POLY(DIMETHYLSILOXANE)/NYLON-6 BLOCK-COPOLYMERS - MOLECULAR MOBILITY AT THE INTERFACE

The molecular mobility at the interface of poly(dimethylsiloxane) [PDMS]/nylon-6 block copolymers was investigated using dynamic mechanical analysis (DMA) and solid-state deuterium NMR. Using DMA, T-g depression of the nylon matrix was observed with increasing PDMS content, and the mechanical loss peaks were broadened to lower temperature. When the room-temperature line spectra of solid-state deuterium NMR were compared for nylon-6 homopolymer and PDMS/nylon-6 diblock copolymer, a dear difference was observed; a peak associated with highly mobile nylon was observed in the block copolymer spectrum. This high mobility peak. was observed even at -50 degrees C. Using a selectively deuterated triblock copolymer, the origin of this peak mas shown to arise from a shell of softened nylon in the vicinity of PDMS domains. This softening effect was lost at -80 degrees C where PDMS domains can crystallize. This softened shell is not only from the compositionally mixed interfacial zone but also from a fraction of the pure nylon region surrounding the interfacial zone.