Crystallization behavior of polyethylene oxide/para-nitroaniline microdispersed composites

Saujanya, C.; Radhakrishnan, S.

doi:10.1002/(sici)1097-4628(19970808)65:6<1127::aid-app8>3.0.co;2-m

Cited by 13 publications

(12 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Such an interaction is sufficient to cause displacement of MNA molecules, during crystallization, from their usual positions in the crystal lattice. We have observed similar types of interaction in the PNA/PEO guest/host system,31 where the complex formed between PNA and PEO was confirmed by melting points and phase diagram. In pure MNA, which has a orthorhombic crystalline structure, the planes of benzene rings are parallel to the c‐axis, with all the nitro groups pointing in the same direction 32.…”

Section: Resultssupporting

confidence: 70%

Polymer mediated growth and morphology in MNA/PMMA guest/host microdispersed composites

Saujanya

Pathak

Radhakrishnan

2001

J of Applied Polymer Sci

Self Cite

View full text Add to dashboard Cite

ABSTRACT:The structure and morphology in the meta-nitroaniline (MNA) dispersed poly(methyl methacrylate) (PMMA) guest/host system was investigated with respect to composition and different techniques of crystallization. Large changes in the intensities of various X-ray diffraction peaks were observed for both solution grown (SC) and melt crystallized (MC) MNA/PMMA composite films. However, in the former case, the peak corresponding to (060) reflection had maximum intensity, while in the latter, the peak corresponding to (112) reflection was most prominent. At low concentrations, the films appeared to be amorphous and transparent, but electron diffraction studies revealed small ordered domains. Both solution and melt grown MNA/PMMA films contained two types of crystallites having different structures: one having the original orthorhombic structure (a ϭ 6.51 Å, b ϭ 19.35 Å, c ϭ 5.07 Å) of bulk MNA, while the other crystallized in new monoclinic phase with a ϭ 13.0 Å, b ϭ 19.35 Å, c ϭ 10.15 Å, and ␤ ϭ 64°. The presence of the new structure that formed could be due to a formation of complex between PMMA and MNA. This complex formation and new structure was further confirmed by differential scanning calorimeter (DSC) and infrared analysis (IR).

show abstract

Section: Resultssupporting

confidence: 70%

Polymer mediated growth and morphology in MNA/PMMA guest/host microdispersed composites

Saujanya

Pathak

Radhakrishnan

2001

J of Applied Polymer Sci

Self Cite

View full text Add to dashboard Cite

show abstract

“…5) show a series of crystalline diffraction peaks with the scattering angles of the main ones observed at 2y = 19.01 and 2y = 23.11 in a very good agreement with those reported in the literature. [116][117][118][119] The diffractograms of the nanocomposites showed peaks that correspond to crystalline PEO only for polymer concentrations higher than B70 wt%. The absence of these diffraction peaks from the data of the nanocomposites with lower PEO content indicates that the intercalated polymer as well as the chains that are in close proximity to the inorganic surfaces are amorphous; it is only the excess polymer outside the completely filled galleries and away from the outside walls of the inorganic particles that is able to crystallize.…”

Section: Hydrophilic Linear Peomentioning

confidence: 99%

Effects of nanoscopic-confinement on polymer dynamics

Chrissopoulou

Anastasiadis

2015

Soft Matter

View full text Add to dashboard Cite

The static and dynamic behavior of polymers in confinement close to interfaces can be very different from that in the bulk. Among the various geometries, intercalated nanocomposites, in which polymer films of ∼1 nm thickness reside between the parallel inorganic surfaces of layered silicates in a well-ordered multilayer, offer a unique avenue for the investigation of the effects of nanoconfinement on polymer structure and dynamics by utilizing conventional analytical techniques and macroscopic specimens. In this article, we provide a review of research activities mainly in our laboratory on polymer dynamics under severe confinement utilizing different polymer systems: polar and non-polar polymers were mixed with hydrophilic or organophilic silicates, respectively, whereas hyperbranched polymers were studied in an attempt to probe the effect of polymer-surface interactions by altering the number and the kinds of functional groups in the periphery of the branched polymers. The polymer dynamics was probed by quasielastic neutron scattering and dielectric relaxation spectroscopy and was compared with that of the polymers in the bulk. In all cases, very local sub-Tg processes related to the motion of side and/or end groups as well as the segmental α-relaxation were identified with distinct differences recorded between the bulk and the confined systems. Confinement was found not to affect the very local motion in the case of the linear chains whereas it made it easier for hyperbranched polymers due to modifications of the hydrogen bond network. The segmental relaxation in confinement becomes faster than that in the bulk, exhibits Arrhenius temperature dependence and is observed even below the bulk Tg due to reduced cooperativity in the confined systems.

show abstract

“…The 1D WAXD profile of PEO and PEO–NaI is shown in Figure S6. The PEO exhibits two sharp peaks at about 15.06 and 18.32°, corresponding to ordered PEO with a typical monoclinic unit cell structure of the (111) or (120) and (112) crystal planes, respectively. , The 1D WAXD profile of PEO–NaI shows the same peak positions as PEO, implying the absence of polymer salt complexes . The absence of peaks pertaining to NaI salt in the composites also indicates the complete dissolution of salt in the polymer matrix .…”

Section: Resultsmentioning

confidence: 92%

Polymer–Ion Interaction Weakens the Strain-Rate Dependence of Extension-Induced Crystallization for Poly(ethylene oxide)

Tian

Ali

et al. 2016

Langmuir

View full text Add to dashboard Cite

The crystallization of poly(ethylene oxide) (PEO)-sodium iodine (NaI) composites is investigated by differential scanning calorimetry (DSC), extensional rheology, and in situ small-angle X-ray scattering (SAXS) with the aim of demonstrating versatile roles played by polymer-ion interactions. In the isothermal quiescent crystallization process, a decrease in the crystal growth rate is observed for PEO-NaI and is attributed to slow chain movement caused by the coordination between cations and polymer. In situ SAXS on extensional flow-induced crystallization (FIC) exhibits enhanced kinetics and orientation for both PEO and PEO-NaI with increasing strain rate. However, an overall weaker strain-rate dependence of FIC is observed for PEO-NaI, which can be interpreted as a synergistic consequence of promoted nucleation under flow and impeded crystal growth by polymer-ion interaction. A possible microscopic mechanism is proposed to account for the experimental observation based on the formation of transient cross-linking points in PEO-NaI and their influence on the entanglement network of polymer under various flow fields. The disclosed strain-rate dependence and various ion effects on the behavior of PEO-salt composites contribute to a comprehensive understanding of polymer-ion solid polyelectrolytes.

show abstract

Crystallization behavior of polyethylene oxide/para-nitroaniline microdispersed composites

Cited by 13 publications

References 9 publications

Polymer mediated growth and morphology in MNA/PMMA guest/host microdispersed composites

Polymer mediated growth and morphology in MNA/PMMA guest/host microdispersed composites

Effects of nanoscopic-confinement on polymer dynamics

Polymer–Ion Interaction Weakens the Strain-Rate Dependence of Extension-Induced Crystallization for Poly(ethylene oxide)

Contact Info

Product

Resources

About