Uniplanar Orientations and Guest Exchange in PPO Cocrystalline Films

Rizzo, Paola; Ianniello, Graziella; Longo, Simona; Guerra, Gaetano

doi:10.1021/ma400313x

Cited by 23 publications

(21 citation statements)

References 66 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…c), to the best of our knowledge, have not been reported in the literature. The high thickness of the considered plates and the permanence of the altered reflection intensity ratios, after axial stretching at high strain (Figure 3Bc), clearly rule out the possible hypothesis that this anomalous reflection intensities could be because of some kind of uniplanar orientation of the crystalline phase, of the kind often observed for thermoplastic polymers when subjected to biaxial stretching or solution casting …”

Section: Resultsmentioning

confidence: 95%

Crystallinity and crystalline phase orientation of poly(1,4-cis-isoprene) fromHevea brasiliensisandTaraxacum kok-saghyz

Musto

Barbera

Maggio

et al. 2016

Polym. Adv. Technol.

Self Cite

View full text Add to dashboard Cite

Crystallization is studied for poly(isoprene-1,4-cis) from Hevea brasiliensis (natural rubber [NR]) and from taraxacum kok-saghyz, mainly by collecting wide-angle X-ray diffraction patterns after processing and stretching. Although rubber samples before stretching are generally fully amorphous, crystallization can be induced in NR samples by processing at room temperature under moderate pressure. This phenomenon is possibly associated with nucleation by saturated fatty acid components. For rubber samples being fully amorphous in the undeformed state, straininduced crystallization occurs only at high strain ratios (α > 4), leading to high degrees of crystalline phase orientation (f c > 0.9 for α = 5). Rubber samples presenting some crystallinity already in the unstretched state, on the contrary, reach much lower degrees of axial orientation, even for high strain ratios (f c < 0.7 for α = 5). These differences in crystallinity and in crystalline phase orientations produce large differences in stress-strain behavior of the rubber. By room temperature processing, the considered NR samples can also develop an unreported disordered crystalline modification, with low intensity of 120 and 121 reflections. This disordered crystalline modification, which is also maintained after axial stretching procedures, can rationalized by a structural disorder along the b axis, possibly associated with statistical sequences of A + TA À or A À T A + conformations for poly(isoprene-1,4-cis) chains. Copyright © 2016 John Wiley & Sons, Ltd.Keywords: poly(isoprene-1,4-cis); crystallinity; strain-induced crystallization INTRODUCTIONNatural rubber (NR) is the regular head-to-tail polymer essentially made by isoprene-1,4-cis units. [1][2][3][4] It is the most important rubber, with increasing worldwide consumption, that amounts at present to more than 12 million t/year.[5] At the origin of such a large commercial success are the NR outstanding properties: great strength [6,7] and tack [8][9][10] in the uncrosslinked state and in the crosslinked state, very high tensile strength [11,12] and crack growth resistance, both in static [13][14][15][16][17] and in fatigue [18][19][20][21][22][23][24] loading conditions. Beneficial for such NR properties is definitely the great mobility of the polymer chains that are usually amorphous at rest. However, also the ability of NR to crystallize plays a fundamental role. NR undergoes strain-induced crystallization (SIC) that is the rapid development of crystallization under straining. Many aspects of SIC have been reviewed, [25][26][27] and further works are continuously appearing, focused on the study of models, [28,29] crystallite structure, [30,31] segmental dynamics, [32] local strain response, [33] mechanism of deformation, [34] morphology, [35] orientation and deformation mechanisms, [36] crystallite melting temperature, [37] temperature dependence of the mechanical properties, [38] kinetics [36,39,40] and time [41] of crystallization, fatigue behavior, [42,43] effect of entanglements and endlinking n...

show abstract

Section: Resultsmentioning

confidence: 95%

Crystallinity and crystalline phase orientation of poly(1,4-cis-isoprene) fromHevea brasiliensisandTaraxacum kok-saghyz

Musto

Barbera

Maggio

et al. 2016

Polym. Adv. Technol.

