Premium
Correlation between Molecular Architecture, Morphology, and Deformation Behaviour of Styrene/Butadiene Block Copolymers
Author(s) -
Adhikari Rameshwar,
Michler Goerg H.,
Huy Trinh An,
Ivan'kova Elena,
Godehardt Reinhold,
Lebek Werner,
Knoll Konrad
Publication year - 2003
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.200390022
Subject(s) - copolymer , materials science , lamellar structure , morphology (biology) , phase (matter) , thermoplastic elastomer , composite material , deformation (meteorology) , polystyrene , polymer chemistry , polymer , chemistry , genetics , organic chemistry , biology
The correlation between the molecular architecture, morphology, and micromechanical deformation behaviour of styrene/butadiene (SB) block copolymers with different architectures (linear and star block copolymers, total styrene content, Φ ST = 0.74) was studied using dynamic mechanical analysis (DMA), uniaxial tensile testing, scanning force microscopy (SFM), and high voltage electron microscopy (HVEM). Deformation of the individual phases under uniaxial strain at the molecular level was monitored by Fourier transform infrared (FT‐IR) spectroscopy. It was demonstrated that the morphology and deformation behaviour of these block copolymers are strongly influenced by their molecular topology, block symmetry, and the nature of the interface between the component blocks. While the cylindrical morphology (hexagonal polybutadiene (PB) cylinders in polystyrene (PS) matrix) was observed in a symmetric SBS triblock copolymer with Φ ST = 0.74, a “two‐component three‐phase” morphology was found in an asymmetric star block copolymer having an equivalent chemical composition and an SBS arm structure. Likewise, an SBS triblock copolymer with a composition identical to the former ones but with highly asymmetric PS end blocks revealed a lamellar morphology. While no locally confined deformation zones were observed in the lamellar block copolymers, the cylindrical block copolymer was found to deform through the formation of highly localised craze‐like deformation zones.SFM phase images showing lamellae‐like morphology of the star block copolymer ST2, phase difference 25 degrees.