resumo
We report on the segregation and microstructure of poly[9,9-bis(2-ethylhexyl)-fluorene] (PF2/6) blended in polyethylene (PE) aligned by tensile drawing at elevated temperature. X-ray diffraction and photoluminescence data indicate that when the PF2/6 fraction is high (7-15 wt %), PF2/6 assembles in uniaxially aligned crystallites (the coherence length similar to 32 nm) segregated within the PE matrix. The full-width-half-maximum of the PF2/6 crystallite orientation distribution about the stretching direction is <= 10 degrees. No significant macrophase separation is observed with A FM or optical and fluorescence microscopy. When the PF2/6 fraction is low (0.25 wt %), aligned PF2/6 forms a frozen-in nematic-like phase. The aligned polymers remain closely located bill their coherence length is significantly decreased (similar to 8 nm), which is attributed to the decreased crystallite size. This behavior differs from that of poly(phenylene-vinylene) type polymers and the difference is rationalized by compatibility and entanglement arguments.
palavras-chave
STRUCTURE-PROPERTY RELATIONSHIPS; HAIRY-ROD POLYFLUORENE; LIGHT-EMITTING-DIODES; CONJUGATED POLYMERS; PHOTOPHYSICAL PROPERTIES; ELECTROSPUN NANOFIBERS; OPTICAL-PROPERTIES; THIN-FILMS; MORPHOLOGY; ORIENTATION
categoria
Polymer Science
autores
Knaapila, M; Vaughan, HL; Hase, TPA; Evans, RC; Stepanyan, R; Torkkeli, M; Burrows, HD; Scherf, U; Monkman, AP
Grupos
agradecimentos
The XRD experiments Were Supported by the EC (RII3-CT-2004-506008 (IA-SFS)) and the XMaS project. R.C.E would like to thank FCT for a postdoctoral fellowship (SFRH/BPD/42450/2007). Thanks are moreover due to Wolfgang Caliebe of HASYLAB and Laurence Bouchenoire of the ESRF for assistance.