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Novel Amphiphilic Styrene‐Based Block Copolymers for Induced Surface Reconstruction
Author(s) -
Funk Lutz,
Brehmer Martin,
Zentel Rudolf,
Kang Huiman,
Char Kookheon
Publication year - 2008
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.200700312
Subject(s) - copolymer , polymer chemistry , amphiphile , polymer , monomer , materials science , contact angle , ethylene oxide , dispersity , polymerization , styrene , lamella (surface anatomy) , side chain , chemical engineering , molar mass , chemistry , composite material , engineering
This paper describes the synthesis of amphiphilic block copolymers by living radical polymerization (NMP) of new styrene‐like monomers. The polar monomers (ethylene oxide side chains and free hydroxyl‐ or amino‐groups after deprotection) were polymerized in a “protected form” to adjust the solubility of the monomers. In this way high molar mass polymers with a narrow polydispersity (around or below 1.2) were accessible. In the bulk state hydrophobic and hydrophilic domains demix. By exposing thin films of these polymers to vacuum (air) or alternatively to water or a hydrophilic surface it becomes possible to switch the surface polarity reversibly between contact angles of about 105° and 83° as a result of surface reconstruction. Through side chains of different length and with different functionalities, it was possible to adjust the glass transition temperatures to values between −2 °C to 140 °C for the hydrophilic blocks and −30 °C to 100 °C for the hydrophobic block. The wide range of the glass temperatures allowed it to find a block copolymer system with a slow kinetic concerning the surface reconstruction process, so that a mechanistic examination of the process by AFM was possible. It got, thereby, possible to detect the break‐up of the hydrophobic surface lamella and the upfold of the hydrophilic lamella in contact with water.