Emulsion-induced ordered microporous films using amphiphilic poly(ethylene oxide)-block-poly(n-butyl isocyanate) block copolymers

Well-defined poly(ethylene oxide)-block-poly(n-butyl isocyanate) (PEO-block-PBIC; AB) diblock copolymers were prepared with trichloropentadienyl titanium (IV) (CpTiCl₃) catalyst. Ordered microporous films (hexagonal pattern) were constructed by emulsion micelles of A₁₁₀B₂₃₀ diblock copolymer (the subscript indicates the degree of polymerization of each block component) formed from CHCl₃/H₂O/tetrahydrofuran (THF) = 100/5/10 (v/v) solution. The addition of THF promoted uniform micelles in immiscible CHCl₃/H₂O mixed solvent as well as the effect of phase transfer catalyst. Diblock copolymers formed spherical micelles, consisting of a PEO core and a PBIC corona. At some concentration, interaction between micelles forced a disorder-order transition, resulting in freezing of micelles in some superlattice. Subsequently, the leaving gaps among micelles were filled by PBIC block chains on a corona through the evaporation of organic solvents. At last, water within hydrophilic PEO core was vomited through the film matrix. We also constructed the microporous films using A₁₁₀B₂₃₀ diblock copolymer by the current water-assisted method.