Optically Active Polyethers. 2. Atomic Force Microscopy of Melt-Crystallized Poly(epichlorohydrin) Enantiomers and Their Equimolar Blend

Singfield, Kathy L.; Klass, J. M.; Brown, G. R.

doi:10.1021/ma00128a006

Cited by 58 publications

(72 citation statements)

References 13 publications

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“…There are two possibilities: One is that the spirals really exist, which can be confirmed by SEM or AFM observation of the surface morphology [59]. The other is due to the artifact of polarized light.…”

Section: Organization Of Twisted Lamellae In Banded Spherulitesmentioning

confidence: 91%

Organization of Twisting Lamellar Crystals in Birefringent Banded Polymer Spherulites: A Mini-Review

Zhang

et al. 2017

Crystals

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Abstract:In this mini-review, we summarize the evidences of lamellar twisting in the birefringent banded polymer spherulites demonstrated by various characterization techniques, such as polarized optical microscopy, real-time atomic force microscopy, micro-focus wide angle X-ray diffraction, etc. The real-time observation of lamellar growth under atomic force microscopy unveiled the fine details of lamellar twisting and branching in the banded spherulites of poly(R-3-hydroxybutyrate-co-17 mol % R-3-hydroxyhexanoate). Organization of the twisting lamellar crystals in the banded spherulites was revealed as well. The lamellar crystals change the orientation via twisting rather than the macro screw dislocations. In fact, macro screw dislocation provides the mechanism of synchronous twisting of neighboring lamellar crystals. The driving force of lamellar twisting is attributed to the anisotropic and unbalanced surface stresses. Besides molecular chirality, variation of the growth axis and the chemical groups on lamellar surface can change the distribution of the surface stresses, and thus may invert the handedness of lamellar twisting. Thus, based on both experimental results and physical reasoning, the relation between crystal chirality and chemical molecular structures has been suggested, via the bridge of the distribution of surface stresses. The factors affecting band spacing are briefly discussed. Some remaining questions and the perspective of the topic are highlighted.Keywords: banded polymer spherulite; ringed spherulite; lamellar twisting; organization of lamellar crystals; surface stresses; chirality When crystallized from quiescent melt or concentrated solution, polymer chains usually form spherulites consisted of multiple lamellar crystals radiating from the spherulite center. Observed under polarized optical microscope (POM), a spherulite shows the characteristic Maltese-cross extinction. Besides the Maltese cross, some spherulites demonstrate alternative bright and dark bands under POM. These spherulites are termed as banded spherulites or ringed spherulites. The band structure with different light intensities may result from different thicknesses or different birefringences but similar thickness. In the former case, the bands are due to the periodical modulation of sample thickness and there is no variation of refractive index in the spherulite. These nonbirefringent banded spherulites have been observed in some polymer single crystals formed from thin melt films [1] or solutions [2] and are reviewed by Li et al. [3] in this special issue. In the latter case, the birefringent bands can result from the wavy bending growth or twisting growth of crystals. The wavy bands have been reported in sheared liquid crystals [4,5], which do not form spherulites under the condition. In this mini-review, we focus on the birefringent banded spherulites, which consist of synchronously twisted lamellar crystals. The organization of the twisted lamellar crystals in the banded spherulites and the driving force for lamell...

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Section: Organization Of Twisted Lamellae In Banded Spherulitesmentioning

confidence: 91%

Organization of Twisting Lamellar Crystals in Birefringent Banded Polymer Spherulites: A Mini-Review

Zhang

et al. 2017

Crystals

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“…It can be seen that the edge-on and the flat-on lamellae are alternately generated to give rise to the periodic concentric rings observed in PLM and RLM. For a thin film crystallized with a free surface, the unrestrained lamellae generated periodic topographical variations [56,57] as they are developed along the radial direction of the banded spherulite. In Fig.…”

