Behaviour of cationic polyelectrolytes upon binding of electrolytes: effects of polycation structure, counterions and nature of the solvent

Ghimici, Luminiţa; Drăgan, Ecaterina Stela

doi:10.1007/s003960100575

Cited by 43 publications

(39 citation statements)

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“…38,39 An alternative explanation of the effect of salt on solubility of a neutral polymer can be suggested, as the salt effect on the lower critical solution temperature (LCST) of PNIPAM 40,41 and PVCL 42 also follows the anion Hofmeister series, 43,44 with kosmotropic anions decreasing the LCST. [40][41][42] Specifically, I -was found to increase the solubility and raise the LCST of PVCL solutions, so as Brat concentrations lower than 0.3 mg/mL.…”

Section: Resultsmentioning

confidence: 98%

Hydrogen-Bonded Multilayers of Poly(carboxybetaine)s

2007

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Using a layer-by-layer (LbL) sequential adsorption technique, we studied the construction of hydrogen-bonded multilayers of a weak polycarboxybetaine (poly-N-ω-carboxypentyl-4-vinylpyridinium bromide (PCB5)) with poly(N-vinylcaprolactam) (PVCL). Self-assembly occurred at low pH values where carboxylic groups of PCB5 units were protonated and capable of binding with hydrogen-accepting groups of PVCL. Multilayers could not be constructed, however, in 0.01 M buffer solutions at pH 2.5, and potassium halide salts were required to promote multilayer deposition. Concentrations of halide salts at which deposition of PCB5/ PVCL multilayers occurred decreased in the series KCl > KBr > KI, following the Hofmeister series for binding of anions with PCB5 chains. Using a N-vinylcaprolactam copolymer which contained amino groups (PVCL-NH 2 ), PCB5/PVCL-NH 2 multilayers were constructed and covalently cross-linked, producing surface-attached hydrogels. The hydrogels showed typical polyelectrolyte salt-induced contraction at pH 2.5, where PCB5 units were cationic, but "antipolyelectrolyte" behavior, i.e., swelling in salt solutions at pH 7.5, where PCB5 units were zwitterionic. PCB5/PVCL-NH 2 surface hydrogels were resistant to adsorption of negatively charged proteins and heparin at pH 7.4 in 0.15 M NaCl solutions. The produced PCB5/PVCL films and cross-linked PCB5/ PVCL-NH 2 surface hydrogels might find applications as erasable films or as zwitterion-containing bioinert coatings, respectively.

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Section: Resultsmentioning

confidence: 98%

Hydrogen-Bonded Multilayers of Poly(carboxybetaine)s

2007

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“…Specifically, multiply charged sulfate anions had weak binding at the Ag [+] surface despite their higher charge than other anions studied. Rather, the anion binding order follows the Hofmeister series, 45,46 which is usually found for specific binding of anionic counterions with synthetic polycations, synthetic proteins, or amide group containing water-soluble polymers. 47,48 This order reflects stronger condensation of "chaotropic", less hydrated anions on the Ag [+] nanoparticle surface, as compared to "kosmotropic", more hydrated anions.…”

Section: Comparative Sers Study Of Binding Of Variousmentioning

confidence: 99%

Substrates with Discretely Immobilized Silver Nanoparticles for Ultrasensitive Detection of Anions in Water Using Surface-Enhanced Raman Scattering

et al. 2008

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Positively charged silver nanoparticles, Ag [+], obtained by UV-assisted reduction of silver nitrate using branched poly(ethyleneimine) (BPEI) and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) solutions as reducing agents, were immobilized on glass surfaces to produce substrates active in surface-enhanced Raman scattering (SERS). Negatively charged silver nanoparticles, Ag [-], synthesized via a modified citrate reduction method, were also investigated for comparison. At a sparse surface coverage of 30 nanoparticles/microm(2), substrates with immobilized Ag [+] showed increasing SERS sensitivity to a variety of anions in water in the order SO(4)(2-) < CN(-) < SCN(-) approximately ClO(4)(-), with corresponding binding constants of 10(5), 3.3 x 10(5), and 10(7) (for both SCN- and ClO(4)(-)) M(-1), respectively. This order followed the Hofmeister series of anion binding in water. Significantly, substrates with Ag [+] allowed limit of detection values of 8.0 x 10(-8) M (8 ppb) and 2.7 x 10(-7) M (7 ppb) for environmentally relevant perchlorate (ClO(4)(-)) and cyanide (CN(-)) anions, respectively. In contrast, substrates with immobilized Ag [-], even upon subsequent modification by a monolayer of BPEI for positive surface charge of the nanoparticles, showed a drastically lower sensitivity to these anions. The high sensitivity of substrates with Ag [+] for anion detection can be attributed to the presence of two types of functional groups, amino and amide, on the nanoparticle surface resulting from UV-assisted fragmentation of BPEI chains. Both amino and amide provide strong binding of anions with Ag [+] nanoparticles due to the synergistic effect through a combination of electrostatic, hydrogen bonding, and dispersive interactions.

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“…These interactions are strongly sensitive to some parameters such as the chain length, the charge density, the polyelectrolyte concentration, the counterion type, the ionic strength, the solvent polarity, etc. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Perhaps the most significant parameter affecting the solution properties of a polyelectrolyte is the linear charge density whose importance has been promoted by Manning in his counterion condensation theory [24,25].…”

Section: Introductionmentioning

confidence: 99%