Toward Strong Thermoplastic Elastomers with Asymmetric Miktoarm Block Copolymer Architectures
Abstract
Thermoplastic elastomers (TPEs) are designed by embedding discrete glassy or semicrystalline domains in an elastomeric matrix. Typical styrenic-based amorphous TPEs are made of linear ABA-type triblock copolymers, where the volume fraction f of the glassy domains A is typically less than 0.3. This limitation ultimately restricts the range of mechanical strength attainable with these materials. We had previously predicted using self-consistent field theory (SCFT) that A(BA )n miktoarm block copolymers with an approximately 8:1 ratio of the A to A block molecular weights and n 3 should exhibit discrete A domains at considerably larger f and offer potential for the combination of high modulus, high recoverable elasticity, and high strength and toughness. Using transmission electron microscopy and small-angle X-ray scattering on model polystyrene-b-polyisoprene (PS-PI) miktoarm copolymers, we show that such polymers indeed possess discrete PS domains for f values considerably higher than 0.3. The hexagonal morphology with PS cylinders was achieved for f = 0.5 and n = 3. Mechanical testing indicates that these miktoarm materials are strong, tough, and elastic and thus may be potential candidates for a new generation of thermoplastic elastomers.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 05, 2014
- Accession Number
- ADA616077
Entities
People
- Alexander Hexemer
- Apostolos Avgeropoulos
- Christos Ntaras
- Damien Montarnal
- Edward J. Kramer
- Glenn H. Fredrickson
- Nathaniel A. Lynd
- Weichao Shi
- Yingdong Luo
Organizations
- University of California, Santa Barbara