Thermoreversible Cis<i>−</i>Cisoidal to Cis<i>−</i>Transoidal Isomerization of Helical Dendronized Polyphenylacetylenes
作者:Virgil Percec、Jonathan G. Rudick、Mihai Peterca、Martin Wagner、Makoto Obata、Catherine M. Mitchell、Wook-Dong Cho、Venkatachalapathy S. K. Balagurusamy、Paul A. Heiney
DOI:10.1021/ja055406w
日期:2005.11.1
Phi(h,k)-to-Phi(h)(io)-to- Phi(h) phase transition in these dendronized PPAs was analyzed by a combination of differential scanning calorimetry and small and wide-angle X-ray diffraction experiments performed on powder and oriented fibers. In the Phi(h,k) and Phi(h)(io) phases, the dendronized PPAs form helical porous columns. The helical pore disappears in the Phi(h) phase. This change is accompanied
高顺式含量 (81-99%) 顺式-反式聚苯乙炔 (PPA),夹有两亲性自组装树突,聚 [(3,4-3,5)mG2-4EBn],m = 8, 10, 12, 14, 16 和 (S)-3,7-二甲基辛基由 Rh(C 三键 CPh)(nbd)(PPh(3))(2) (nbd = 2,5-降冰片二烯)/N,N-(二甲氨基)吡啶(DMAP)催化大分子单体聚合。由此产生的圆柱形 PPA 自组织成具有柱内顺序 (Phi(h)(io)) 和无 (Phi(h)) 的六边形柱状晶格。m = 12、14 和 16 的聚合物也表现出六方柱状晶相 (Phi(h,k))。通过差示扫描量热法和小广角 X 射线衍射的组合分析了这些树枝状 PPA 中的可逆 Phi(h,k) 到 Phi(h)(io) 到 Phi(h) 相变对粉末和定向纤维进行的实验。在 Phi(h,k) 和 Phi(h)(io) 相中,树枝状 PPA 形成螺旋多孔柱。螺旋孔在