Segmental Dynamics of Poly(acrylic acid) in Polyelectrolyte Complex Coacervates Studied by Spin-Label EPR Spectroscopy

Lappan, Uwe; Wiesner, Brigitte; Scheler, Ulrich

doi:10.1021/acs.macromol.6b01863

Cited by 28 publications

(21 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the cases in which self-consistent variable temperature experiments have been demonstrated, they have revealed Arrhenius-like dependences on temperature (4,5,32,33). Although this observation lacks a precise formal justification, it is consistent with the widely accepted belief that the motion of spin labels is connected to the diffusion of the label's parent molecule, as well as to the local viscosity of the environment.…”

Section: Introductionsupporting

confidence: 72%

A Global Minimization Toolkit for Batch-Fitting and χ2 Cluster Analysis of CW-EPR Spectra

Lindemann

Christoff‐Tempesta

Ortony

2020

Biophysical Journal

View full text Add to dashboard Cite

Section: Introductionsupporting

confidence: 72%

A Global Minimization Toolkit for Batch-Fitting and χ2 Cluster Analysis of CW-EPR Spectra

Lindemann

Christoff‐Tempesta

Ortony

2020

Biophysical Journal

View full text Add to dashboard Cite

“…On the other hand, several studies have reported that PAA-based complexes prepared under acidic conditions exhibit high salt resistances. ,, For example, Larson and co-workers pointed out that despite the p K a of PAA being ∼5–5.5 and of PAH being ∼8.5–9.3, the salt concentrations required to induce morphological transitions from precipitate to coacervate and from coacervate to solution were markedly asymmetric around pH 7 in PAA (and potassium salt of PAA)–PAH complexes, and critical KCl concentrations >3 M were required to completely dissolve the complexes; both these observations could not be explained solely by electrostatic interactions . Lappan et al reported significantly slower dynamics of PAA chains in complexes prepared under acidic conditions, suggesting stronger association of the polymer network under low pH conditions. Thus, a comprehensive study of the phase behavior of PAA–PAH under various pH conditions is required to address the inconsistencies in PAA–PAH phase behavior.…”

mentioning

confidence: 99%

Effects of Non-Electrostatic Intermolecular Interactions on the Phase Behavior of pH-Sensitive Polyelectrolyte Complexes

et al. 2020

View full text Add to dashboard Cite

Polyelectrolyte complexes (PECs) offer enormous material tunability and desirable functionalities, and consequently have found broad utility in biomedical and materials industries. Poly(acrylic acid) (PAA) and poly(allylamine hydrochloride) (PAH) are one of the most commonly used pairings to form PECs. However, various aspects of the phase behavior of PAA-PAH complexes have not been sufficiently quantified. We present a comprehensive experimental study depicting the binodal phase boundaries for the PAA-PAH complexes prepared in acidic, neutral and basic conditions using thermogravimetric analysis, turbidimetry and optical microscopy. In neutral and basic conditions, phase behaviors of the complexes were largely similar to each other and followed general expectations of PEC phase behavior, except for unusually high salt resistance with stable complexes observed up to 4 M NaCl concentrations. In acidic conditions, a remarkably different phase behavior of the PAA-PAH complexes was observed. The polymer content in the complex phase increased initially followed by an expected decrease as salt was added to the complexes. This behavior may result from a combination of associative phase separation of PAA and PAH chains, influenced by electrostatic interactions, and segregative phase separation which can be ascribed to the influence of a combination of the hydrophobic interactions of the aliphatic polymer backbone and the interpolymer hydrogen bonding of un-ionized acrylic monomer units. Our systematic investigations detailing these discrepancies in the PAA-PAH phase behavior are expected to clarify the inconsistencies among the reports in the literature and inform the materials design strategies for practical use of the PAA-PAH complexes and multilayer assemblies. File list (2) download file view on ChemRxiv Lu_PAAPAH_Phasebehavior_V2.pdf (3.98 MiB) download file view on ChemRxiv SI_Lu_PAAPAH_Phasebehavior_submitted.pdf (1.33 MiB)

show abstract

“…An increase of the rotational mobility with increasing pH was also observed in previous studies about the dynamics in PECs of PDADMAC and SL‐P(E‐ alt ‐MA) as well as spin‐labeled poly(acrylic acid) (SL‐PAA). [ 12,13 ] In these studies only mixtures with ratio of n PC /(2 n PA ) = 1.5 were investigated. The low rotational mobility of the SL at low pH has been assumed to be a consequence of hydrogen bonds between polyacid chains as well as weak hydration of the non‐dissociated polyacid repeat units.…”

Section: Resultsmentioning

confidence: 99%

“…The low rotational mobility of the SL at low pH has been assumed to be a consequence of hydrogen bonds between polyacid chains as well as weak hydration of the non‐dissociated polyacid repeat units. [ 13 ] P(E‐ alt ‐MA) is a weak polyacid with two dissociation constants of p K 0 1 = 3.8 and p K 0 2 = 6.1, [ 18 ] i.e., the degree of dissociation α D is about 0.3 at pH 4 and about 0.5 at pH 5. At pH 4, the PECs are assumed to be stabilized by hydrogen bonds, because about 70% of the COOH groups are nondissociated.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Influence of the Mixing Ratio on the Dynamics of Polymer Segments in Polyelectrolyte Complexes

Lappan

Naas

Scheler

2021

Macro Chemistry & Physics

Self Cite

View full text Add to dashboard Cite

The rotational dynamics of the spin‐labeled polyacid poly(ethylene‐alt‐maleic acid) (P(E‐alt‐MA)) in polyelectrolyte complexes (PECs) formed with the polycations poly(allylamine hydrochloride) (PAH) and poly(diallyldimethylammonium chloride) (PDADMAC) are studied by electron paramagnetic resonance (EPR) spectroscopy as a function of the mixing ratio of polycation and polyanion. At low mixing ratios a superposition of two spectral components is found. The fast‐motion component observed arises from chain segments of the polyacid in excess, which form a stabilizing shell around the PEC particles. The other one is a slow‐motion component, which is caused by the interaction of charged chain segments of the polyacid with the oppositely charged segments of the polycation in the core. At high mixing ratios, the spectra are dominated by the slow‐motion component, because the polyacid is exclusively located in the core. The study has shown that the outer extrema separation of the slow‐motion component decreases with increasing mixing ratio, i.e., the rotational mobility of the polyacid segments in the core increases when the excess of the polycation becomes larger. An increasing number of extrinsic polycation sites within the core of the PECs which reduces the density of intrinsic binding sites are assumed to be the reason.

show abstract

Segmental Dynamics of Poly(acrylic acid) in Polyelectrolyte Complex Coacervates Studied by Spin-Label EPR Spectroscopy

Cited by 28 publications

References 20 publications

A Global Minimization Toolkit for Batch-Fitting and χ2 Cluster Analysis of CW-EPR Spectra

A Global Minimization Toolkit for Batch-Fitting and χ2 Cluster Analysis of CW-EPR Spectra

Effects of Non-Electrostatic Intermolecular Interactions on the Phase Behavior of pH-Sensitive Polyelectrolyte Complexes

Influence of the Mixing Ratio on the Dynamics of Polymer Segments in Polyelectrolyte Complexes

Contact Info

Product

Resources

About