Tailored conditions for controlled and fast growth of surface-grafted PNIPAM brushes

Published Date
Polymer
5 August 2016, Vol.97:380–386, doi:10.1016/j.polymer.2016.05.048

• Author 

• A. Pomorska ¹
• K. Wolski ¹
• A. Puciul-Malinowska
• S. Zapotoczny ^,

• Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow, Poland

Received 29 March 2016. Revised 17 May 2016. Accepted 18 May 2016. Available online 19 May 2016. 

Highlights

• •
  PNIPAM brushes follow reversible “coil to globule” transition in water/methanol.
• •
  Globular conformation of the brushes is in wider range of water/methanol mixtures.
• •
  SI-ATRP of PNIPAM proceeds in a controlled way in solutions of 0.16 < x_methanol < 0.31.

Abstract

Surface-initiated Atom Transfer Radical Polymerization is an established technique for synthesis of polymer brushes via “grafting from” method. However, dynamic behavior of surface-tethered macromolecules during their growth requires more detailed studies to obtain uniform polymer brush films. It was addressed here by varying solvent composition in grafting of poly(N-isopropylacrylamide) brushes. Complementary in situ (quartz crystal microbalance) and ex situ (atomic force microscope, spectroscopic ellipsometry) techniques were employed to investigate the influence of methanol molar fraction (x_Me) in methanol/water polymerization mixture on the brush growth. Grazing-angle polarized FT-IR spectroscopy was used to monitor macromolecular arrangement in the brushes. While achieving controlled, uniform and relatively fast growth of macromolecules is challenging a compromise may be reached by tuning solvent composition. The most balanced conditions with this respect were found in a narrow solvent composition window at ca. x_Me ≈ 0.16 and below 0.31. The results may be applied for tailoring polymerization conditions of other polymer brush systems.

Graphical abstract

Keywords

• Polymer brushes
• Interfacial molecular arrangement
• In situ SI-ATRP
• Tailored conditions

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  Corresponding author.

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