Facile preparation of hierarchically porous polymer microspheres for superhydrophobic coating

Abstract

A facile method, i.e., nonsolvent assisted electrospraying, is proposed to fabricate hierarchically porous microspheres. The pore size on the microsphere surface ranges from a few tens to several hundred nanometers. Thermally and nonsolvent induced phase separation as well as breath figure is responsible for the formation of the hierarchical structures with different nano-sized pores. The nonsolvent could not only induce phase separation, but also stabilize the interface between the droplet and air, which can prevent the droplet from strong deformation, and is therefore beneficial to the formation of regular and uniform microspheres. On the other hand, solvent evaporation, polymer diffusion and Coulomb fission during electrospraying influence the morphology of finally obtained products. In this paper, the influence of polymer concentration, the weight ratio between nonsolvent and polymer and the flowing rate on the morphology of the porous microsphere is carefully studied. The hierarchically porous microsphere significantly increases the surface roughness and thus the hydrophobicity, and the contact angle can reach as high as 152.2 ± 1.2°. This nonsolvent assisted electrospraying opens a new way to fabricate superhydrophobic coating materials.

Integrated process for preparing porous, surface functionalized polyetherimide microparticles

“…porogen‐based methods, spraying methods or phase separation methods) have been employed for preparation of porous microparticles with controlled pore sizes and morphologies . Examples are poly( ε ‐caprolactone) based microparticles with aligned pores prepared by an emulsion freezing approach, hierarchically structured poly(methyl methacrylate) particles prepared via non‐solvent assisted electrospraying or highly porous poly(ether imide) (PEI) microparticles where the internal pore structure can be altered by variation of the solvent applied in the spraying/coagulation process . Nanoporous PEI particles are discussed as candidate absorber materials for apheresis applications e.g.…”

Poly(α-hydroxy Acids)-Based Cell Microcarriers

“…Polymer concentration, flow rate and applied voltage are commonly modulated to control the size of the resulting particles [70]. Electrospraying represents a completely different approach for the fabrication of microcarriers made out of biodegradable poly(α-hydroxyacids), and has received less attention than the aforementioned methods, probably due to the need for more complex equipment for its implementation [69][70][71]. In this technique, a polymer solution is loaded into a syringe that flows at a constant rate along a highly charged needle.…”

Synthesis of superhydrophobic fluorinated polystyrene microspheres via distillation precipitation polymerization

“…Polymer microsphere with spherical shape and smooth surface has attracted great attention owing to its potential applications in many fields, such as photonic crystals [15], gas sensing [16], and preparation of superhydrophobic surface [17,18]. The fluorinated interfaces have been prepared by the postmodification of surface chemistry for the resultant close packed lattice via nanosphere lithography [19][20][21] or layer by layer deposition over the ordered arrays of particles [22][23][24].…”