Open AccessSelf-Assembly of Soluplus in Aqueous Solutions: Characterization and Prospectives on Perfume Encapsulation
Author(s) -
Constantina Sofroniou,
Piero Baglioni,
Marianna Mamusa,
Claudio Resta,
James Doutch,
Johan Smets,
Piero Baglioni
Publication year - 2022
Publication title -
acs applied materials and interfaces
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.535
H-Index - 228
eISSN - 1944-8252
pISSN - 1944-8244
DOI - 10.1021/acsami.2c01087
Subject(s) - materials science , polymer , chemical engineering , differential scanning calorimetry , micelle , small angle neutron scattering , aqueous solution , neutron scattering , organic chemistry , chemistry , scattering , physics , engineering , optics , composite material , thermodynamics
Soluplus is an amphiphilic graft copolymer intensively studied as a micellar solubilizer for drugs. An extensive characterization of the nanostructure of its colloidal aggregates is still lacking. Here, we provide insights into the polymer's self-assembly in water, and we assess its use as an encapsulating agent for fragrances. The self-assembly properties of Soluplus aqueous solutions were studied over a wide concentration range (1-70% w/w) by means of small-angle neutron scattering (SANS), differential scanning calorimetry, NMR, and rheometry. SANS analyses revealed the presence of polymeric micelles with a fuzzy surface interacting via a 2-Yukawa potential, up to 15% w/w polymer. Increasing the polymer concentration up to 55% w/w led to tightly packed micelles described according to the Teubner-Strey model. The ability of Soluplus to encapsulate seven perfume molecules, 2-phenyl ethanol, l-carvone, linalool, florhydral, β-citronellol, α-pinene, and R -limonene, was then examined. We showed that the fragrance's octanol/water partition coefficient (log K ow ), widely used to characterize the solubilization capacity, is not sufficient to characterize such systems and the presence of specific functional groups or molecular conformation needs to be considered. In fact, the combination of SANS, NMR, confocal laser scanning microscopy, and confocal Raman microscopy showed that the perfumes, interacting with different regions of the polymer aggregates, are able to tune the systems' structures resulting in micelles, matrix-type capsules, core-shell capsules, or oil-in-water emulsions.