Abstract
The aim of this paper is the achievement of films characterized by axially oriented nanoporous-crystalline (NC) and co-crystalline (CC) phases of poly(2,6-dimethyl-1,4-phenylene)oxide (PPO). Axiall...
Highlights
Two commercially available polymers, i.e., syndiotactic polystyrene[1−3] and poly(2,6-dimethyl-1,4-phenylene)oxide (PPO),[4,5] are able to form co-crystalline (CC) phases with many low-molecular-mass guest molecules[6] as other commercial polymers such as poly(L-lactide),[7] or poly(vinylidene fluoride),[8] but are rather unique as for their ability to maintain crystalline cavities after guest removal, forming nanoporous crystalline (NC) phases
This paper describes a successful attempt to get axially oriented NC phases of PPO, which is based on a down-shift of the useful stretching temperature range, being obtained by using miscible blends of PPO with atactic polystyrene that exhibit strongly reduced Tg.[53−57,61]
It is assumed that the transition moment vector (TMV) associated with this vibrational mode is parallel to the chain axes (θ = 0°)
Summary
I.e., syndiotactic polystyrene (sPS)[1−3] and poly(2,6-dimethyl-1,4-phenylene)oxide (PPO),[4,5] are able to form co-crystalline (CC) phases with many low-molecular-mass guest molecules[6] as other commercial polymers such as poly(L-lactide),[7] or poly(vinylidene fluoride),[8] but are rather unique as for their ability to maintain crystalline cavities after guest removal, forming nanoporous crystalline (NC) phases. IR linear dichroism measurements on films with axial orientation[37−42] have been useful for the determination of host−guest relative orientations These studies, in agreement with the crystalline structures of some CC forms,[43−49] have established that planar molecules are generally oriented with the molecular plane roughly perpendicular and parallel to the polymer chain axes when they are guests of NC δ and ε forms, respectively. The present paper reports the first polarized IR spectra of a CC film of PPO and allows establishing that their benzene guest molecules are oriented with their molecular plane roughly parallel to the PPO chain axes This suggests the presence of empty channels, as well established for the NC orthorhombic ε form of sPS.[2,6]
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