Nanophase separation and hindered glass transition in side-chain polymers.
Nanophase separation on length scales of 1-5 nanometres has been reported previously for small-molecule liquids, metallic glasses and also for several semicrystalline, liquid-crystalline and amorphous polymers. Here we show that nanophase separation of incompatible main and side-chain parts is a general phenomenon in amorphous side-chain polymers with long alkyl groups. We conclude from X-ray scattering and relaxation spectroscopy data for higher poly(n-alkyl acrylates) (PnAA) and poly(n-alkyl methacrylates) (PnAMA) that alkyl groups of different monomeric units aggregate in the melt and form self-assembled alkyl nanodomains with a typical size of 0.5-2 nm. A comparison with data for other polymer series having alkyl groups reveals that important structural and dynamic aspects are main-chain independent. A polyethylene-like glass transition within the alkyl nanodomains is observed and discussed in the context of a hindered glass transition in self-assembled confinements. This is an interesting link between central questions in glass-transition research and structural aspects in nanophase-separated materials.
Beiner
Mario
M
Fachbereich Physik, Universität Halle, Hoher Weg 8, D-06099 Halle, Germany. beiner@physik.uni-halle.de
Huth
Heiko
H
D000179:Acrylates / Q000737:chemistry*; D000478:Alkylation; D003460:Crystallization / Q000379:methods*; D003461:Crystallography / Q000379:methods*; D018360:Crystallography, X-Ray; D008422:Materials Testing / Q000379:methods; D008689:Methacrylates / Q000737:chemistry*; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods*; D020959:Polyethylene / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D011109:Polymethacrylic Acids
D000179:Acrylates; D008689:Methacrylates; D011108:Polymers; D011109:Polymethacrylic Acids; D020959:Polyethylene