A DSC and XPS characterization of core–shell morphology of block copolymer nanoparticles

• Published in: Colloid and polymer science Vol. 298; no. 8; pp. 1095 - 1105
• Main Authors: Tkachenko, Vitalii, Josien, Ludovic, Schrodj, Gautier, Hajjar-Garreau, Samar, Urbaniak, Sébastien, Poly, Julien, Chemtob, Abraham
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-08-2020; Springer Nature B.V; Springer Verlag
• Subjects: Block copolymers; Characterization and Evaluation of Materials; Chemical Sciences; Chemistry; Chemistry and Materials Science; Complex Fluids and Microfluidics; Diameters; Food Science; Glass transition; Hydroxyethyl acrylate; Imaging techniques; Latex; Morphology; Nanoparticles; Nanotechnology and Microengineering; Original Contribution; Particulate composites; Phase separation; Photoelectrons; Physical Chemistry; Polymer Sciences; Polymers; Polystyrene resins; Self-assembly; Soft and Granular Matter; X ray photoelectron spectroscopy; Copolymers; Self-assembly; Modulated differential scanning calorimetry; Particle morphology; Structured latex; Dispersions; X-ray photoelectron spectroscopy
• ISSN: 0303-402X; 1435-1536
• DOI: 10.1007/s00396-020-04676-7

Self-assembly of amphiphilic block copolymer chains is known to produce core–shell nanoparticles, but imaging techniques have generally failed to provide clear evidence about the multiphase structure. We report herein the advantages and limitations of modulated temperature differential scanning calorimetry (MDSC) and X-ray photoelectron spectroscopy (XPS) for the morphology study of spherical poly(hydroxyethyl acrylate)-
b
-polystyrene diblock copolymer nanoparticles with an intensity-average diameter of 40 nm. Using lyophilized particles, MDSC is more informative than XPS since it allows the three morphological features of composite latex particles to be distinguished: polystyrene core, poly(hydroxyethyl acrylate) shell, and interface. In MDSC, phase separation is evidenced by two distinct increments of heat capacity (Δ
C
p
) in the glass transition regions of the two blocks. By measuring Δ
C
p
values, an interface weight fraction of 70% is measured that gradually decreases to 50% with annealing time (150 °C, 2 h), indicating a higher extent of phase separation.