Molecular Mobility in Oriented and Unoriented Membranes Based on Poly[2-(Aziridin-1-yl)ethanol

Roberto Teruel-Juanes,Jose A Reina,Krzysztof Artur Bogdanowicz,Victor Sáenz De Sáenz De Juano-Arbona,Marta Giamberini,Jose D Badia,Amparo Ribes-Greus,Robert Graf

doi:10.3390/polym13071060

Abstract

Unoriented and oriented membranes based on dendronized polymers and copolymers obtained by chemical modification of poly[2-(aziridin-1-yl) ethanol] (PAZE) with the dendron 3,4,5-tris[4-(n-dodecan-1-yloxy)benzyloxy]benzoate were considered. DSC, XRD, CP-MAS NMR and DETA, contribute to characterize the tendency to crystallize, the molecular mobility of the benzyloxy substituent, the dendritic liquid crystalline group and the clearing transition. The orientation of the mesogenic chain somewhat hindered this molecular motion, especially in the full substituted PAZE. The fragility, free volume and thermal expansion coefficients of these membranes near the glass transition are related to the orientation and the addition of the dendritic groups. PAZE-based membranes combine both order and mobility on a supramolecular and macroscopic level, controlled by the dendritic group and the thermal orientation, and open the possibility of preparing membranes with proper channel mobility that promotes selective ionic transport.

Highlights

Liquid crystals (LCs) can be considered as prototypical self-organizing molecular materials because their structural organization stands between the isotropic liquid and the strongly organized crystalline state
May be related to the melting of a small crystalline portion, while the latter relates to5 of the clearing transition, both associated to the lateral mesogenic chains
Differential Scanning Calorimetry (DSC), X-ray diffraction (XRD) and NMR studies show that all the studied native unoriented membranes based on dendronized polymers and copolymers obtained by chemical modification of poly[2-(aziridin-1-yl) ethanol] (PAZE) with the dendron 3,4,5-tris[4-(n-dodecan1-yloxy)benzyloxy]benzoate show a liquid crystal mesophase

Summary

Introduction

Liquid crystals (LCs) can be considered as prototypical self-organizing molecular materials because their structural organization stands between the isotropic liquid and the strongly organized crystalline state. With the dendron 3,4,5-tris[4-(n-dodecan-1-yloxy)benzyloxy] benzoate exhibit a liquid crystalline columnar structure [6,7,8,9,10,11,12,13], due to a self-assembly process driven by the exorecognition of the dendritic moieties [14]. As a result, their main chains form an arrangement of columnar channels and the presence of the basic nitrogen in the inner part facilitates the interaction with protons and other cations. It might be desirable to get further insight into the dynamics of large supramolecular building blocks of these materials, in order to improve their self-assembly and optimize their performances [14,15,16]

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Conclusion