Lamellar block copolymers as viewed by deuterium NMR spectroscopy Srećko Valić 1,2, Božica Šorgić 1, Bertrand Deloche 3, Yves Gallot 4 1 Ruđer Bošković Institute POB 180, HR Zagreb, Croatia 2 Faculty of Medicine Braće Branchetta 20, HR Rijeka, Croatia 3 Laboratoire de Physique des Solides Bât. 510, F Orsay, France 4 Institut Charles Sadron 6 rue Boussingault, F Strasbourg, France

Block copolymers Strong segregation limit (SSL): N  >> 10 N – degree of polymerization  – Flory-Huggins interaction parameter Microdomains: structure - chemical composition (A/B) size depends on N A diblock triblock A B A B How this organization of the molecules affects segmental dynamics?

Deuterium NMR spectroscopy I = 1 H = H Z + H Q H Q = 0H Q >0    Quadrupolar splitting q quadrupolar coupling constant  the angle between B and n  (t) the angle between n and C-D bond PARTICULAR CASE: UNIAXIAL MOLECULAR MOTIONS MAGIC ANGLE  = 54° 44' 8'' =0No doublet ! Direct mesure of the orientational order parameter S

Samples a) PS-PB M w =84000 (42000 per block) PBD free chains M w =4600 PSPB b) PS-PB-PS M w =80700 ( ) PBD free chains M w =4600 PSPB d) PS-PDMS M w =91000 (40000 for PS and for PDMS) PSPDMS C 8 D 18 b) PS-PBD Mw=84000 (42000 per block) PSPBD Perdeuterated PB block

Results a) PS-PB + PBD probe chains b) PS-PB-PS + PBD probe chains  = 0º  = 28 Hz  = 0º  = 32 Hz T=100º C S~10 -4 =CD- -CD 2 -

Motions of the PBD chains are uniaxial in direction n PB matrix chains are elongated in direction n PS diblock PS-PB triblock PS-PB-PS PS loop entangled loop bridge tail |P 2 (cos  )|  = 0°

PB rubber (M c = 40000) + PBD =1  >1  = 90°

c) PS-PBD T=160º C  °  = 28 Hz The same value  is measured for PBD probe chains in nondeuterated PS-PB matrix at 100 º C. Dynamics of deuterated matrix chains is slower than that of nondeuterated. Spectral wings: - a strong dynamic gradient along the PBD chains of the PS-PBD diblock =CD- -CD 2 -

PS-PDMS + C 8 D 18 PS PDMS C 8 D 18 T/K  = f(T) DSCT m = 237 K  = f(T)

T = 219 K The amorphous phase of the PDMS block is under a strong uniaxial constraint in the presence of crystalline phase.

n S > 0 S < 0

=1  >1 experimentcalculation