Stretching‐induced phase transition of the butene‐1/ethylene random copolymer: Orientation and kinetics

Wang, Wei; Shao, Chunguang; Zheng, Lirong; Wang, Bin; Pan, Li; Ma, Guiqiu; Li, Yuesheng; Wang, Yaming; Liu, Chuntai; Ma, Zhe

doi:10.1002/polb.24764

Cited by 33 publications

(40 citation statements)

References 52 publications

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“…However, Form I′, described as a defective Form I with lower melting temperature, can be formed through special crystallization procedures, such as solution crystallization, blending with iPP, or copolymerization with other monomers . Actually, quiescent aging at room temperature of Form II samples is generally used for generating trigonal Form I, where the molecular conformation of the chains is that of a 3/1 helix …”

Section: Introductionmentioning

confidence: 99%

Cross‐nucleation of polybutene‐1 Form II on Form I seeds with different morphology

Wang

Carmeli

et al. 2020

Polymer Crystallization

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Polybutene-1 (PB-1) trigonal Form I crystals with different morphologies, namely spherulitic, hedritic, and fibrous, were used as seeds to quantitatively study the cross-nucleation kinetics of the tetragonal Form II. Interestingly, a large difference in the cross-nucleation ability of the various Form I seeds was observed. The Form I fiber exhibits the fastest cross-nucleation, followed by the hedrite and eventually by the spherulite. The nucleation induction time was quantified from the evolution of the transmitted light intensity via polarized optical microscopy. The data were tested against different nucleation models, revealing that the rate-determining step for nucleation is the growth of the nucleus to attain the critical dimension, rather than the formation of the first crystalline layer in contact with the substrate. In addition, for spherulitic seeds, a meaningful dependence of cross-nucleation induction time on Form I lamellar thickness was found, with the kinetics being faster for higher original seed's crystallization temperatures. The results were interpreted assuming a free energy barrier for cross-nucleation which is a function of the mismatch between the daughter and the parent polymorphs' lamellar dimensions. This aspect, together with the calculated low values of interfacial free energy difference parameter for nucleation, suggests the possible existence of an epitaxial relationships between crossnucleating PB-1 Form II and Form I. K E Y W O R D Scross-nucleation, morphology, polybutene-1, polymorphism

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Section: Introductionmentioning

confidence: 99%

Cross‐nucleation of polybutene‐1 Form II on Form I seeds with different morphology

Wang

Carmeli

et al. 2020

Polymer Crystallization

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“…Of particular interest, also for its cross-nucleation behavior, is polybutene-1 (PB-1), which exhibits pronounced polymorphism that can be distinguished by the chain conformation and packing mode of segmental stems . Different helical conformations, that is, the 3/1, 11/3, and 4/1 helixes, can pack into trigonal (form I), tetragonal (form II), and orthorhombic (form III) unit cells. , Among them, the form I unit cell parameters are a = b = 17.5 Å, c (chain axis) = 6.477 Å, and γ = 120° (with space group P 3̅), while form II exhibits a tetragonal unit cell with the parameters a = b = 14.9 Å and c = 21.3 Å (with space group P 4̅ b2 ). − The kinetically favored, metastable form II can transform slowly and spontaneously into the stable form I at room temperature. , The transformation is greatly accelerated by the presence of mechanical stresses. , Thanks to the solid-state phase transition, seeds of form I into a PB-1 melt can be created, and form II was demonstrated to cross-nucleate on the surface of such seeds. , Our previous work has revealed that the cross-nucleation efficiency of form II on form I substrates increases with the thickening of form I lamellae, a fact that was interpreted as a possible hint of an epitaxial relationship between the two structures . Therefore, we now aim to further explore and resolve this issue by employing a nanofocused synchrotron X-ray beam on a cross-nucleated PB-1 sample.…”

Section: Introductionmentioning

confidence: 99%

“…39 Of particular interest, also for its cross-nucleation behavior, is polybutene-1 (PB-1), which exhibits pronounced polymorphism that can be distinguished by the chain conformation and packing mode of segmental stems. 40 Different helical conformations, that is, the 3/1, 11/3, and 4/1 helixes, can pack into trigonal (form I), tetragonal (form II), and orthorhombic (form III) unit cells. 41,42 Among them, the form I unit cell parameters are a = b = 17.5 Å, c (chain axis) = 6.477 Å, and γ = 120°(with space group P3̅ ), while form II exhibits a tetragonal unit cell with the parameters a = b = 14.9 Å and c = 21.3 Å (with space group P4̅ b2).…”

Section: ■ Introductionmentioning

confidence: 99%

“…46,47 The transformation is greatly accelerated by the presence of mechanical stresses. 40,48 Thanks to the solid-state phase transition, seeds of form I into a PB-1 melt can be created, and form II was demonstrated to cross-nucleate on the surface of such seeds. 32,33 Our previous work has revealed that the cross-nucleation efficiency of form II on form I substrates increases with the thickening of form I lamellae, a fact that was interpreted as a possible hint of an epitaxial relationship between the two structures.…”

