SANS Evidence of Liquid–Liquid Phase Separation Leading to Inversion of Crystallization Rate of Broadly Distributed Random Ethylene Copolymers

Chen, Xuejian; Wígnall, G. D.; He, Lilin; López‐Barrón, Carlos R.; Alamo, Rufina G.

doi:10.1021/acs.macromol.7b00357

Cited by 17 publications

(21 citation statements)

References 49 publications

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“…Additionally, after complete melting of polymeric crystals, some memory of the crystalline ordered structure can still survive, and the crystallization of the polymer can be enhanced by melt memory effects. [6][7][8][9][10][11] Polybutene-1 is a polyolefin with excellent mechanical properties and complex polymorphic behavior that has attracted much interest from both industry and academia. 12,13 The tetragonal Form II with an 11/3 helix can be obtained by cooling the sample directly from the melt.…”

Section: Introductionmentioning

confidence: 99%

Promotion of Self-Nucleation with Latent Form I Nuclei in Polybutene-1 and Its Copolymer

et al. 2018

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The formation of Form I nuclei of polybutene-1 (PB-1) and its copolymer with polyethylene (PB1-ran-PE) has been studied by means of modified self-nucleation protocols. Even when the self-nucleation temperature was high enough and all Form II crystals melt, re-crystallization can be accelerated if the melt-crystallized sample was annealed at low temperatures (below 60 o C for PB-1 and 75 o C for PB1-ran-PE) for just 3 min. These results suggest the formation of latent Form I nuclei within Form II crystals. This hypothesis is consistent with the observed growth of a small amount of Form I crystals during heating, after previous annealing at temperature lower than 20 °C.In addition, a peculiar phenomenon was found in PB1-ran-PE, as both Form II and Form I′ can be induced by the presence of latent Form I nuclei, due to cross-nucleation and self-nucleation effects, respectively. The final ratio of the two kinds of crystal Forms is a result of the competition between the two nucleation rates, which strongly depend on crystallization temperature. In this work, we have shown that careful design of novel self-nucleation protocols can yield evidence of the early stages of Form II to Form I transition, even when the degree of transformed crystals is below the limit of detection of conventional techniques sensitive to crystalline order (DSC, WAXD, FTIR).

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Section: Introductionmentioning

confidence: 99%

Promotion of Self-Nucleation with Latent Form I Nuclei in Polybutene-1 and Its Copolymer

et al. 2018

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“…Comparing with the homopolymer PB‐1, which possesses a narrow Domain II , it is noticeable that self‐nuclei of P(B1‐ran‐E) can survive even above the equilibrium melting temperature of PB‐1 homopolymer (148°C), 46 alike other polyethylene copolymers 15,16,29 . In particular, based on the definition proposed by Müller et al, 7,17,26 Domain II could be divided into Domain IIa , if the heat flow signal reaches the baseline (indicating all crystals have melted), and Domain IIb , if the signal is still within the melting endotherm (indicating that a small crystal population or crystal fragments remain that can act as self‐seeds).…”

Section: Resultsmentioning

confidence: 99%

“…Alamo et al 15,16,29 observed an unexpected strong melt memory effect in polyethylene copolymers above the equilibrium melting temperature. They interpreted the mechanism behind this peculiar phenomenon as the formation of a complex topology of knots, loops, ties, and other entanglements within the inter‐crystalline regions, which are caused by the selection and dragging process of polymer chains when suitable ethylene sequences with low branch contents are packed into the lattice.…”

Section: Introductionmentioning

confidence: 97%

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Peculiar self‐nucleation behavior of a polybutene‐1/ethylene random copolymer

Wang

Dong

Cavallo

et al. 2021

Polymer Crystallization

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The self‐nucleation behavior of a polybutene‐1/ethylene random copolymer, P(B1‐ran‐E), which undergoes a complex crystal‐crystal transition behavior, has been studied in detail. Similar to PE random copolymers, this material shows a strong melt memory effect even above equilibrium melting point of PB‐1 homopolymer. Different polymorphic forms can be obtained when P(B1‐ran‐E) is cooled from different self‐nucleation domains. The trigonal form I′ could only be nucleated in the presence of remaining form I crystals via self‐seeding, while the melt memory in Domain IIa could only act as self‐nuclei for kinetically favored form II. Furthermore, observations from optical microscopy illustrated that melt memory is able to enhance nucleation density but it does not affect the spherulitic growth rate.

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“…For examples, Knauer et al labeled the chain ends of polyethersulfone (PESU), to locate the accurate position of chain ends in PESU thin film‐air interface . Chen et al investigated the mechanism of liquid–liquid phase separation in random ethylene 1‐hexene copolymer by adding deuterium to certain fractions . Deuterated polyethylene (PE) was proved to be the key in elucidating the shish‐kebab superstructures and chain alignment of PE under cold‐draw through small‐angle neutron scattering (SANS) .…”

Section: Introductionmentioning

confidence: 99%

Isotope Effects on the Crystallization Kinetics of Selectively Deuterated Poly(ε‐Caprolactone)

Chang

Arras

et al. 2019

J Polym Sci B Polym Phys

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Deuterium labeling of semi-crystalline polymers can dramatically affect their crystallization behaviors. However, the influence of different labeled positions in a partially deuterated polymer on its crystallization is still far from understood. Here, we synthesized a series of selectively deuterated poly(ε-caprolactones) (PCLs) through ring-opening polymerization of ε-caprolactone with controlled deuteration sites, including fully protiated (D0), fully deuterated (D10), tetra deuteration at the 3-and 7-caprolactone ring positions (D4) and hexa deuteration at the 4-, 5-, and 6-caprolactone ring positions (D6). All the PCLs showed a similar lamellar structure and parameters. Differential scanning calorimetry (DSC) analysis revealed that the equilibrium melting temperature T 0 m , melting temperature T m , crystallization temperature T c , and crystallization kinetics changed systemically with the deuterium content except for D4, which indicates that the presence of CD 2 moieties on either side of ester group in the polymer chain combined with isotopic inhomogeneity could influence the chain packing. The nonmonotonic trend of T m as a function of deuterium content could be attributed to the difference in a hydrogen-bond like intermolecular interaction between different PCLs. Partially deuterated PCLs (D4 and D6) showed an Avrami index near 2. After analyzing the parameters at the same supercooling temperature ΔT c , the existence of two crystallization regimes of PCLs were detected.

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SANS Evidence of Liquid–Liquid Phase Separation Leading to Inversion of Crystallization Rate of Broadly Distributed Random Ethylene Copolymers

Cited by 17 publications

References 49 publications

Promotion of Self-Nucleation with Latent Form I Nuclei in Polybutene-1 and Its Copolymer

Promotion of Self-Nucleation with Latent Form I Nuclei in Polybutene-1 and Its Copolymer

Peculiar self‐nucleation behavior of a polybutene‐1/ethylene random copolymer

Isotope Effects on the Crystallization Kinetics of Selectively Deuterated Poly(ε‐Caprolactone)

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