X‐ray studies of crystallization of poly(2,6‐dimethyl‐1,4‐phenylene oxide) on swelling in certain systems

Abstract

The processes of swelling and crystallization of poly(2,6-dinicthyl-l,4-phenylene oxide) (PPO) in polymer-swelling agent systems as well as the structures obtained were investigated by means of wide-angle x-ray scattering. As the swelling agents we used mainly decalin and also or-pinen and tetralin. The effect of the swelling parameters of PPO in decalin on the possibilities of obtaining various polymcr structures was studied. The role played by a low-molecular substance in the process of the formation of crystalline structure in PPO was examined. I t was found that the crystallization mechanism depends mainly on the chemical propertics of the polymer and the s~velling agent,. Rontgenographische Untersuchurig der Kristallisation von Poly(2,6-dimethyl-I,d-phenylen~len-oxid) wulzrend des Quellungsprozesses in bestimmten SystemenDie Quellungs-und Kristallisationsprozesse von Poly(2,6-dimethyl-1,4-phenyleiioxid) (PPO) in Polymcr-Quellungsmittel-Systemen sowic die erhaltenen Strulituren wurden mittels Rontgenweitwinkelstreuung untersucht. Als Quellungsmittel wurden vorwiegend Decalin sowie a-Piricn und Tetralin eingesetzt. Iler EinfluS der Quellungsbedingungen in Decalin auf die Moglichkeit, verschiedene Polymcrstrulcturen zu erhalten, wurde gepriift. Die Rolle niedermolekularer Substanz im ProzeS der Rildung kristalliner Strultturen in PPO wurde untersucht. Es wurde gefunden, daS der Verlauf der Kristallisation vorwiegcnd voii den chemischeri Eigenschaften des Polymers und des Qnellungsmittels ab hangt . Penmzenozpa@ultec~oe uccneaoeame ~pucmannuaayuu nonu(2,6-au.uem~n-l,4-~enuneno~cu~a) e npoyecce t l a 6 y x a~u~ e onpeaeJceltnux cucme.uax

Advanced materials based on polymer cocrystalline forms

“…Polymeric cocrystalline forms are quite common for several regular and stereoregular polymers, such as, for example, isotactic21–23 and syndiotactic polystyrene (s‐PS),24–40 syndiotactic poly‐ p ‐methyl‐styrene,41–47 syndiotactic poly‐ m ‐methyl‐styrene,48, 49 syndiotactic poly‐ p ‐chloro‐styrene,50 syndiotactic poly‐ p ‐fluoro‐styrene,51 polyethyleneoxide,52–55 poly(muconic acid),56, 57 polyoxacyclobutane,58 poly(vinylidene fluoride),59, 60 syndiotactic polymethylmethacrylate,61–63 isotactic poly‐4‐methyl‐1‐pentene,64 or poly(2,6‐dimethyl‐1,4‐phenylene ether) (PPO) 65–68…”

“…For instance, the methylene chloride guest is completely removed after few hours of air drying at room temperature. PPO cocrystalline forms with less volatile guests, such as decahydronaphthalene,68 tetrahydronaphthalene,68 or α‐pinene,66–68 are instead extremely stable and can be also obtained as single crystals 66, 67…”

Molecular Features Behind Formation of α or β Co-Crystalline and Nanoporous-Crystalline Phases of PPO

“…In particular, two completely different classes of co-crystalline (CC) forms with low-molecular-mass guest molecules can be obtained. The CC forms of Class i are formed only with a few specific guests (α-pinene, tetralin, and decalin), exhibit regular polymer helices, and give rise to highly ordered crystalline phases ( Barrales-Rienda and Fatou, 1971 ; Horikiri, 1972 ; Hurek and Turska, 1984 ; Tarallo et al, 2012 ). The CC forms of Class ii are instead formed with many guests and exhibit a different chain conformations and less ordered crystalline phases ( Daniel et al, 2011 ; Nagendra et al, 2019 ; Golla et al, 2020a ; Alentiev et al, 2021 ).…”

“…After guest removal, the CC phases of Class i become amorphous ( Barrales-Rienda and Fatou, 1971 ; Horikiri, 1972 ; Hurek and Turska, 1984 ; Tarallo et al, 2012 ), while the CC phases of Class ii can produce two different nanoporous crystalline (NC) forms, i.e., crystalline forms with a density lower than that of the corresponding amorphous phase. These NC forms were also named α and β because they maintain wide-angle x-ray diffraction (WAXD) patterns similar to those of the corresponding CC forms ( Nagendra et al, 2019 ).…”

Calorimetric Investigation of the Phase Behaviour of the System Poly(2,6‐Dimethyl‐1,4‐Phenyleneoxide)‐Antracene

“…It is reflected in the high glass transition temperature (T ) 9 ' . Addition of a solvent however promotes the crystallization of PPO(')(2)- (4). The main reason for the increase in the rate of crystallization in presence of a solvent is the difference between the decrease of the melting point ( l m and the decrease of T with increasing solvent contend5).…”