- Publication Date:
- NSF-PAR ID:
- Journal Name:
- Polymer Chemistry
- Page Range or eLocation-ID:
- 2840 to 2847
- Sponsoring Org:
- National Science Foundation
More Like this
Zwitterionic copolymer additive architecture affects membrane performance: fouling resistance and surface rearrangement in saline solutionsMembrane separations are simple to operate, scalable, versatile, and energy efficient, but their broader use is curtailed by fouling or performance decline due to feed component depositing on the membrane surface. Surface functionalization with groups such as zwitterions can mitigate the adsorption of organic compounds, thus limiting fouling. This can be achieved by using surface-segregating copolymer additives during membrane manufacture, but there is a need for better understanding of how the polymer structure and architecture affect the effectiveness of these additives in improving membrane performance. In this study, we aim to explore the impact of the architecture of zwitterionic copolymer additives for polyvinylidene fluoride (PVDF)-based membranes in fouling mitigation and ionic strength response. We prepared membranes from blends of PVDF with zwitterionic (ZI) copolymers with two different architectures, random and comb-shaped. As the random copolymer, we used poly(methyl methacrylate- random- sulfobetaine-2-vinyl pyridine) (PMMA- r -SB2VP) synthesized by free radical polymerization. The comb-shaped copolymer was synthesized by grafting SB2VP side-chains from a PVDF backbone by controlled radical polymerization. Membranes were fabricated from PVDF-copolymer blends containing up to 5 wt% ZI copolymer. Compared to the additive-free PVDF membrane, water permeance increased five-fold with 5 wt% addition of either copolymer. The comb copolymermore »
Self-immolative polymers with potent and selective antibacterial activity by hydrophilic side chain graftingWe report the first example of a self-immolative polymer that exerts potent antibacterial activity combined with relatively low hemolytic toxicity. In particular, self-immolative poly(benzyl ether)s bearing pendant cationic ammonium groups and grafted poly(ethylene glycol) chains in their side chains were prepared via post-polymerization thiol–ene chemistry. These functional polymers undergo sensitive and specific triggered depolymerization into small molecules upon exposure to a designed stimulus (in this example, fluoride ions cleave a silyl ether end cap). The molar composition of the resulting statistical copolymers varied from 0 to 100% PEG side chains. The average molar mass of the pendant PEG chains was either 800 or 2000 g mol −1 . The antibacterial and hemolytic activities were evaluated as a function of copolymer composition. Strong bactericidal activity (low μg mL −1 MBC) was retained in the copolymers containing 25–50% PEG-800, whereas hemolytic toxicity monotonically decreased (up to HC 50 >1000 μg mL −1 ) with increasing PEG content. PEG-2000 was far less effective; both the MBC and HC 50 decreased to a comparable extent with increasing PEGylation. Overall, the best cell type selectivity index (HC 50 /MBC ∼ 28) was obtained for the copolymer containing ∼50% cysteamine and ∼50% PEG-800 side chains, asmore »
Oxygen-bearing functionalities enhancing NO 2 , NH 3 , and acetone electronic response and response variation by polythiophenes in organic field-effect transistor sensorsWe investigated the enhanced vapor responses and altered response ratios of a series of thiophene (co)polymers with oxygenated side chains (CH 2 OH, linear polyethylene glycol, and crown ether), including the novel poly(3-hydroxymethylthiophene) (PTOH) and other newly synthesized polymers. Hydroxymethyl-containing copolymers had higher mobility compared to poly(3-hexylthiophene) (P3HT). The larger crown ether moiety promotes transistor characteristics of P3HT while the smaller one impairs them. Incorporating different oxygen bearing functionalities increased responses of thiophene polymers to NO 2 , NH 3 , and acetone. For example a polyether side chain increases the NO 2 response sensitivity of copolymers of both P3HT and PTOH, but sensitivity towards gas analytes was more prominent for glycol-based functionalities rather than the crown ethers. PTOH is very sensitive to NO 2 and the response likely includes a contribution from conductive protons on the OH group. The lack of correlation among the rank-ordered gas sensitivities imparted by each functional group was found to be useful for designing a selective sensor array. We specifically showed high classification accuracy for all the polymer responses to NO 2 and acetone vapors, both of which gave increased device currents but with response ratios different enough to allow highly classifying discriminant functionsmore »
A p-π* conjugated triarylborane as an alcohol-processable n-type semiconductor for organic optoelectronic devicesWe report a p-π* conjugated organic molecule based on triarylborane as n-type organic semiconductor with unique alcohol solubility. Its favorable alcohol solubility even in the absence of polar side chains is mainly due to the large dipole moment and enhanced flexibility of the conjugated backbone once the boron atom is embedded. The p-π* conjugation directly affects the electronic structure as the LUMO is fully delocalized, including the boron atom, whereas the HOMO has the boron atom residing on a node. As a result, the molecule exhibits low-lying LUMO/HOMO energy levels of −3.61 eV/−5.73 eV paired with a good electron mobility of 1.37 × 10 −5 cm 2 V −1 s −1 . We further demonstrate its application as an electron acceptor in alcohol-processed organic solar cells (OSCs). To our best knowledge, this p-π* conjugated molecule is the first alcohol-processable non-fullerene electron acceptor, a feature that is in strong demand for environmentally friendly processing of OSCs.
In this paper a photovoltaic system is proposed that achieves high energy yield by integrating bifacial silicon cells into a spectrum-splitting module. Spectrum splitting is accomplished using volume holographic optical elements to spectrally divide sunlight onto an array of photovoltaic cells with different bandgap energies. Light that is reflected from the ground surface onto the rear side of the module is converted by the bifacial silicon cells. The energy yield of the system is optimized by tuning the volume holographic element parameters, such as film thickness, index modulation, and construction point source positions. An example is presented for utility-scale illumination parameters in Tucson, Arizona, that attains an energy yield of
, which is 32.8% of the incident solar insolation.