Influence of intramolecular charge coupling on intermolecular interactions of polycarboxybetaines in aqueous solution and in polyelectrolyte multilayers

Abstract

The present paper deals with the correlation between intramolecular and intermolecular interactions of polycarboxybetaines. The degree of coupling between the opposite charges within the polycarboxybetaine molecules was varied by spacers of different length and by the substitution of additional alkyl chains at the quaternary nitrogen atom. In order to check intermolecular interactions between polycarboxybetaines, SANS measurements were carried out at aqueous polycarboxybetaines solutions. For getting information about the interaction with an oppositely charged polyelectrolyte, multilayers were formed by alternating adsorption of polystyrene sulfonate (PSS) and polycarboxybetaines from aqueous solutions. The occurrence of a structure peak in SANS spectra and the ability to form polyelectrolyte multilayers provide an indicator for the polyelectrolyte character of some of the studied polycarboxybetaines. Not only the charge but also the hydrophobicity of the polycarboxybetaines has a pronounced effect on the chain conformation and therefore on the thickness of the polyelectrolyte multilayers. The results show that small differences in molecular architecture lead to pronounced differences in intermolecular interactions.

GRAPHICAL ABSTRACT

Keywords:

• Polycarboxybetaines
• intermolecular interactions
• intramolecular interactions
• polyelectrolyte multilayer
• chain conformation

Acknowledgments

First of all we would like to thank Werner Jaeger who came up with the idea to study Polycarboxybetaines long time ago. He passed away in 2011. Julian Oberdisse, Thomas Schimmel and Regine von Klitzing acknowledge the French–German Network (supported by DFG, MPG, CEA and CNRS) and the LLB (CEA) for financing the SANS experiments at the LLB in Saclay. The two months stay of Dan F. Anghel in the group of Regine von Klitzing was financed by the SFB 448 – subproject B10 (DFG). Our special thanks go to Gerhard Findenegg who was spokeperson of the SFB 448 ‘Mesoscopically structured composite systems’ from 1998 to 2006 and PI of the before–mentioned French–German network, where Julian Oberdisse met him for the first time. In the early 2000s, he created the idea together with Keith Gubbins from North Carolina State University (NCSU) in Raleigh to establish an international graduate school between universities in North Carolina and universities and research institutes in the Berlin/Brandenburg area which finally led to the graduate school IRTG 1524 ‘Self-Assembled Soft Matter Nano-Structures at Interfaces’ financed by the DFG (2009–2017). Not only in these collaborative projects but also in daily lab-life, we could experience Gerhard Findenegg as an excellent and enthusiastic scientist.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by German Research Foundation [French-German Network,SFB 448, TP B10].