Self Cite

View full text Add to dashboard Cite

show abstract

“…The relevance of crystalline phase orientations in polymer films is also related to their possible stability as a consequence of crystal phase transitions. Most of the achieved uniplanar orientations for cocrystalline phases of s-PS 24−29 and PPO 34 can be also maintained after guest-exchange procedures 25,34 as well as after crystal to crystal transitions. 24,25,28,29,31,72 The uniplanar orientation, as obtained for amorphous PLLA films by guest induced cocrystallization, can be fully maintained as a consequence of guest exchange procedures with suitable guest molecules.…”

Section: With Relative Intensities Intermediate Between Those Of Fullmentioning

confidence: 96%

“…32,33 As for PPO, two different kinds of uniplanar orientations have been recently obtained by cocrystallization, as induced by different guests in amorphous films. 34 In general, for polymeric materials, the effects of orientation on physical properties are strongly relevant: for instance, the extent to which it is possible to increase stiffness and strength find no parallel with other materials. 35 Moreover, crystalline phase orientation is particularly relevant for functional polymeric materials, when the functionality is mainly associated with crystalline phases, as for conductive 36 or ferroelectric 37 polymers.…”

Section: ■ Introductionmentioning

confidence: 99%

Poly(l-lactic acid): Uniplanar Orientation in Cocrystalline Films and Structure of the Cocrystalline Form with Cyclopentanone

et al. 2015

Self Cite

View full text Add to dashboard Cite

Guest molecules, like cyclopentanone (CPO), N,Ndimethylformamide (DMF) tetrahydrofuran (THF) and 1,3−dioxolane (DOL), which are able to cocrystallize with poly(L-lactic acid) (PLLA), can also generate high degree of crystalline phase orientation, by simple sorption in amorphous unoriented PLLA films. This crystalline phase orientation is defined as a ∥ c ∥ (a-parallel, c-parallel) because the ac plane of most crystallites is preferentially parallel to the film plane. This crystalline phase orientation, which is achieved without stretching even for high thickness films, is unprecedented for PLLA and can be maintained after suitable guest exchange procedures. The reported results confirm the recent hypothesis that cocrystallization with lowmolecular-mass guest molecules could be a common route for getting uniplanar orientations of polymer crystalline phases, even in the absence of stretching. Wide angle X-ray diffraction analyses of unoriented and oriented PLLA samples have allowed proposing the structure of the cocrystalline form of PLLA with CPO. In particular, four PLLA chains exhibiting the 10/7 helical conformation and 16 CPO guest molecules are packed according the space group P2 1 2 1 2 1 in an orthorhombic lattice with a = 1.61 nm, b = 1.26 nm, and c = 2.90 nm. The presence in PLLA cocrystalline structures of dense bc layers with close-packed polymer helices allows an easy rationalization of the observed uniplanar orientation. ■ INTRODUCTIONPolymeric cocrystalline forms, i.e. structures were a polymeric host and a low-molecular-mass guest are cocrystallized, although early recognized in literature, have been ignored for many decades. 1−15 Only in the last 2 decades have a few polymeric cocrystalline forms received attention in material science, mainly due to their ability to produce nanoporouscrystalline forms, 16−21 as a consequence of guest removal. 16,22,23 In the past decade, it has been also found that cocrystallization with suitable guest molecules of two commercial polymers: syndiotactic polystyrene (s-PS) and poly(2,6-dimethyl-1,4-phenylene ether) (PPO), can lead without any stretching procedure to high thickness f ilms (up to 200− 300 μm) with high degrees of different kinds of uniplanar orientations of the crystalline phases, i.e., with high degrees of parallelism of well-defined crystal planes with respect to the film plane. 24−34 In particular, for s-PS films, three different kinds of uniplanar orientations can be achieved by simple procedures involving cocrystallization in the presence of suitable guest molecules (solution crystallization, 24−26 solventinduced crystallization in amorphous samples, 27−30 or solventinduced recrystallizations of suitable crystalline films 31 ). The three observed uniplanar orientations correspond to the three simplest orientations of a high planar-density layer (formed by close-packed alternated enantiomorphous s-PS helices) with respect to the film plane. 32,33 As for PPO, two different kinds of uniplanar orientations have been recently obtained by cocrystallizat...

