- NSF-PAR ID:
- 10229120
- Date Published:
- Journal Name:
- Polymer Chemistry
- Volume:
- 12
- Issue:
- 19
- ISSN:
- 1759-9954
- Page Range / eLocation ID:
- 2840 to 2847
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract ipso ‐Arylative ring‐opening polymerization of 2‐bromo‐8‐aryl‐8H ‐indeno[2,1‐b]thiophen‐8‐ol monomers proceeds to Mnup to 9 kg mol−1with conversion of the monomer diarylcarbinol groups to pendent conjugated aroylphenyl side chains (2‐benzoylphenyl or 2‐(4‐hexylbenzoyl)phenyl), which influence the optical and electronic properties of the resulting polythiophenes. Poly(3‐(2‐(4‐hexylbenzoyl)phenyl)thiophene) was found to have lower frontier orbital energy levels (HOMO/LUMO=−5.9/−4.0 eV) than poly(3‐hexylthiophene) owing to the electron‐withdrawing ability of the aryl ketone side chains. The electron mobility (ca. 2×10−3 cm2 V−1 s−1) for poly(3‐(2‐(4‐hexylbenzoyl)phenyl)thiophene) was found to be significantly higher than the hole mobility (ca. 8×10−6 cm2 V−1 s−1), which suggests such polymers are candidates for n‐type organic semiconductors. Density functional theory calculations suggest that backbone distortion resulting from side‐chain steric interactions could be a key factor influencing charge mobilities. -
Abstract ipso ‐Arylative ring‐opening polymerization of 2‐bromo‐8‐aryl‐8H ‐indeno[2,1‐b]thiophen‐8‐ol monomers proceeds to Mnup to 9 kg mol−1with conversion of the monomer diarylcarbinol groups to pendent conjugated aroylphenyl side chains (2‐benzoylphenyl or 2‐(4‐hexylbenzoyl)phenyl), which influence the optical and electronic properties of the resulting polythiophenes. Poly(3‐(2‐(4‐hexylbenzoyl)phenyl)thiophene) was found to have lower frontier orbital energy levels (HOMO/LUMO=−5.9/−4.0 eV) than poly(3‐hexylthiophene) owing to the electron‐withdrawing ability of the aryl ketone side chains. The electron mobility (ca. 2×10−3 cm2 V−1 s−1) for poly(3‐(2‐(4‐hexylbenzoyl)phenyl)thiophene) was found to be significantly higher than the hole mobility (ca. 8×10−6 cm2 V−1 s−1), which suggests such polymers are candidates for n‐type organic semiconductors. Density functional theory calculations suggest that backbone distortion resulting from side‐chain steric interactions could be a key factor influencing charge mobilities. -
Membrane 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 copolymer additive led to better resistance to fouling by a saline oil-in-water emulsion and to simulated protein adsorption in Atomic Force Microscopy (AFM) force measurements. The additive architecture had a significant influence on how membranes respond to changes in feed salinity, which is known to affect intra- and inter-molecular interactions in zwitterionic polymers. The random copolymer containing membrane showed a small and mostly reversible decrease in its permeance with salinity. In contrast, the comb copolymer-containing membrane underwent a conformational reorganization in saline solutions that leads to an irreversible permeance decrease, increased zwitterionic group content on the membrane surface, and smoother surface topography. The higher mobility of the zwitterionic groups in the comb-shaped architecture facilitates reorganization of the zwitterionic side-chains in response to ionic strength. Overall, this study establishes a new approach for developing highly fouling resistant membranes and defines how the architecture of a zwitterionic copolymer additive impacts the ionic strength response and fouling resistance of the membrane.more » « less
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ABSTRACT Despite the emergence of direct arylation polymerization (DArP) as an alternative method to traditional cross‐coupling routes like Stille polymerization, the exploration of DArP polymers in practical applications like polymer solar cells (PSCs) is limited. DArP polymers tend to have a reputation for being marginally inferior to Stille counterparts due to the increased presence of defects that result from unwanted side reactions in direct arylation, such as unselective C‐H bond activation and homocoupling. We report ten DArP protocols across the three major classes of DArP to generate poly[(2,5‐bis(2‐hexyldecyloxy)phenylene)‐alt‐(4,7‐di(thiophen‐2‐yl)benzo[c][1,2,5]thiadiazole)] (PPDTBT). Through evaluation of the method and resulting photophysical and electronic properties, we show not all DArP methods are suitable for generating device‐quality alternating copolymers. When DArP PPDTBT was synthesized in superheated THF with Cs2CO3, neodecanoic acid, and P(
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We 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, as compared to the cationic homopolymer (HC 50 /MBC < 1). Thus, the systematic tuning of the PEG graft density and chain length effectively enhances the cell-type selectivity of these self-immolative polymers by orders of magnitude.more » « less