title: Morphology and Proton Transport in Humidified Phosphonated Peptoid Block Copolymers.
abstract: Polymers that conduct protons in the hydrated state are of crucial importance in a wide variety of clean energy applications such as hydrogen fuel cells and artificial photosynthesis. Phosphonated and sulfonated polymers are known to conduct protons at low water content. In this paper, we report on the synthesis phosphonated peptoid diblock copolymers, poly-N-(2-ethyl)hexylglycine-block-poly-N-phosphonomethylglycine (pNeh-b-pNpm), with volume fractions of pNpm (ϕNpm) values ranging from 0.13 to 0.44 and dispersity (Đ) ≤ 1.0003. The morphologies of the dry block copolypeptoids were determined by transmission electron microscopy and in both the dry and hydrated states by synchrotron small-angle X-ray scattering. Dry samples with ϕNpm> 0.13 exhibited a lamellar morphology. Upon hydration, the lowest molecular weight sample transitioned to a hexagonally packed cylinder morphology, while the others maintained their dry morphologies. Water uptake of all of the ordered samples was 8.1 ± 1.1 water molecules per phosphonate group. In spite of this, the proton conductivity of the ordered pNeh-b-pNpm copolymers ranged from 0.002 to 0.008 S/cm. We demonstrate that proton conductivity is maximized in high molecular weight, symmetric pNeh-b-pNpm copolymers.
authors.affiliation: Molecular Foundry, Materials Sciences Division, Molecular Biophysics and Integrated Bioimaging Division, Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States; School of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao, China 266042.
authors.forename: Jing
authors.initials: J
authors.lastname: Sun
authors.affiliation: Molecular Foundry, Materials Sciences Division, Molecular Biophysics and Integrated Bioimaging Division, Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Xi
authors.initials: X
authors.lastname: Jiang
authors.affiliation: Department of Medicinal Chemistry, Amgen Inc. , One Amgen Center Drive, Thousand Oaks, California 91320-1799, United States.
authors.forename: Aaron
authors.initials: A
authors.lastname: Siegmund
authors.affiliation: Molecular Foundry, Materials Sciences Division, Molecular Biophysics and Integrated Bioimaging Division, Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States; Molecular Foundry, Materials Sciences Division, Molecular Biophysics and Integrated Bioimaging Division, Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Connolly
authors.affiliation: Molecular Foundry, Materials Sciences Division, Molecular Biophysics and Integrated Bioimaging Division, Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Kenneth H
authors.initials: KH
authors.lastname: Downing
authors.affiliation: Molecular Foundry, Materials Sciences Division, Molecular Biophysics and Integrated Bioimaging Division, Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States; Molecular Foundry, Materials Sciences Division, Molecular Biophysics and Integrated Bioimaging Division, Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States; Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, United States.
authors.forename: Nitash P
authors.initials: NP
authors.lastname: Balsara
authors.affiliation: Molecular Foundry, Materials Sciences Division, Molecular Biophysics and Integrated Bioimaging Division, Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States; Molecular Foundry, Materials Sciences Division, Molecular Biophysics and Integrated Bioimaging Division, Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
authors.forename: Ronald N
authors.initials: RN
authors.lastname: Zuckermann