Structure of Polymer Single Crystals

Lotz, Bernard; Wittmann, J. C.

doi:10.1002/9783527603978.mst0134

Cited by 8 publications

(9 citation statements)

References 243 publications

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“…The thickness of individual lamellae is around 9–10 nm, as was obtained from the measurement of the cross-section trace shown in Figure 5 B, which is typical for linear PCL SCs [ 117 ]. A similar thickness value was also detected for monolamellar SC presented in Figure 5 G. Defined as one of the most important types of defect in polymer structures [ 118 ], the screw dislocations found in both PCL-containing linear and branched architectures [ 110 , 112 , 117 , 119 ] forbid the crystallographic coherence between successive layers, which give rise to spectacular rotations that are always associated with a pyramidal habit, as can be seen in the bottom-right corner of Figure 5 A. These screw dislocations have been attributed to different factors [ 120 ], but as structural factors, the non-planarity of the ester group carbonyl in the PCL repeating units and the effect of chain ends [ 118 ] (especially bulky ones) have been cited as the main reasons.…”

Section: Resultssupporting

confidence: 72%

3,4-Ethylenedioxythiophene (EDOT) End-Group Functionalized Poly-ε-caprolactone (PCL): Self-Assembly in Organic Solvents and Its Coincidentally Observed Peculiar Behavior in Thin Film and Protonated Media

Bendrea¹,

Cianga²,

Ailiesei³

et al. 2021

Polymers

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End-group functionalization of homopolymers is a valuable way to produce high-fidelity nanostructured and functional soft materials when the structures obtained have the capacity for self-assembly (SA) encoded in their structural details. Herein, an end-functionalized PCL with a π-conjugated EDOT moiety, (EDOT-PCL), designed exclusively from hydrophobic domains, as a functional “hydrophobic amphiphile”, was synthesized in the bulk ROP of ε-caprolactone. The experimental results obtained by spectroscopic methods, including NMR, UV-vis, and fluorescence, using DLS and by AFM, confirm that in solvents with extremely different polarities (chloroform and acetonitrile), EDOT-PCL presents an interaction- and structure-based bias, which is strong and selective enough to exert control over supramolecular packing, both in dispersions and in the film state. This leads to the diversity of SA structures, including spheroidal, straight, and helical rods, as well as orthorhombic single crystals, with solvent-dependent shapes and sizes, confirming that EDOT-PCL behaves as a “block-molecule”. According to the results from AFM imaging, an unexpected transformation of micelle-type nanostructures into single 2D lamellar crystals, through breakout crystallization, took place by simple acetonitrile evaporation during the formation of the film on the mica support at room temperature. Moreover, EDOT-PCL’s propensity for spontaneous oxidant-free oligomerization in acidic media was proposed as a presumptive answer for the unexpected appearance of blue color during its dissolution in CDCl3 at a high concentration. FT-IR, UV-vis, and fluorescence techniques were used to support this claim. Besides being intriguing and unforeseen, the experimental findings concerning EDOT-PCL have raised new and interesting questions that deserve to be addressed in future research.

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Section: Resultssupporting

confidence: 72%

3,4-Ethylenedioxythiophene (EDOT) End-Group Functionalized Poly-ε-caprolactone (PCL): Self-Assembly in Organic Solvents and Its Coincidentally Observed Peculiar Behavior in Thin Film and Protonated Media

Bendrea¹,

Cianga²,

Ailiesei³

et al. 2021

Polymers

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“…12 This suggests that the formation of nanofibrils could occur through an aggregation across a "fold surface", which is assumed to form at both sides of each polyalanine domain 12 and resembles solution grown polymer single crystals. 57 Contrast Variation of Amorphous Fractions. Spider dragline silk is readily absorbing water by its amorphous network which results in a breaking of the hydrogen-bonded network 39 and an increase in kinetic freedom of the chains.…”

Section: Resultsmentioning

confidence: 99%

Nanofibrillar Structure and Molecular Mobility in Spider Dragline Silk

et al. 2005

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Nephila edulis dragline silk has been investigated by elastic and quasielastic neutron scattering techniques. The data support a three-phase model of nanofibrils, composed of crystalline and short-range order domains, which are embedded in an amorphous matrix of random protein chains. A meridional superlattice peak in D 2O-exchanged silk is tentatively assigned to a smectic β-sheet structure in the short-range order domains. Water is absorbed preferentially by the amorphous matrix. The onset of molecular mobility in hydrated silk at about 200 K is attributed to water molecules, which move on the picosecond time scale. Coexisting slower motions on the nanosecond time scale are possibly due to polymer chain dynamics. Native silk at rest appears to behave similar to a glass below 300 K.

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“…A similar situation has been observed in the case of polyethylene where various fold surfaces have been observed ({0 0 1}, {1 0 1}, {2 0 1}, and{3 0 1}), depending on the crystallization conditions. [48][49][50] The above-mentioned sequence of fold surfaces corresponds to an increasing tilt angle, i.e., a reduced packing density of the polymer stems at the fold surface. The occurrence of different fold surfaces with relatively high tilt angles is possibly a consequence of the stress exerted by chain folding on the crystalline packing of Rr-P3HT chains.…”

Section: Discussion 32a Effect Of M W On the Interconnectivity Betwee...mentioning

confidence: 99%

Molecular Weight Dependence of Chain Packing and Semicrystalline Structure in Oriented Films of Regioregular Poly(3-hexylthiophene) Revealed by High-Resolution Transmission Electron Microscopy

2009

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The semicrystalline structure of regioregular head-to-tail- (HT-) coupled poly(3-hexylthiophene-2,5-diyl) (Rr-P3HT) thin films grown by directional epitaxial solidification (DES) has been studied by high-resolution transmission electron microscopy (HR-TEM). A 10-fold increase of the weight-average molecular weight of the Rr-P3HT leads to several major structural changes: (i) an increase of the fluctuations of the lamellar thickness while preserving the average length of the polymer stems in the crystalline domains; (ii) an increase of the disorder in the crystalline packing of Rr-P3HT chains; (iii) an enhanced interconnectivity between crystalline lamellae via tie-crystallites and tie-chains; (iv) for M w ≥ 18.8 kDa equiv PS, preferential tilt angles of the polymer chains in the crystalline lamellae. Similar to stiff-chain polymers like poly(etheretherketone), the concomitant increase of the interchain distance (i.e., the a parameter in the unit cell) and the tilting of Rr-P3HT chains in the crystalline lamellae are attributed to chain folding exerting stress on the crystal packing because of the stiffness of comb-shaped Rr-P3HT chains.

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Structure of Polymer Single Crystals

Cited by 8 publications

References 243 publications

3,4-Ethylenedioxythiophene (EDOT) End-Group Functionalized Poly-ε-caprolactone (PCL): Self-Assembly in Organic Solvents and Its Coincidentally Observed Peculiar Behavior in Thin Film and Protonated Media

3,4-Ethylenedioxythiophene (EDOT) End-Group Functionalized Poly-ε-caprolactone (PCL): Self-Assembly in Organic Solvents and Its Coincidentally Observed Peculiar Behavior in Thin Film and Protonated Media

Nanofibrillar Structure and Molecular Mobility in Spider Dragline Silk

Molecular Weight Dependence of Chain Packing and Semicrystalline Structure in Oriented Films of Regioregular Poly(3-hexylthiophene) Revealed by High-Resolution Transmission Electron Microscopy

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