Section: Origin Of Ptt Banded Spherulite Formationmentioning

confidence: 99%

Effects of crystallization behavior on morphological change in poly(trimethylene terephthalate) spherulites

Chuang

Hong

Chuah

2004

Polymer

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“…44,63 In the case of polymers with chiral structures, it is considered that the chirality of the main chain is the origin of lamella twisting and that it is strongly related to the handedness of lamella twisting. 64,65 Furthermore, lamella twisting has also been Application of Microbeam X-ray Scattering to Polymeric Material found in some crystalline/amorphous polymer blend systems that have neither chirality nor c-axis tilting in a crystal. In this section, we focus on the twisting manner in crystalline/amorphous polymer blend system.…”

Section: Inhomogeneous Crystalline Morphologymentioning

confidence: 99%

Application of Microbeam Small- and Wide-angle X-ray Scattering to Polymeric Material Characterization

Nozue

Shinohara

Amemiya

2007

Polym J

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ABSTRACT:With the recent development of an X-ray source, focusing optics, and X-ray detectors, microbeam Xray scattering techniques have been well established and widely applied to the characterization of polymeric materials. Microbeam X-ray scattering is a unique and powerful tool that provides abundant information on local structures, such as the spatial inhomogeneity of materials and the structural change at a local position. Furthermore, by combining microbeam small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS), the observable spatial scale range is from several to several hundred Å , which is the most important scale range in the hierarchical structure analyses of polymers. In this review, the representative applications of microbeam X-ray scattering to polymer crystallization, spatial inhomogeneity analyses, stress transfer under external field and the microphase separated structure analyses in block copolymer systems are introduced. [doi:10.1295/polymj.PJ2007077] KEY WORDS Microbeam Small-and Wide-angle X-ray Scattering / Polymer Characterization / X-Ray scattering techniques are widely applied to the observation of various polymer structures. X-Ray scattering is mainly classified into small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS), depending on the scattering angle. As is easily understood by using the Bragg formula ( ¼ 2d sin ), when the scattering angle 2 decreases, scattering reflects a large structure. SAXS, which is X-ray scattering at small angle (< 2, 3) region, provides information on nanostructures in a size range of several to several ten nanometers. In the field of polymeric materials, SAXS is typically applied to obtaining information on crystalline lamella stacking structures, 1,2 various microphase separated structures in block copolymer systems, 3,4 and organic-inorganic composite structures. 5,6 On the other hand, WAXS is typically applied to obtaining information on sub-nanometerscale structures, such as crystal packing and amorphous structures.To determine the structural characteristics of polymeric materials in detail, it is also very important to understand the formation and/or deformation mechanisms of such materials. Although X-ray scattering experiments were limited to the static measurements in laboratory X-ray sources until early 1980s, the advent of a synchrotron X-ray source and the development of X-ray detectors 7-13 have enabled us to observe a one-or two-dimensional scattering pattern within a second, making it possible to perform timeresolved X-ray scattering measurements for various structural changes, such as crystallization, 14-17 structural changes due to deformation [18][19][20][21][22][23] and phase transition due to temperature change. [24][25][26] While many polymeric materials exhibit spatial inhomogeneity on a micrometer scale, conventional X-ray scattering techniques provide the information that is spatially averaged over more than hundreds micrometer of the sample area irradiated by X-ray beam. Structural inmhom...

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Optically Active Polyethers. 2. Atomic Force Microscopy of Melt-Crystallized Poly(epichlorohydrin) Enantiomers and Their Equimolar Blend

Cited by 58 publications

References 13 publications

Organization of Twisting Lamellar Crystals in Birefringent Banded Polymer Spherulites: A Mini-Review

Organization of Twisting Lamellar Crystals in Birefringent Banded Polymer Spherulites: A Mini-Review

Effects of crystallization behavior on morphological change in poly(trimethylene terephthalate) spherulites

Application of Microbeam Small- and Wide-angle X-ray Scattering to Polymeric Material Characterization

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