Solubilisation and Release of Organic Compounds of Different Polarity by Interpolyelectrolyte Complexes Based on Block Copolymer Micelles

• Applicant: Professor Dr. Michael Gradzielski
• Subject Area: Preparatory and Physical Chemistry of Polymers
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 402765656

• Final Report Year: 2024

Final Report Abstract

The aim of this project was the development of well-defined interpolyelectrolyt complex (IPEC) micelles, which contain classical hydrophobic domains, but also very polar IPEC domains. This then allows to have two regions of very different polarity within one colloidal aggregate. This is be interesting as such aggregates should be very flexible with respect to their solubilisation properties. Such micellar aggregates were realised by two approaches. In the first one we produced copolymer micelles with a hydrophobic core and a polyelectrolyte shell, which became complexed with an oppositely charged polyelectrolyte, thereby forming an IPEC layer around the hydrophobic core. In the second approach we employed hydrophobically modified polyelectrolytes for the IPEC formation. The alkyl chains of this modification then form hydrophobic domains of micellar nature within the IPECs. For this purpose, we synthesised different required copolymers, i.e., block copolymers, hydrophobically modified polyelectrolytes as well as combinations thereof. In this work, length of the blocks, type of hydrophobic modification and its extent were varied over a large range. These copolymer polyelectrolytes were then employed in IPEC formation and these IPECs became comprehensively characterised by means of light and neutron scattering. Here we observed a very systematic dependence of the formation of hydrophobic domain on the length and the type of alkyl chain of the hydrophobic modification. Only if the alkyl chain was long enough, well-defined compact hydrophobic domains were formed. For shorter alkyl chains much more open aggregates structures were observed that became substantially compacted upon complexation with oppositely charged polyelectrolyte. In summary, one can control the aggregation behaviour over a larger range via the architecture of the constituting polyelectrolytes. The solubilisation properties of these IPECs were studied for a range of active agents of largely varying polarity. Here we observed that the solubilisation capacity of the IPECs for unpolar solubilisates depends mainly on type and extent of the hydrophobic modification, whereas one observes a substantial synergism for polar solubilisates, which then leads to an increase of the solubilisation capacity by a factor up to 100. Apparently, the concept of offering hydrophobic and IPEC domains within one aggregate can be very attractive for applications from the field of selective solubilisation and generally offers the option to control and enhance the solubilisation properties.

Publications

• Investigating the Structure of Ionically Assembled Complexes of Polyelectrolytes with Oppositely Charged Polyelectrolytes or Surfactants by Means of Small-Angle Neutron Scattering (SANS) Seminar Maier-Leibniz-Zentrum (MLZ), Garching
  M. Gradzielski, O. Kuzminskaya, M. Simon, Ö. Azeri, A. Feoktystov, R. Dalgliesh & I. Hoffmann
  
• An Investigation of Amphiphilic Polyacrylate Containing Block Copolymers. Polydays 2019: Polymer Science and Engineering in View of Digitalization, 11-13.09.2019, Berlin
  Ö. Azeri, D. Schönfeld, U. Keiderling & M. Gradzielski
  
• Influence of alcohol cosurfactants on structure and properties of SDS/ p DADMAC PESCs. 15th European Detergency Conference EDC, 23.10.2019, Berlin
  O. Kuzminskaya , I. Hoffmann, D. Clemens & M. Gradzielski
  
• Syntheses and Characterization of Hydrophobically Modified Polyacrylate Containing Block Copolymers. 49. Hauptversammlung der Kolloid- Gesellschaft, 23.-25.09.2019, Stuttgart
  Ö. Azeri, D. Schönfeld, A. F. Hörmann, L. Noirez & M. Gradzielski
  
• Synthesis and aggregation behavior of hydrophobically modified polyacrylates as polymeric amphiphiles - Variation of alkyl chain length. CESIO 3.-5.06.2019, München
  S. Riemer, Ö. Azeri, O. Kuzminskaya & M. Gradzielski
  
• Influence of long- and mid-chain alcohol cosurfactants on structure and properties of SDS/pDADMAC PESCs. 16th Zsigmondy Colloquium, 9.-11.03.2020, Düsseldorf
  O. Kuzminskaya, I. Hoffmann, D. Clemens, R. Dalgliesh & M. Gradzielski
  
• Structural control in micelles of alkyl acrylate-acrylate copolymers via alkyl chain length and block length. Colloid and Polymer Science, 298(7), 829-840.
  Azeri, Özge; Schönfeld, Dennis; Noirez, Laurence & Gradzielski, Michael
  
• Structural investigation of micelles of alkyl acrylate-acrylate copolymers and their Interpolyelectrolyte Complexes (IPECs). European Colloid and Interface Society (ECIS), 5.-10.09.2021 Athen, Griechenland
  Ö. Azeri, D. Schönfeld, B. Dai, L. Noirez, U. Keiderling & M. Gradzielski
  
• Viscosity of polyelectrolyte surfactant complexes (PESCs) – the importance of the choice of the polyelectrolyte. 15th European Detergency Conference EDC (virtual), 13.10.2021, Berlin
  O. Kuzminskaya, I. Hoffmann, D. Clemens & M. Gradzielski
  
• Viscosity of Polyelectrolyte Surfactant Complexes—The Importance of the Choice of the Polyelectrolyte Seen for the Case of PDADMAC Versus JR 400. Macromolecules, 54(10), 4615-4625.
  Kuzminskaya, Olga; Hoffmann, Ingo; Clemens, Daniel & Gradzielski, Michael
  
• Polyelectrolyte–Surfactant Complexes As a Formulation Tool for Drug Delivery. Langmuir, 38(44), 13330-13343.
  Gradzielski, Michael
  
• Solubilisation of drug molecules in IPEC based on PDADMAC and amphiphilic polyanions. 51. Hauptversammlung der Kolloid-Gesellschaft, 28-30.09.2022, Berlin
  O. Kuzminskaya, S. Riemer, C. Küppers, L. Almásy & M. Gradzielski
  
• Structure and Phase Behavior of Interpolyelectrolyte Complexes of PDADMAC and Hydrophobically Modified PAA (HM‐PAA). Macromolecular Chemistry and Physics, 224(1).
  Kuzminskaya, Olga; Riemer, Sven; Dalgliesh, Robert; Almásy, László; Hoffmann, Ingo & Gradzielski, Michael
  
• A Comparison of Interpolyelectrolyte Complexes (IPECs) Made from Anionic Block Copolymer Micelles and PDADMAC or q-Chitosan as Polycation. Polymers, 15(9), 2204.
  Azeri, Özge; Schönfeld, Dennis; Dai, Bin; Keiderling, Uwe; Noirez, Laurence & Gradzielski, Michael
  
• A Comparison of Interpolyelectrolyte-Complexes Made from Anionic-Block-Copolymer Micelles and PDADMAC or q-Chitosan as Polycation. 19th European Detergency Conference EDC, 25.10.2023, Berlin
  Ö. Azeri, D. Schönfeld, B. Dai, U. Keiderling, L. Noirez & M. Gradzielski
  
• Polymer–surfactant interaction for controlling the rheological properties of aqueous surfactant solutions. Current Opinion in Colloid & Interface Science, 63, 101662.
  Gradzielski, Michael