Glass transition and aging of the rigid amorphous fraction in polymorphic poly(butene-1)

Wang, Wei; Fenni, Seif Eddine; Ma, Zhe; Righetti, Maria Cristina; Cangialosi, Daniele; Lorenzo, Maria Laura Di; Cavallo, Dario

doi:10.1016/j.polymer.2021.123830

Cited by 6 publications

(8 citation statements)

References 63 publications

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“…That is, the observed endothermic peaks below T a = 80 °C correspond to the enthalpic overshoot as a physically aged glass undergoes the glass transition (this peak is shadowed in purple in Figure B). Moreover, in cyan color, at temperatures between T a = 80 and 150 °C, the overshoot due to the physical aging is no longer visible, and instead, a sharp bell-shaped endotherm associated with the melting process of the crystallites formed during the isothermal steps is observed. − …”

Section: Resultsmentioning

confidence: 99%

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Unraveling the Influence of the Preexisting Molecular Order on the Crystallization of Semiconducting Semicrystalline Poly(9,9-di-n-octylfluorenyl-2,7-diyl (PFO)

et al. 2022

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Understanding the complex crystallization process of semiconducting polymers is key for the advance of organic electronic technologies as the optoelectronic properties of these materials are intimately connected to their solid-state microstructure. These polymers often have semirigid backbones and flexible side chains, which results in a strong tendency to organize/ order in the liquid state. Therefore, crystallization of these materials frequently occurs from liquid states that exhibit�at least partial� molecular order. However, the impact of the preexisting molecular order on the crystallization process of semiconducting polymers� indeed, of any polymer�remained hitherto unknown. This study uses fast scanning calorimetry (FSC) to probe the crystallization kinetics of poly(9,9-di-n-octylfluorenyl-2,7-diyl (PFO) from both an isotropic disordered melt state (ISO state) and a liquidcrystalline ordered state (NEM state). Our results demonstrate that the preexisting molecular order has a profound impact on the crystallization of PFO. More specifically, it favors the formation of effective crystal nucleation centers, speeding up the crystallization kinetics at the early stages of phase transformation. However, samples crystallized from the NEM state require longer times to reach full crystallization (during the secondary crystallization stage) compared to those crystallized from the ISO state, likely suggesting that the preexisting molecular order slows down the advance in the latest stages of the crystallization, that is, those governed by molecular diffusion. The fitting of the data with the Avrami model reveals different crystallization mechanisms, which ultimately result in a distinct semicrystalline morphology and photoluminescence properties. Therefore, this work highlights the importance of understanding the interrelationships between processing, structure, and properties of polymer semiconductors and opens the door for performing fundamental investigations via newly developed FSC methodologies of such materials that otherwise are not possible with conventional techniques.

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Section: Resultsmentioning

confidence: 99%

“…Moreover, in cyan color, at temperatures between T a = 80 and 150 °C, the overshoot due to the physical aging is no longer visible, and instead, a sharp bell-shaped endotherm associated with the melting process of the crystallites formed during the isothermal steps is observed. 32 − 34 …”

Section: Resultsmentioning

confidence: 99%

Unraveling the Influence of the Preexisting Molecular Order on the Crystallization of Semiconducting Semicrystalline Poly(9,9-di-n-octylfluorenyl-2,7-diyl (PFO)

et al. 2022

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“…The size of the endothermic peak approaches zero at 40−50 °C for Form II and 100−110 °C for Form I (the latter figure extrapolated, since it is masked by secondary crystallization above 80 °C) (Figure 7). 72 The authors interpret these data in the frame of a structural recovery of glassy RAF and identify these two temperatures "as the upper limit of the RAF glass transition for the two polymorphs". 72 The origin of this striking difference in "glass transition temperatures" is assigned to strong hindrances of chain motions in the crystal of Form I (denser crystal packing, long-range threefold helix symmetry) that "cause tight constraints within the coupled amorphous phase".…”

Section: Stability and Generation Of The Raf Domainsmentioning

confidence: 99%

“…72 The authors interpret these data in the frame of a structural recovery of glassy RAF and identify these two temperatures "as the upper limit of the RAF glass transition for the two polymorphs". 72 The origin of this striking difference in "glass transition temperatures" is assigned to strong hindrances of chain motions in the crystal of Form I (denser crystal packing, long-range threefold helix symmetry) that "cause tight constraints within the coupled amorphous phase". By contrast, the looser crystal packing and lower symmetry of Form II helices [NB: 11 3 ] allow large movements of the chain backbone (even in the crystal, as documented by NMR analyses 73 ) and "decrease the stresses imparted to the amorphous parts linked with the crystals".…”

