Abstract
The stability of fluoro-high internal phase emulsion (fluoro-HIPE) systems and fluoro-polyHIPEs’ mechanical strength require further improvement to meet the requirements of future applications. In this study, we used polylactic acid (PLA) as a co-stabilizer to improve the stability of the fluoro-polyHIPE. The effects of concentration and molecular weight of PLA on the pores of the fluoro-polyHIPEs were investigated. The addition of PLA produced a porous material with narrower void size distributions, higher specific surface areas and enhanced mechanical properties compared to the fluoro-polyHIPE material without the additive. The resulting fluoro-polyHIPE showed smaller pore sizes (void diameters ranged from 1–3 μm) and an improved hydrophobic nature (contact angle can reach to 148.6°). The crush strength and Young's modulus values can reach 4.42 and 74.07 MPa, respectively, at a PLA addition of 25 wt% (oil phase composition), representing increases of 246% and 650% over fluoro-polyHIPE without PLA addition. The fluoro-poly-HIPE demonstrated excellent mechanical properties compared to many engineering foams, such as melamine, polystyrene, and even graphite foams. Improvements in the performance of porous fluoropolymer materials will be beneficial for many applications, such as chemical adsorption and separation, etc.
Highlights
Porous polymer foams or monoliths play an important role in a wide range of applications such as rapid oil/water separation,[1] supporting materials for growth of tissues,[2] catalyst attachment,[3] controlled release matrices,[4] separation membranes,[5] heavy metal ion collectors,[6] as well as other uses.[7]
The addition of polylactic acid (PLA) produced a porous material with narrower void size distributions, higher specific surface areas and enhanced mechanical properties compared to the fluoro-polyHIPE material without the additive
Barbetta et al reported that pore size could be adjusted by changing the monomer type; polyHIPEs prepared from 4-vinylbenzyl chloride (VBC) and divinylbenzene (DVB) had smaller average void diameters than those prepared from styrene and divinyl benzene (DVB) and the pore size could be reduced to 5 mm by regulating the VBC content.[27]
Summary
Porous polymer foams or monoliths play an important role in a wide range of applications such as rapid oil/water separation,[1] supporting materials for growth of tissues,[2] catalyst attachment,[3] controlled release matrices,[4] separation membranes,[5] heavy metal ion collectors,[6] as well as other uses.[7]. Barbetta et al reported that pore size could be adjusted by changing the monomer type; polyHIPEs prepared from 4-vinylbenzyl chloride (VBC) and divinylbenzene (DVB) had smaller average void diameters than those prepared from styrene and DVB and the pore size could be reduced to 5 mm by regulating the VBC content.[27] Zhu et al stated the effect of temperature on either stability of HIPEtemplates or morphologies of the corresponding polyHIPEs.[23] Zhang reported that the internal phase volume fraction affected the pore size; the pore size could be reduced to 33 mm by decreasing the internal phase volume at the expense of porosity.[28] Cameron found that pore size could be reduced from 15 to 5 mm by changing the amount of DVB crosslinking agent the subsequent increase in DVB weakened the performance of the host monomer.[29] Zhang et al and Chen et al both reported that increasing the concentration of an aqueous solution of NaCl gave a 10 fold reduction in void diameter (from circa 30–50 mm) in the resulting polymer.[30] the latter method had only a small effect on the pore size and was less effective in the uorinated emulsion Hydrodynamic effects, such as viscosity of the continuous phase and interfacial tension are important factors determining droplet coalescence and emulsion stability. This type of porous uorinated-foams has excellent oleophilicity and hydrophobicity, with water contact angles (WCA) up to 148.4 (nearly superhydrophobic) and possessed enhanced mechanical properties
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