materials (ie, BF templat-ing method). 

The breath figures approach, i.e., the water condensation during film formation, provides an interesting alternative to the modification of both the chemical distribution of the functional groups at the surface and the topography [1,226-230]. This method has been successfully employed to create honeycomb patterns with potential for cell scaffold appUcations among others [231] or to create carbohydrate nticroarrays [232]. Whereas most of the studies have been carried out using homopolymers or copolymers, several... 

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