Crystallization of tethered polyethylene in confined geometries

Weimann, Peter A.; Hajduk, Damian A.; Chu, Crystal K.; Chaffin, Kimberly A.; Brodil, J. C.; Bates, Frank S.

doi:10.1002/(sici)1099-0488(19990815)37:16<2053::aid-polb9>3.3.co;2-c

Cited by 74 publications

(127 citation statements)

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“…That the crystallization of the PEG block of the PLLA15000–PEG5000 diblock copolymer needs a larger degree of supercooling (crystallization temperature < −15 °C) is a very interesting and important experimental phenomenon. A similar experimental result has also been published in articles about other systems 29–35. It results from the fact that the nucleation mechanism of the PEG block is different from that of the other two diblock copolymers in the confined microdomain structure.…”

Section: Resultssupporting

confidence: 76%

Nonisothermal crystallization behavior of the poly(ethylene glycol) block in poly(L‐lactide)–poly(ethylene glycol) diblock copolymers: Effect of the poly(L‐lactide) block length

Yang

Zhao

Cui

et al. 2006

J Polym Sci B Polym Phys

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The confined crystallization behavior, melting behavior, and nonisothermal crystallization kinetics of the poly(ethylene glycol) block (PEG) in poly(L-lactide)poly(ethylene glycol) (PLLA-PEG) diblock copolymers were investigated with wideangle X-ray diffraction and differential scanning calorimetry. The analysis showed that the nonisothermal crystallization behavior changed from fitting the Ozawa equation and the Avrami equation modified by Jeziorny to deviating from them with the molecular weight of the poly(L-lactide) (PLLA) block increasing. This resulted from the gradual strengthening of the confined effect, which was imposed by the crystallization of the PLLA block. The nucleation mechanism of the PEG block of PLLA15000-PEG5000 at a larger degree of supercooling was different from that of PLLA2500-PEG5000, PLLA5000-PEG5000, and PEG5000 (the numbers after PEG and PLLA denote the molecular weights of the PEG and PLLA blocks, respectively). They were homogeneous nucleation and heterogeneous nucleation, respectively. The PLLA block bonded chemically with the PEG block and increased the crystallization activation energy, but it provided nucleating sites for the crystallization of the PEG block, and the crystallization rate rose when it was heterogeneous nucleation. The number of melting peaks was three and one for the PEG homopolymer and the PEG block of the diblock copolymers, respectively. V V C 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: [3215][3216][3217][3218][3219][3220][3221][3222][3223][3224][3225][3226] 2006

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Section: Resultssupporting

confidence: 76%

Nonisothermal crystallization behavior of the poly(ethylene glycol) block in poly(L‐lactide)–poly(ethylene glycol) diblock copolymers: Effect of the poly(L‐lactide) block length

Yang

Zhao

Cui

et al. 2006

J Polym Sci B Polym Phys

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“…Crystalline behavior of a polymer can be altered through chemical modification. Crosslinking of polymer chains results in reduction in T m , crystallization rates, and the observed degree of crystallinity 32. Special investigations were directed to show the dependency of the peroxide content on the crystalline structure.…”

Section: Resultsmentioning

confidence: 99%

Thermal and wide angle X‐ray analysis of chemically and radiation‐crosslinked low and high density polyethylenes

Khonakdar

Jafari

Taheri

et al. 2006

J of Applied Polymer Sci

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Low and high density polyethylenes (PE) were crosslinked by two methods, namely, chemically by use of different amounts of tert-butyl cumyl peroxide (BCUP) and by irradiation with different doses of electron beam. A comparison between the effects of these two types of crosslinking on crystalline structure, crystallinity, crystallization, and melting behaviors of PE was made by wide angle X-ray diffraction and DSC techniques. Analysis of the DSC first heating cycle revealed that the chemically induced crosslinking, which took place at melt state, hindered the crystallization process and decreased the degree of crystallinity, as well as the size of crystals. Although the radiationinduced crosslinking, which took place at solid state, had no significant influence on crystalline region, rather, it only increased the melting temperature to some extent. However, during DSC cooling cycle, the crystallization temperature showed a prominent decrease with increasing irradiation dose. The wide angle X-ray scattering analysis supported these findings. The crystallinity and crystallite size of chemically crosslinked PE decreased with increasing peroxide content, whereas the irradiation-crosslinked PE did not show any change in these parameters. As compared with HDPE, LDPE was more prone to crosslinking (more gel content) owing to the presence of tertiary carbon atoms and branching as well as owing to its being more amorphous in nature. HDPE, with its higher crystalline content, showed relatively less tendency toward crosslinking especially by way of irradiation at solid state.

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“…Hamley et al5 studied the crystallization kinetics of CE diblock copolymers and found that the crystallinity of the E block was limited by the amount of branching, independent of the quench temperature. Weimann and coworkers investigated the effect of the architecture (CE versus CEC), molecular weight, and composition on the percent crystallinity ( X c ) and melting temperature ( T m ); in this work “E” refers to a random copolymer containing 7% E E and 93% E repeat units, i.e., x = 0.07 6. The percent crystallinity was found to be independent of the block copolymer morphology for both the CE and CEC architectures, but was dependent on the molecular weight of the E block in CEC but not in CE.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic characteristics of poly(cyclohexylethylene‐b‐ethylene‐co‐ethylethylene) block copolymers

Mansour

Johnson

Lodge

et al. 2010

J Polym Sci B Polym Phys

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A series of poly(cyclohexylethylene-b-ethylene-coethylethylene) (C-E/E E ) diblock copolymers containing approximately 50% by volume glassy C blocks and varying fraction (x) of E E repeat units, 0.07x 0.90, was synthesized by anionic polymerization and catalytic hydrogenation. The effects of ethyl branch content on the melt state segment-segment (v) interaction parameter and soft (E/E E ) block crystallinity were studied. The percent crystallinity ranged from approximately 30% at x ¼ 0.07 to 0% at about x ! 0.30, while the melting temperature changed from 101 C at x ¼ 0.07 to 44 C at x ¼ 0.28. Dynamic mechanical spectroscopy was employed to determine the order-disorder transition (ODT) temperatures, from which v was calculated assuming the mean-field prediction (vN n ) ODT ¼ 10.5. Previously published results for the temperature dependent binary interaction parameters for C-E (x ¼ 0.07), C-E E (x ¼ 0.90), and E-E E (x ¼ 0.07 and x ¼ 0.90) fail to account for the quantitative x dependence of v, based on a simple binary interaction model.

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Crystallization of tethered polyethylene in confined geometries

Cited by 74 publications

References 0 publications

Nonisothermal crystallization behavior of the poly(ethylene glycol) block in poly(L‐lactide)–poly(ethylene glycol) diblock copolymers: Effect of the poly(L‐lactide) block length

Nonisothermal crystallization behavior of the poly(ethylene glycol) block in poly(L‐lactide)–poly(ethylene glycol) diblock copolymers: Effect of the poly(L‐lactide) block length

Thermal and wide angle X‐ray analysis of chemically and radiation‐crosslinked low and high density polyethylenes

Thermodynamic characteristics of poly(cyclohexylethylene‐b‐ethylene‐co‐ethylethylene) block copolymers

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