Influence of Bound Ion on the Morphology and Conductivity of Anion-Conducting Block Copolymers

Abstract

Polystyrene-block-polychloromethylstyrene (PS-b-PCMS) copolymers, with molecular weights ranging from 4 to 60 kg/mol, were synthesized by nitroxidemediated controlled radical polymerization. Separate aliquots of the PS-b-PCMS samples were quaternized to transform the PCMS block. This resulted in block copolymers with ionizable blocks containing either trimethylammonium chloride or nbutylimidazolium chloride. We refer to ion-containing block copolymers synthesized from the same precursor as matched pairs: SAM (containing trimethylammonium chloride) and SIM (containing n-butylimidazolium chloride). The volume fraction of the ion-containing block, φ, ranges from 0.26 to 0.50 for the case of SAM and from 0.35 to 0.60 for the case of SIM. Self-assembly in these copolymers resulted in the formation of lamellar phases regardless of φ, chemical formula of the bound ion, and chain length. Chloride ion conductivity and water uptake measurements on one of the matched pairs led to similar results. In this matched pair, the changes in conductivity are reported as the chloride ions are replaced by hydroxide ions.

Reactive Oxygen Species Function to Mediate the Fe Deficiency Response in an Fe-Efficient Apple Genotype: An Early Response Mechanism for Enhancing Reactive Oxygen Production

“…Some studies support the involvement of H 2 O 2 in the regulation of ferritins in response to excess Fe to prevent oxidative stress (Ravet et al, 2009, 2012; Briat et al, 2010; Sudre et al, 2013; Reyt et al, 2015), but how ROS participate in that regulation of Fe deficiency stress in woody plants remained unknown. Previous research has proposed that H 2 O 2 can be considered an intermediate in the auto-regulatory suppression of FIT after prolonged Fe deficiency in Arabidopsis thaliana (Le et al, 2016).…”

“…In addition, GSH and ASC levels were increased in cucumber and sugar beet exposed to conditions of Fe deficiency (Zaharieva et al, 1999; Zaharieva and Abadìa, 2003). H 2 O 2 is involved in the regulation of ferritins in response to excess Fe to alleviate oxidative stress in leaves (Ravet et al, 2009; Briat et al, 2010), flowers (Sudre et al, 2013), and roots (Ravet et al, 2012; Reyt et al, 2015). ROS production has also been demonstrated under Fe deficiency in sunflower and maize (Ranieri et al, 2001; Sun et al, 2007).…”

Achieving Continuous Anion Transport Domains Using Block Copolymers Containing Phosphonium Cations

“…38 In ammonium ion containing block copolymers with low-T g hydrophobic blocks, Cl − conductivities were reported as high as 5 and 13 mS/cm at 30°C, with the IECs being 2.0 and 2.4 mmol/g, respectively. 57, 58 In the high-T g PS-based materials, both imidazolium and ammonium block copolymers (IEC ≈ 2.4 mmol/g) showed similar Cl − conductivities of ∼15 mS/cm at 70°C, 65 while a cyclopropenium polymer (IEC = 1.3 mmol/g) had a conductivity of 4 mS/cm at room temperature. 68 Using the same setup in this work, an optimized blend of poly(phenylene oxide) and ammonium-based polystyrene block copolymer (IEC = 1.3 mmol/g) was previously reported with a chloride conductivity of 18 mS/cm at 60°C, 98 which was in good agreement with other literature results.…”

Polysulfones with highly localized imidazolium groups for anion exchange membranes

“…Ionic clusters in AEMs have recently been observed in AEMs where QA groups have been concentrated to specific chain segments in the backbone polymer [13,14], attached to short side chains in statistical copolymers [15,16], and when utilizing QA groups with long alkyl chains [17] to facilitate phase separation. A further strategy to promote phase separation is to prepare hydrophilic-hydrophobic multiblock copolymers in which blocks highly functionalized with ionic groups are combined with hydrophobic non-ionic ones [18,19]. Although requiring complex synthetic procedures, these copolymers can be tailored to form percolating hydrophilic phase domains.…”