Nanoporous-crystalline films of PPO with parallel and perpendicular polymer chain orientations

Rizzo, Paola; Gallo, Chiara; Vitale, Vissia; Tarallo, Oreste; Guerra, Gaetano

doi:10.1016/j.polymer.2019.01.073

Cited by 36 publications

(89 citation statements)

References 83 publications

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“…These patterns show diffraction rings typical of the α form of PPO (at 2 θ CuKα ≈ 4.5°, 7.1°, 11.4°, 15.1°). These equatorial hk0 peaks are slightly polarized on the equator of the pattern, thus indicating the occurrence of a low degree of c // orientation, i.e., of an orientation of the chain axes of the crystalline phase being preferentially parallel to the film plane [ 52 ].…”

Section: Resultsmentioning

confidence: 99%

Axial Orientation of Co-Crystalline Phases of Poly(2,6-Dimethyl-1,4-Phenylene)Oxide Films

et al. 2020

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Films exhibiting co-crystalline (CC) phases between a polymer host and low-molecular-mass guest molecules are relevant for many applications. As is usual for semi-crystalline polymers, axially oriented films can give relevant information on the crystalline structure, both by Wide Angle X-ray diffraction fiber patterns and by polarized Fourier-transform infrared spectroscopy. Axially oriented CC phases of poly(2,6-dimethyl-1,4-phenylene)oxide (PPO) with 1,3,5-trimethylbenzene (mesitylene) can be simply obtained by the stretching of CC PPO films. In fact, due to the plasticization effect of this highly boiling guest, PPO orientation can occur in a stretching temperature range (170–175 °C) nearly 50 °C lower than that generally needed for PPO films (220–230 °C). This low stretching temperature range allows avoidance of polymer oxidation, as well as formation of the mesomorphic dense γ PPO phase. Axially oriented CC phases of PPO with toluene, i.e., with a more volatile guest, can be instead obtained by the stretching (in the same low temperature range: 170–175 °C) of CC PPO blend films with polystyrene.

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Section: Resultsmentioning

confidence: 99%

Axial Orientation of Co-Crystalline Phases of Poly(2,6-Dimethyl-1,4-Phenylene)Oxide Films

et al. 2020

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“…Centering of all the hk0 reflections along the meridian clearly indicates an orientation of the chain axes of the crystallites preferentially perpendicular to the film plane (c ⊥ orientation). This kind of orientation has been described for co-crystalline phases of s-PS [ 2 , 3 ] as well as of PPO, [ 9 ] while it is unprecedented for co-crystalline phases of PLLA. The degree of c ⊥ orientation of co-crystalline and α form phases, as evaluated from the azimuthal scans of their 020 and 110/200 reflections, is not far from f c = −0.3 for both phases.…”

Section: Resultsmentioning

confidence: 99%

“…The degree of orientation of the crystalline phase, f c , was calculated by using Herman’s orientation function [ 9 , 18 ]:

where cos 2 γ was calculated by the azimuthal distribution of the main reflection (110/200, at 2θ = 16.7°), for the EDGE patterns. Based on these assumptions, when f c is equal to 0, a random crystallite orientation occurs, while when f c is equal to –0.5 the c axes of all crystallites are perfectly perpendicular to the film plane.…”

Section: Methodsmentioning

confidence: 99%

“…Co-crystallization of polymers with suitable guest molecules can lead, without any stretching procedure, to films (even of high thickness) with high degrees of crystal phase orientation. In fact, planar and uniplanar orientations, i.e., the preferential orientations of a crystal axis or a crystal plane with respect to the film plane, can be easily achieved [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ]. Both planar and uniplanar orientations have been obtained for two commercial polymers: syndiotactic polystyrene (s-PS) [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ] and poly(2,6-dimethyl-1,4-phenylene ether) (PPO) [ 8 , 9 ] not only for their co-crystalline forms but also for the corresponding nanoporous-crystalline phases, as produced by guest removal [ 10 ].…”

Section: Introductionmentioning

confidence: 99%

“…In fact, planar and uniplanar orientations, i.e., the preferential orientations of a crystal axis or a crystal plane with respect to the film plane, can be easily achieved [1][2][3][4][5][6][7][8][9][10][11]. Both planar and uniplanar orientations have been obtained for two commercial polymers: syndiotactic polystyrene (s-PS) [1][2][3][4][5][6][7] and poly(2,6-dimethyl-1,4-phenylene ether) (PPO) [8,9] not only for their co-crystalline forms but also for the corresponding nanoporouscrystalline phases, as produced by guest removal [10].…”

Section: Introductionmentioning

confidence: 99%

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c-Perpendicular Orientation of Poly(ʟ-lactide) Films

et al. 2021

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Poly(ʟ-lactide) (PLLA) films, even of high thickness, exhibiting co-crystalline and crystalline α phases with their chain axes preferentially perpendicular to the film plane (c⊥ orientation) have been obtained. This c⊥ orientation, unprecedented for PLLA films, can be achieved by the crystallization of amorphous films as induced by low-temperature sorption of molecules being suitable as guests of PLLA co-crystalline forms, such as N,N-dimethylformamide, cyclopentanone or 1,3-dioxolane. This kind of orientation is shown and quantified by two-dimensional wide-angle X-ray diffraction (2D-WAXD) patterns, as taken with the X-ray beam parallel to the film plane (EDGE patterns), which present all the hk0 arcs centered on the meridian. PLLA α-form films, as obtained by low-temperature guest-induced crystallization, also exhibit high transparency, being not far from those of the starting amorphous films.

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Hydrogen Bonded Dimer of an Alcohol with the Derived Carboxylic Acid Triggering their Sorption by Nanoporous‐crystalline PPO Films

Nagendra

Cozzolino

Acocella

et al. 2023

Chemistry A European J

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Films exhibiting nanoporous‐crystalline (NC) phases of poly(2,6‐dimethyl‐1,4‐phenylene) oxide (PPO), which are highly effective to absorb apolar organic guest molecules, are also able to absorb polar molecules (like alcohols and carboxylic acids) but only from concentrated organic solutions. NC PPO films, which do not absorb alcohols and carboxylic acids from diluted aqueous solutions, exhibits a huge uptake (even above 30wt%) of benzyl alcohol (BAL) and benzoic acid (BA), if BA is obtained by spontaneous room temperature oxidation of BAL in aqueous solution. This phenomenon is rationalized by an easy uptake, mainly by the PPO intrahelical crystalline empty channels, of a BAL/BA 1/1 hydrogen‐bonded dimer. This huge uptake of BAL/BA dimer by NC PPO films, which is also fast for films exhibiting the orientation of the crystalline helices perpendicular to the film plane (c^ orientation), can be exploited for purification of water from BAL, when present in traces. High and fast sorption of a hydrogen bonded dimer and negligible sorption of the two separate compounds is possibly unprecedented for absorbent materials.

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Nanoporous-crystalline films of PPO with parallel and perpendicular polymer chain orientations

Cited by 36 publications

References 83 publications

Axial Orientation of Co-Crystalline Phases of Poly(2,6-Dimethyl-1,4-Phenylene)Oxide Films

Axial Orientation of Co-Crystalline Phases of Poly(2,6-Dimethyl-1,4-Phenylene)Oxide Films

c-Perpendicular Orientation of Poly(ʟ-lactide) Films

Hydrogen Bonded Dimer of an Alcohol with the Derived Carboxylic Acid Triggering their Sorption by Nanoporous‐crystalline PPO Films

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