The miscibility, crystallization, vitrification, and melting behavior of multiblock copolymers consisting of alternating components of oligo[imino(1-oxododecamethylene)] and oligo(oxytetramethylene) were investigated in their dependence of composition and molecular mass of the blocks. In all compositions studied, the copolymers present two separate glass transitions at temperatures not far from those of the corresponding homopolymers. The immiscible components are linked by chemical bonds to nanophase-separated layers. In such a situation, the structure and mobility of each phase affect the other, causing small shifts of the glass-transition temperatures. The enthalpy-based crystallinity was calculated separately for each component, using the known information on heat capacities and latent heats. The crystallinity is influenced by the block lengths. The oligoamide segments crystallize from an isotropic melt with a relatively high crystallinity, whereas the oligoether blocks solidify in the presence of cr ystals and glass of the second component in the adjacent solid nanophases, which greatly reduces their overall long-range chain mobility, and as a consequence, their crystallinity is rather small.
Calorimetry of nanophase-separated poly(oligoamide-altoligoether)s
Di Lorenzo ML;
2001
Abstract
The miscibility, crystallization, vitrification, and melting behavior of multiblock copolymers consisting of alternating components of oligo[imino(1-oxododecamethylene)] and oligo(oxytetramethylene) were investigated in their dependence of composition and molecular mass of the blocks. In all compositions studied, the copolymers present two separate glass transitions at temperatures not far from those of the corresponding homopolymers. The immiscible components are linked by chemical bonds to nanophase-separated layers. In such a situation, the structure and mobility of each phase affect the other, causing small shifts of the glass-transition temperatures. The enthalpy-based crystallinity was calculated separately for each component, using the known information on heat capacities and latent heats. The crystallinity is influenced by the block lengths. The oligoamide segments crystallize from an isotropic melt with a relatively high crystallinity, whereas the oligoether blocks solidify in the presence of cr ystals and glass of the second component in the adjacent solid nanophases, which greatly reduces their overall long-range chain mobility, and as a consequence, their crystallinity is rather small.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
