Reference : Stereocomplexation of sPMMA-PBD-sPMMA triblock copolymers with isotactic PMMA. II: Ef...
Scientific journals : Article
Engineering, computing & technology : Materials science & engineering
Physical, chemical, mathematical & earth Sciences : Chemistry
http://hdl.handle.net/2268/15056
Stereocomplexation of sPMMA-PBD-sPMMA triblock copolymers with isotactic PMMA. II: Effect of molecular weight
English
Yu, Jian Ming [University of Liège (ULg) > Department of Chemistry > Center for Education and Research on Macromolecules (CERM) > >]
Jérôme, Robert mailto [University of Liège (ULg) > Department of Chemistry > Center for Education and Research on Macromolecules (CERM) > >]
Dec-1998
Polymer
Elsevier Sci Ltd
39
25
6567-6575
Yes (verified by ORBi)
International
0032-3861
Oxford
[en] thermoplastic elastomer ; block copolymer
[en] Thermoplastic elastomers consisting of triblock copolymers (MBM) with outer syndiotactic poly(methyl methacrylate) (sPMMA) blocks associated to an inner polybutadiene (PBD) block have been modified by stereocomplexation with isotactic PMMA (iPMMA) at a constant 2/1 sPMMA/iPMMA (or s/i) mixing ratio. Toluene cast films of these stereocomplexes have been studied by thermal analysis as a function of molecular weight of the sPMMA blocks and the iPMMA homopolymer. Although the melting temperature of the stereocomplex (Tm) is independent of molecular weight of the sPMMA blocks ( sPMMA) in the studied range from 7000 to 46 000, the melting enthalpy increases with increasing sPMMA. This effect is, however, erased by the sample annealing at 140°C for 15 h, and a melting enthalpy of cα. 33 J/g total PMMA is then observed whatever the copolymer composition. One melting endotherm is observed in case of low sPMMA. although two melting endotherms are reported for higher sPMMA depending, however, on the heating rate. Two endotherms are indeed observed at small sPMMA as the heating rate is low. Molecular weight of iPMMA has no significant effect on either the melting temperature or the melting enthalpy of the stereocomplexes. Dynamic mechanical analysis has confirmed the phase separation of the complexed triblock copolymers. At constant molecular weight of PBD and iPMMA, stereocomplexation increases the tensile strength of MBM copolymers containing small sPMMA blocks, whereas the opposite effect is observed for longer sPMMA blocks. When the same MBM copolymer is complexed by iPMMA, the tensile properties are independent of the molecular weight of iPMMA at least in the range from 5000 to 74 000.
Center for Education and Research on Macromolecules (CERM)
The "IWT" (Flemish Insititute for Science-Technological Research in industry) ; Raychem N. V. ; Politique Scientifique Fédérale (Belgique) = Belgian Federal Science Policy
Researchers
http://hdl.handle.net/2268/15056
10.1016/S0032-3861(97)10250-6
http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6TXW-3V3YXJ2-1P-4&_cdi=5601&_user=532038&_orig=browse&_coverDate=12%2F31%2F1998&_sk=999609974&view=c&wchp=dGLbVlb-zSkWb&md5=e45748e03e159bca71f4af73b312185b&ie=/sdarticle.pdf
http://www.elsevier.com/wps/find/journaldescription.cws_home/30466/description#description
The authors acknowledge Polymer (Elsevier) for allowing them to archive this paper.

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