One-step Ziegler-Natta polymerization of 4-methylpent-1-ene with pentafluorostyrene – A solution processable copolymer with super hydrophobic properties

Abstract

Hydrophobic polymers are of high interest in modern membrane applications ranging from blood oxygenation devices to gas diffusion layers in fuel cells. Poly(4-methyl-1-pentene) (PMP) is an interesting membrane material because of its chemical resistance, paired with low density, hydrophobicity, optical transparency, and excellent gas diffusion characteristics. However, the current method of producing PMP membranes through melt processing is not ideal. A more suitable method would be phase inversion via immersion precipitation, but the low solubility of PMP prevents this process. To overcome this processing problem, we propose creating a copolymer of PMP and a fluorinated polymer, which would offer improved solubility and increased hydrophobicity without loss of gas permeability. We successfully synthesize such a copolymer using Ziegler-Natta polymerization of 4-methyl-1-pentene (4 MP) and pentafluorostyrene (PFS). The resulting copolymer exhibits good solubility in a variety of solvents and a critical surface tension γc of 25 mN/m, enabling electrospinning into non-wovens with superhydrophobic properties.