Section: Stability and Generation Of The Raf Domainsmentioning

confidence: 99%

“…By contrast, the looser crystal packing and lower symmetry of Form II helices [NB: 11 3 ] allow large movements of the chain backbone (even in the crystal, as documented by NMR analyses 73 ) and "decrease the stresses imparted to the amorphous parts linked with the crystals". 72 (The impact of crystal structure and density in iPBu is also discussed in SI5. )…”

Section: Stability and Generation Of The Raf Domainsmentioning

confidence: 99%

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Fold Surfaces of Polymer Crystals Are Nucleation Sites: The Link between Polymer Decoration, Secondary Crystallization, and the Rigid Amorphous Fraction (RAF)

Lotz

2023

Macromolecules

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The fold surfaces of polymer crystals may become suitable nucleating sites for uncrystallized material left over during the primary crystallization process. This “nucleation by the folds surface” (NFS) ability is highlighted in the so-called polymer decoration technique in which vapors of polyethylene condense and crystallize on a cold fold surface substrate to form edge-on lamellae that reveal the folds and loops orientations in different growth sectors. In bulk materials, the primary crystallization leaves confined and uncrystallized material between lamellae. NFS, based on epitaxy-type interactions, is expected to take place in these confined and supercooled melt fractions before “true” homogeneous nucleation sets in. The insights provided help elucidate the structural features of the interlamellar layers of crystalline polymers, which overcomes the limits of global, indirect investigation techniques (e.g., differential scanning calorimetry (DSC)) used in attempts to analyze their structure in situ. The interlamellar layer is known to be divided into a rigid amorphous fraction (RAF) located in contact with the fold surfaces and a mobile amorphous fraction (MAF) at its center. The nature of the RAFamorphous but rigid above its T g, or crystallineis still debated. The NFS provides a structural identity for the RAF that associates conformation disorder with stem orientation: the RAF is actually a “condis oriented” fraction. On heating, the small endotherm observed in DSC curves corresponds to its isotropization. The RAF is also a protonucleus for secondary crystallization and induces the growth of edge-on lamellae on top and in the interlamellar spaces of the primary crystals. As such, the RAF has also a layered lamellar structure. Polymer decoration, the “condis oriented” RAF, and the specific edge-on lamellar secondary crystallization are manifestations of the nucleation by the fold surfaces.

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Insertion‐Crystallization‐Induced Low‐Temperature Annealing Peaks in Melt‐Crystallized Poly(l‐Lactic Acid)

Androsch

Toda

Furushima

et al. 2021

Macro Chemistry & Physics

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Annealing of poly(l‐lactic acid) (PLLA) at temperatures lower than the temperature of primary melt‐crystallization leads to appearance of distinct low‐temperature annealing peaks in subsequently recorded calorimeter heating scans. Reason is continuation of crystallization by growth of crystals of lower stability as formed during primary crystallization. The assignment of low‐temperature annealing peaks to crystallization is based on a robust analysis of the decrease of the heat capacity of the semicrystalline structure slightly above the glass transition temperature and its correlation with the corresponding enthalpy of crystallization. Comparison of the form of annealing peaks with classical enthalpy‐recovery peaks obtained on devitrification of the glassy amorphous phase of semicrystalline PLLA supports the interpretation regarding the origin of annealing peaks.

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Glass transition and aging of the rigid amorphous fraction in polymorphic poly(butene-1)

Cited by 6 publications

References 63 publications

Unraveling the Influence of the Preexisting Molecular Order on the Crystallization of Semiconducting Semicrystalline Poly(9,9-di-n-octylfluorenyl-2,7-diyl (PFO)

Unraveling the Influence of the Preexisting Molecular Order on the Crystallization of Semiconducting Semicrystalline Poly(9,9-di-n-octylfluorenyl-2,7-diyl (PFO)

Fold Surfaces of Polymer Crystals Are Nucleation Sites: The Link between Polymer Decoration, Secondary Crystallization, and the Rigid Amorphous Fraction (RAF)

Insertion‐Crystallization‐Induced Low‐Temperature Annealing Peaks in Melt‐Crystallized Poly(l‐Lactic Acid)

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