科研之友
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摘要
There is the need for novel polyelectrolytes with enhanced thermal and mechanical properties. In this report, we have reinforced a polyelectrolyte based on poly(dimethylaminoethylmethacrylate) (PDMAEM) using nanoclay montmorillonite (MMT), and have studied the thermal and viscoelastic properties. The protonated polymer (PDMAEMH) was solution mixed with functionalized MMT. Recognizing that the sort of surfactant may have a profound influence on the physical properties of the polymer matrix, neat MMT, and MMT treated with different surfactants (sulfobetaine and ammonia) were used, and the concentration of the nanofiller was varied from 1 to 5% w/w. Strikingly, while PDMAEM exhibited a glass transition temperature T(g) of 32 degrees C, the protonated PDMAEMH showed T(g) = 155 degrees C. Master curves obtained by applying the time-temperature superposition principle showed that PDMAEM behaved predominantly elastic (G %26apos;%26apos; %26lt; G%26apos;) suggesting an entangled polymer melt. However, PDMAEMH exhibited much longer relaxation times, a shift of ca. seven decades in frequency, suggesting that ionic interactions significantly hampered the molecular dynamics. X-ray scattering demonstrated that lower concentration and sulfobetaine surfactant favored exfoliation whereas ammonia and untreated MMT favored intercalation of the nanoplates. Furthermore, an enhancement in dynamic storage shear modulus was observed for the nanocomposites exhibiting intercalated morphologies relative to those displaying an exfoliated morphology. It is then suggested that the molecular dynamics is further slowed down due to confinement of the macromolecules between the nanoplates.
- 出版日期2012-1-15
