‘…we are confident that our methods are scalable, both for polymer synthesis and for the production of the membrane.’
Polymer scientists from the University of Groningen and NHL Stenden University of Applied Sciences, both in the Netherlands, have developed a polymer membrane from bio-based malic acid that can be used to separate water and oil.
The fully recyclable membrane can be depolymerised, cleaned and subsequently pressed into a new membrane when the pores become fouled. The work has been published in the journal Advanced Materials.
The material is a superamphiphilic vitrimer epoxy resin; which attracts both oil and water while also having the mechanical properties and chemical resistance of a thermoset plastic. Vitrimer plastics can also behave like a thermoplastic in that they can be depolymerised and reused. ‘This means that a vitrimer plastic has all the qualities to make a good membrane for oil spill remediation, and it is made from malic acid, a natural monomer,’ the researchers said.
The researchers explain that the polymers in the vitrimer are crosslinked in a reversible manner, forming a dynamic network which enables recycling of the membrane. The vitrimer is produced through a base-catalysed ring-opening polymerisation between pristine and epoxy-modified bio-based malic acid. The polymers are ground into a powder by ball milling and then sintering is used to create a porous membrane.
Both water and oil will spread out on the resulting superamphiphilic membrane. In an oil spill the membrane is covered by water which passes through the pores. The water film on the membrane’s surface, keeps the oil out of the pores, thus separating the oil and water. In addition, when sand and algae clog up the pores, the membrane can be depolymerised and recreated from its building blocks.
‘We have tested this on a laboratory scale of a few squarer centimetres, and we are confident that our methods are scalable, both for polymer synthesis and for the production of the membrane,’ said Katja Loos, from the University of Groningen. The research team is hoping that an industrial partner will take up further development.