Determination of Microphase Structure and Scale of Mixing in Poly(ε-caprolactone) (PCL)/Poly(vinyl chloride) (PVC) Blend by High-Resolution Solid-State -NMR Spectroscopy with Magic Angle Spinning and Cross Polarization

Abstract

High-resolution solid-state, pulsed Fourier-transform (FT) 13C-nuclear magnetic resonance (NMR) spectroscopy with magic angle spinning (MAS) and cross polarization (CP) was applied to a mechanical blend of poly-c-caprolactone (PCL) and poly(viny1 chloride) (PVC) with 50/50 weight ratio (% ) whose composition results in very complex morphology and phase structure in the solid state. Proton spin-lattice relaxation times, TI ('H) and Tip( 'H) , were used as a probe to determine the microphase structure, the degree of homogeneity in terms of the domain size, and the state of mixing of the blend. In particular, T1,('H ) was shown to be able to distinguish the separated domains at a level of a few nanometers; the scale of mixing was evaluated from the approximation based on spin-diffusion phenomenon to be - 4.7 nm below which two polymers were partially mixed and above which they were homogeneously mixed. Treatment of the Tip( 'H) data with two exponential decay functions resulted in a resolution of individual TI@'H( ) into rigid and mobile components, from which more detailed information on the phase structure and state of mixing were obtained