Microphase-separated, hierarchical macroporous polyurethane from a nonaqueous emulsion-templated reactive block copolymer

Abstract

Abstract A series of microphase-separated, hierarchical macroporous polyurethane (PU) polyHIPEs with high-porosity, highly interconnected, open-cell structures have been fabricated from nonaqueous high internal phase emulsions (HIPEs). These paraffin oil-in-dimethyl sulfoxide nonaqueous HIPEs, stabilized by an X-shaped block copolymer (ethylenediamine tetrakis(ethoxylate-block-propoxylate) tetrol, T1107), enabled the fabrication of PU polyHIPEs from the T1107 and isocyanate through step-growth polymerization (SGP). The T1107 serves both as HIPE stabilizer and as monomer. The as-obtained PU polyHIPEs exhibited hierarchical voids in two different scales. One is in ten-micron from emulsion-templating and another is in hundred-micron from CO2, which was generated from the reaction between isocyanate and water. These voids were connected by interconnected holes. Microphase-separation was observed between poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) domains in these PU polyHIPEs. The PU polyHIPEs showed crystalline structures, and their Young’s moduli ranged from 0.3 to 4.4\u202fMPa. These PU polyHIPEs exhibited preferential liquid adsorption. They absorbed a large amount of halogenated liquids, with absorption capacities of 36.0\u202fg·g−1 for chloroform and 27.3\u202fg·g−1 for 1,2-dichloroethane, and with a high absorption rate, which half equilibrium uptakes reached within 2\u202fmin. These PU polyHIPEs are an excellent candidate for preferentially absorbing and removing toxic halogenated liquids.