Salt- and pH-induced swelling of a poly(acrylic acid) brush via quartz crystal microbalance w/dissipation (QCM-D)

Nisha R. Hollingsworth , Sabina Wilkanowicz , Ronald G. Larson

Abstract

We infer the swelling/de-swelling behavior of weakly ionizable poly(acrylic acid) (PAA) brushes of 2–39 kDa molar mass in the presence of KCl concentrations from 0.1–1000 mM, pH = 3, 7, and 9, and grafting densities s = 0.12–2.15 chains per nm2 using a Quartz Crystal Microbalance with Dissipation (QCM-D), confirming and extending the work of Wu et al. to multiple chain lengths. At pH 7 and 9 (above the pKa B 5), the brush initially swells at low KCl ionic strength (o10 mM) in the ‘‘osmotic brush’’ regime, and de-swells at higher salt concentrations, in the ‘‘salted brush’’ regime, and is relatively unaffected at pH 3, below the pKa, as expected. At pH 7, at low and moderate grafting densities, our results in the high-salt ‘‘salted brush’’ +1/3 􏰀1/3 regime (Cs 4 10 mM salt) agree with the predicted scaling H B Ns Cs +1/3 low-salt ‘‘osmotic brush’’ regime (Cs o 10 mM salt), we find H B Ns Cs , whose dependence on Cs agrees with scaling theory for this regime, but the dependence on s strongly disagrees with it. The predicted linearity in the degree of polymerization N is confirmed. The new results partially confirm scaling theory and clarify where improved theories and additional data are needed.
Author Nisha R. Hollingsworth
Nisha R. Hollingsworth,,
-
, Sabina Wilkanowicz (FCEMP / IC)
Sabina Wilkanowicz,,
- The Institute of Chemistry
, Ronald G. Larson
Ronald G. Larson,,
-
Journal seriesSoft Matter, [SOFT MATTER], ISSN 1744-683X, e-ISSN 1744-6848, (N/A 100 pkt)
Issue year2019
Vol15
Pages7838-7851
Publication size in sheets0.65
Keywords in PolishQCM-D, kwas poliakrylowy, szczotka polimerowa
Keywords in EnglishQCM-D, poly(acrylic acid), polymeric brush
ASJC Classification1600 General Chemistry; 3104 Condensed Matter Physics
Abstract in PolishPrzedstawiono puchnięcie i zachowania odwrotne w słabo zjonizowanej szczotce polimerowej zbudowanej z kwasu poliakrylowego (PAA) o masie molowej 2-39 kDa obecności KCl o stężeniu 0,1-1000 mM, pH 3, 7 oraz 9 i gęstości przyczepienia 0,12-2,15 łańcuchów polimeru/nm2 z wykorzystaniem urządzenia QCM-D. W środowisku o pH powyżej pKa polimeru, szczotka wstępnie puchła w środowisku o niskim stężeniu KCl i wykazywała odwrotne zachowanie wraz ze wzrostem stężenia soli w środowisku. Zachowanie szczotki polimerowej w pH kwaśnym nie wpływało na zmianę napuchnięcia polimeru.
DOIDOI:10.1039/C9SM01289C
URL https://pubs.rsc.org/en/content/articlelanding/2019/sm/c9sm01289c#!divAbstract
Languageen angielski
Score (nominal)100
Score sourcejournalList
ScoreMinisterial score = 100.0, 01-01-2020, ArticleFromJournal
Publication indicators WoS Citations = 0; Scopus SNIP (Source Normalised Impact per Paper): 2017 = 1.227; WoS Impact Factor: 2018 = 3.399 (2) - 2018=3.632 (5)
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