Dynamic study of polystyrene-block-poly(4-vinylpyridine) copolymer in bulk and confined in cylindrical nanopores

POLYMER

卷:55

Article

Maiz, Jon^1,2,3  Zhao, Wei²  Gu, Yu²  Lawrence, Jimmy²  Arbe, Arantxa³  Alegria, Angel^3,4  Emrick, Todd²  Colmenero, Juan^3,4,5  Russell, Thomas P.²  Mijangos, Carmen¹ 

[1] CSIC, Inst Ciencia & Tecnol Polimeros, E-28006 Madrid, Spain

[2] Univ Massachusetts, Dept Polymer Sci & Engn, Amherst, MA 01003 USA

[3] CSIC UPV EHU, Ctr Fis Mat, San Sebastian 20018, Spain

[4] Univ Basque Country, UPV EHU, Dept Fis Mat, San Sebastian 20080, Spain

[5] Donostia Int Phys Ctr, San Sebastian 20018, Spain

关键词: Dielectric spectroscopy broadband;    AAO templates;    PS-b-P4VP copolymers;   

DOI  :  10.1016/j.polymer.2014.05.042

来源: Elsevier

【 摘 要 】

AAO template is highly recommended to nanostructure polymers and to study polymer properties under confinement. The dynamic properties of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) under confinement using broadband dielectric spectroscopy are investigated in this work and the results compared to those of the bulk. Anodized aluminum oxide (AAO) membranes, having pore diameters from tens to hundreds of nanometers in size, were used to confine PS-b-P4VP. Moreover, the influence of gold nanoparticles (AuNPs) in the copolymer matrix was also studied. The morphology and structure of the bulk copolymer and the copolymer confined in the AAO templates were characterized by transmission electron microscopy, scanning electron microscopy and Small Angle X-Ray Scattering. For PS-b-P4VP in bulk, dielectric relaxation techniques allowed studying selectively the P4VP segmental dynamics within the diblock. At high temperature this copolymer presents a dominant peak (MWS relaxation), most likely originated by the relatively high conductivity combined with the presence of interfaces emerging in the nanostructured samples. Moreover, a pronounced beta-relaxation is observed for the copolymer compared with that of pure P4VP. This is likely due to a non-negligible contribution from the alpha-relaxation of the PS component. The gamma-relaxation is markedly different in the copolymer, which is evidenced by a distinct temperature dependence of the resulting relaxation times. When the copolymer is embedded in alumina nanopores with small pore diameters (25 and 35 nm) there are significant changes, where the tendency is going to a faster dynamics when the pore diameter decreases more likely related to the relevance of surface effects. The presence of the AuNPs in the system enhances this effect. These results are in agreement with segregated structures found in the block copolymer by TEM and SAXS. (C) 2014 Elsevier Ltd. All rights reserved.

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