Swelling behaviour of PNIPAM-polyisoprene core-shell microgels at surface

• Published in: Colloid and polymer science Vol. 289; no. 5-6; pp. 603 - 612
• Main Authors: Horecha, Marta, Senkovskyy, Volodymyr, Schneider, Konrad, Kiriy, Anton, Stamm, Manfred
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01-04-2011; Springer Nature B.V
• Subjects: Arrays; Atomic force microscopy; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Complex Fluids and Microfluidics; Contact angle; Drying; Food Science; Isoprene; Microgels; Nanotechnology and Microengineering; Original Contribution; Physical Chemistry; Polymer Sciences; Shells; Soft and Granular Matter; Swelling; PNIPAM; Microgel; Switching effect; Core-shell particles; Responsive surface
• ISSN: 0303-402X; 1435-1536
• DOI: 10.1007/s00396-010-2312-9

Poly(
N
-isopropylacrylamide) (PNIPAM)-based microgels covered with hydrophobic but water-permeable shell were used for modification of a hydrophilic substrate with the aim to provide a ‘contraphilic’ wetting behaviour, namely, to make the surface more hydrophobic in water environment (polar medium) than in dry state in air (non-polar medium). Bottom-up approach has been applied for a stepwise preparation of a structured two-component surface.
Loosely packed
microgels self-organised into quasiperiodic arrays were chemically grafted to the hydrophilic, functionalised substrate. Afterwards, a surface-initiated polymerisation of isoprene was performed selectively from microgels making them hydrophobic. The surface was found to be water-sensitive, as observed by in situ AFM measurements. The surface fraction of the hydrophobic component increased from 13% in the dry state up to 25% in water due to swelling of the microgels. However, small contraphilic effect was recorded by water contact angle measurements because of a moderate lateral swelling of the core-shell microgels and due to a fast swelling of the microgels already upon the measurements.