Section: ■ Introductionmentioning

confidence: 99%

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Epitaxy in Polybutene-1 Form II-on-Form I Cross-Nucleation Revealed by Nanofocused X-ray Diffraction on Ad Hoc Morphology

Wang

Looijmans

et al. 2021

Macromolecules

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The existence of epitaxy in polybutene-1 form IIon-form I cross-nucleation was investigated by nanofocused synchrotron X-ray diffraction. To this aim, form I hedrites, which show a lamellar stacking with a uniform crystal lattice orientation, were adopted as the substrate. The form II crystals develop a spherulitic transcrystalline layer on the lateral surface of the form I substrate, due to cross-nucleation. Through mapping both the intensity and azimuthal orientation of characteristic planes of the two polymorphs, a clearly defined nucleation area between form II (daughter) and form I (parent) could be identified. Comparing the two-dimensional diffraction patterns in that area, a preferred mutual orientation of the two structure is revealed. In particular, the (200) II plane of form II and the (110) I plane of form I are reciprocally oriented at a fixed angle of ∼8.5°. This orientation results in almost parallel (110) planes between the two structures. It is calculated that the mismatch between interchain distances within the common ( 110) planes is about 4%, while that along the chain axes is less than 10%, both well below the accepted mismatch criterion for epitaxial crystallization. These results provide solid evidence for the existence of an epitaxial relationship in the cross-nucleation between polybutene-1 form II and form I. We note that the (110) contact plane between the two structures in cross-nucleation is the same as the one involved in the well-studied solid-state phase transformation from form II to form I. Moreover, the X-ray nanofocus approach and the proposed data analysis could be effectively applied to other cross-nucleating systems to shed light on the role of epitaxy in this peculiar phenomenon of nucleation between polymorphs.

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“…In addition to the physical means to tune the rate of phase transition [1,21,22,23,24,25,26,27], the chemical regulation of macromolecular structure is another efficient method [28,29,30,31,32]. The molecular structure can be designed by varying molecular weight, as well as regularity, or incorporating the extra structural co-units.…”

Section: Introductionmentioning

confidence: 99%

Thermal Analysis of Crystallization and Phase Transition in Novel Polyethylene Glycol Grafted Butene-1 Copolymers

Lou

et al. 2019

Polymers

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Copolymerization is an effective strategy to regulate the molecular structure and tune crystalline structures. In this work, novel butene-1 copolymers with different polyethylene glycol (PEG) grafts (number-average molecular weight Mn = 750, 2000, and 4000 g/mol) were synthesized, for the first time introducing long-chain grafts to the polybutene-1 main chain. For these PEG-grafted copolymers, crystallization, melting, and phase transition behaviors were explored using differential scanning calorimetry. With respect to the linear homopolymer, the incorporation of a trimethylsilyl group decreases the cooling crystallization temperature (Tc), whereas the presence of the long PEG grafts unexpectedly elevates Tc. For isothermal crystallization, a critical temperature was found at 70 °C, below which all polyethylene glycol-grafted butene-1 (PB-PEG) copolymers have faster crystallization kinetics than polybutene-1 (PB). The subsequent melting process shows that for the identical crystallization temperature, generated PB-PEG crystallites always have lower melting temperatures than that of PB. Moreover, the II-I phase transition behavior of copolymers is also dependent on the length of PEG grafts. When form II, obtained from isothermal crystallization at 60 °C, was annealed at 25 °C, PB-PEG-750, with the shortest PEG grafts of Mn = 750 g/mol, could have the faster transition rate than PB. However, PB-PEG-750 exhibits a negative correlation between transition rate and crystallization temperature. Differently, in PB-PEG copolymers with PEG grafts Mn = 2000 and 4000 g/mol, transition rates rise with elevating crystallization temperature, which is similar with homopolymer PB. Therefore, the grafting of the PEG side chain provides the available method to tune phase transition without sacrificing crystallization capability in butene-1 copolymers.

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Stretching‐induced phase transition of the butene‐1/ethylene random copolymer: Orientation and kinetics

Cited by 33 publications

References 52 publications

Cross‐nucleation of polybutene‐1 Form II on Form I seeds with different morphology

Cross‐nucleation of polybutene‐1 Form II on Form I seeds with different morphology

Epitaxy in Polybutene-1 Form II-on-Form I Cross-Nucleation Revealed by Nanofocused X-ray Diffraction on Ad Hoc Morphology

Thermal Analysis of Crystallization and Phase Transition in Novel Polyethylene Glycol Grafted Butene-1 Copolymers

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