It's only partially supported by public money, as far as I can tell. Perhaps the industrial sponsors don't want it to be open access?
Luckily, the paper is accessible through SciHub it seems.
From the paper:
Funding: Financial support from The Dow Chemical Company and DuPont is acknowledged. T.E.C. and E.D.G. acknowledge financial support from the National Science Foundation under awards DMR-1609417 and DMR-1905550. K.P.B., A.L.Z., and E.D.G. also acknowledge support from the Center for Membrane Science, Engineering, and Technology (MAST) and the National Science Foundation under award IIP-1841474. M.K. acknowledges support from the National Science Foundation under award CBET-1946392. B.G. and B.K. are funded in part by the National Science Foundation under award CMMI-1906194. B.G. and B.K. also acknowledge computing support from XSEDE TG-CTS110007
Luckily, the paper is accessible through SciHub it seems.
From the paper:
Funding: Financial support from The Dow Chemical Company and DuPont is acknowledged. T.E.C. and E.D.G. acknowledge financial support from the National Science Foundation under awards DMR-1609417 and DMR-1905550. K.P.B., A.L.Z., and E.D.G. also acknowledge support from the Center for Membrane Science, Engineering, and Technology (MAST) and the National Science Foundation under award IIP-1841474. M.K. acknowledges support from the National Science Foundation under award CBET-1946392. B.G. and B.K. are funded in part by the National Science Foundation under award CMMI-1906194. B.G. and B.K. also acknowledge computing support from XSEDE TG-CTS110007