²H NMR spin relaxation study of the soft segment motion in alternating ethylene–propylene copolymers

Abstract

We synthesized three partially deuterated polymer samples, namely a poly(ethylene-alt-propylene) (EP) alternating copolymer, a poly(styrene-b-EP) diblock copolymer (SEP) and a poly(styrene-b-EP-b-styrene) triblock copolymer (SEPS). The 2 H spin-lattice relaxation time, T 1 , of EP soft segments above their glass transition temperature was measured by solid-state 2 H NMR spectroscopy. It was found that the block copolymers had a fast and a slow T 1 component whereas EP copolymer had only a fast component. The fast T 1 components for SEP and SEPS are similar to the T 1 value of EP above ca 20• C. The slow T 1 component for SEP and SEPS exhibited a minimum at 60• C and approached the value of the fast component near the T g of polystyrene. The motional behavior of the EP units for SEP is similar to that of SEPS over the entire range of temperature.

Motional Heterogeneity in Poly(ether-block-amide) Copolymers As Revealed by Solid-State NMR

“…Solid-state NMR spectroscopy is now recognized as one of the most powerful tools for structural and dynamic studies of polymeric materials. Several research groups used indeed solid-state NMR methods, based on proton spin-diffusion phenomena, to investigate the phase structure and to determine the rigid and mobile domain sizes on the nanometer length scale (typically between 2 and 30 nm) as well as the sizes of interphases (0.5−2.5 nm) in a number of block copolymers. − Some attention has been also paid to the investigation of molecular mobility of block copolymers by proton, deuterium, − and carbon-13 17,26-29 solid-state NMR techniques.…”