Surface Grafted Chitosan Gels: Part I. Molecular Insight into the Formation of Chitosan and Poly(acrylic acid) Multi layers
2014 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 30, no 29, 8866-8877 p.Article in journal (Refereed) Published
Composite polyelectrolyte multilayers of chitosan and low molecular weight poly(acrylic acid) (PAA) have been assembled by sequential adsorption as a first step toward building a surface anchored chitosan gel. Si lane chemistry was used to graft the first chitosan layer to prevent film detachment and decomposition. The assembly process is characterized by nonlinear growth behavior, with different adsorption kinetics for chitosan and PAP.. In situ analysis of the multilayer by means of surface sensitive total internal reflection Raman (TIRR) spectroscopy, combined with target factor analysis of the spectra, provided information regarding composition, including water content, and ionization state of weak acidic and basic groups present in the thin composite film. Low molecular weight PAA, mainly in its protonated form, diffuses into and out of the composite film during adsorption and rinsing steps. The higher molecular weight chitosan shows a similar behavior, although to a much lower extent. Our data demonstrate that the charged monomeric units of chitosan are mainly compensated by carboxylate ions from PAP.. Furthermore, the morphology and mechanical properties of the multilayers were investigated in situ using atomic force microscopy operating in PeakForce tapping mode. The multilayer consists of islands that grow in lateral dimension and height during the build-up process, leading to close to exponentially increasing roughness with deposition number. Both diffusion in and out of at least one of the two components (PAA) and the island-like morphology contribute to the nonlinear growth of chitosan/PAA multilayers.
Place, publisher, year, edition, pages
2014. Vol. 30, no 29, 8866-8877 p.
Adsorption, Atomic force microscopy, Carboxylation, Carboxylic acids, Chitosan, Composite films, Grafting (chemical), Mechanical properties, Molecular weight, Morphology, Polyelectrolytes, Refractive index, Low molecular weight, Morphology and mechanical properties, Peak-force tappings, Polyelectrolyte multilayer, Sequential adsorption, Target factor analysis, Thin composite films, Total internal reflections
IdentifiersURN: urn:nbn:se:kth:diva-149982DOI: 10.1021/la5013186ISI: 000339686700028ScopusID: 2-s2.0-84905055244OAI: oai:DiVA.org:kth-149982DiVA: diva2:742311
FunderSwedish Research CouncilSwedish Foundation for Strategic Research
QC 201409012014-09-012014-08-292014-09-01Bibliographically approved