show abstract

“…The mechanism was shown in DBRs made of alternated layers of CA and poly (p‐phenylene oxide) (PPO) as active medium for sensing aromatic compounds . PPO is indeed well‐known for its remarkable sorption properties correlated to its crystallinity . The analytes intercalation in the structure brings to guest induced crystallization of the PPO layers[182a,d,e] inducing prominent changes in the refractive index and in the response kinetics.…”

Section: Applicationsmentioning

confidence: 99%

“…PPO is indeed well‐known for its remarkable sorption properties correlated to its crystallinity . The analytes intercalation in the structure brings to guest induced crystallization of the PPO layers[182a,d,e] inducing prominent changes in the refractive index and in the response kinetics. These last favor an easy recognition of very similar analytes in term of molecular size and polarity such as benzene and toluene, beside carbon tetrachloride and 1,2‐dichlorobenzene ( Figure ) .…”

Section: Applicationsmentioning

confidence: 99%

Advances in Functional Solution Processed Planar 1D Photonic Crystals

Lova

Manfredi

Comoretto

2018

Advanced Optical Materials

179

226

View full text Add to dashboard Cite

photonic states (PDOS), [2][3][4] which helps explaining the photoluminescence (PL) changes of materials when embedded in the PhC structure.Traditionally, PhCs have been made carving bulky inorganic dielectrics or sem iconductors. These structures are still a hot topic in photonics for optical fibers, light emitting diodes (LEDs), sensors, photo voltaic devices, lasers, discrete and integrated optical components, lightening, and quantum computing. [6] However, new solution processable photoactive materials (e.g., organic semiconductors, quantum dots, hybrid perovskites, and selfassem bling supramolecular systems) stimulated the development of PhCs grown with organic and colloidal materials by solution and melt processes. [7] Among PhCs, distributed Bragg reflectors (DBRs) are cur rently the most interesting owing to their planar structure which generates a simple optical response that represents a playground to understand deep physical concepts, as described in Sections 2.4 and 4. DBRs are indeed made of alternated thin films of different dielectric materials. This simplicity makes them the only PhCs that can take advantage of large area growths (see Section 3.1). [8] Such fabrication methods are unconceivable with bulky inorganic DBRs and might reduce processing costs and enhance customizability, also on industrial scale, thus adding unprecedented market opportunities. Figure 1 illustrates the evolution and fabrications of solution and melt processed DBRs. The top of the Figure displays three wellknown natural DBRs belonging to animal and plant reigns: the mother of pearl, [9] the Panamanian Tortoise beetle exoskel eton, [10] and the Pollia Condensata skin, [11] whose growth is driven by the thermodynamics of spinodal phase separation. [12] The interest in these natural structures leads to their emulation until the development of solutionbased fabrication methods for flexible synthetic DBRs made of polymers and inorganic nanoparticles (Figure 1). At the base of Figure 1, we also show some applications arose only in the last decades. From left to right: the use of DBRs in functional architecture, in enhance ment of photon absorption for photovoltaic cells and modules, emission control, lasing, and sensing. [7c,13] In this paper we will first briefly review the properties of DBRs and then focus on the reasons that guided the research toward new solutionbased and largearea fabrications, describing current processes used both at the laboratory and largearea scales. We will then review the main applications of these structures comparing the performances of mesoporous inorganic and polymer devices. An overview on the properties and applications of polymer and inorganic planar 1D photonic crystals fabricated from solution is provided here. In the last decades, photonic crystals became technologically relevant for light management, photovoltaics, sensing, and lasing. Such structures are traditionally produced by lithographic and vacuum techniques, but the need to reduce costs and to scale-up the fabrication have lea...

show abstract

Uniplanar Orientations and Guest Exchange in PPO Cocrystalline Films

Cited by 23 publications

References 66 publications

Crystallinity and crystalline phase orientation of poly(1,4-cis-isoprene) fromHevea brasiliensisandTaraxacum kok-saghyz

Crystallinity and crystalline phase orientation of poly(1,4-cis-isoprene) fromHevea brasiliensisandTaraxacum kok-saghyz

Poly(l-lactic acid): Uniplanar Orientation in Cocrystalline Films and Structure of the Cocrystalline Form with Cyclopentanone

Advances in Functional Solution Processed Planar 1D Photonic Crystals

Contact Info

Product

Resources

About