Kinetic Control of Chlorine Packing in Crystals of a Precisely Substituted Polyethylene. Toward Advanced Polyolefin Materials

Kaner, Papatya; Ruiz-Orta, Carolina; Boz, Emine; Wagener, Kenneth B.; Tasaki, Masafumi; Tashiro, Kohji; Alamo, Rufina G.

doi:10.1021/ma401541r

Cited by 39 publications

(90 citation statements)

References 40 publications

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“…Above 2800 cm −1 , two intense absorbances are observed at ∼2923 and 2850 cm −1 , which have been attributed to the alkyl C−H stretching modes of 1-methylimidazolium cations. 35,36 The imidazolium cation can further be identified by spectral features in the 1600−700 cm −1 region. The bands at ∼1570 and 1460 cm −1 are indicative of imidazole ring stretching, the peak at 1165 cm −1 has been assigned to imidazole H−C−C and H−C−N bending, and the broad band centered near 750 cm −1 is attributed to the out-ofplane C−H bending mode of the imidazole ring.…”

Section: Resultsmentioning

confidence: 99%

Dynamics of Precise Ethylene Ionomers Containing Ionic Liquid Functionality

Choi

Middleton²,

Soccio

et al. 2015

Macromolecules

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This paper presents the first findings on the molecular dynamics of the remarkable new class of linear and precisely functionalized ethylene copolymers. Specifically, we utilize broadband dielectric relaxation spectroscopy to investigate the molecular dynamics of linear polyethylene (PE)-based ionomers containing 1-methylimidazolium bromide (ImBr) pendants on exactly every 9th, 15th, or 21st carbon atom, along with one pseudorandom analogue. We also employed FTIR spectroscopy to provide insight into local ionic interactions and the nature of the ordering of the ethylene spacers between pendants. Prior X-ray scattering experiments revealed that the polar ionic groups in these ionomers self-assemble into microphase-separated aggregates dispersed throughout the nonpolar PE matrix. We focus primarily on the dynamics of the segmental relaxations, which are significantly slowed down compared to linear PE due to ion aggregation. Relaxation times depend on composition, the presence of crystallinity, and microphase-separated morphologies. Segmental relaxation strengths are much lower than predicted by the Onsager theory for mobile isolated dipoles but much higher than linear PE, demonstrating that at least some ImBr pendants participate in the segmental process. Analysis of the relaxation strengths using the Kirkwood g correlation factor demonstrates that ca. 10−40% of the ImBr ion dipoles (depending on copolymer composition and temperature) participate in the segmental motions of the precise ionomers under study, with the remainder immobilized or having net antiparallel arrangements in ion aggregates.

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Section: Resultsmentioning

confidence: 99%

Dynamics of Precise Ethylene Ionomers Containing Ionic Liquid Functionality

Choi

Middleton²,

Soccio

et al. 2015

Macromolecules

Self Cite

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“…Precision polymers are a subset of these materials that incorporate branches at perfectly spaced periodicity along a polyethylene chain . The regiospecific branching of these systems leads to well‐defined properties for specialty applications . Interestingly, precision ES copolymers have been scarcely reported.…”

Section: Introductionmentioning

confidence: 99%

A Precision Ethylene‐Styrene Copolymer with High Styrene Content from Ring‐Opening Metathesis Polymerization of 4‐Phenylcyclopentene

Neary

Kennemur

2016

Macromol. Rapid Commun.

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Ring-opening metathesis polymerization of 4-phenylcyclopentene is investigated for the first time under various conditions. Thermodynamic analysis reveals a polymerization enthalpy and entropy sufficient for high molar mass and conversions at lower temperatures. In one example, neat polymerization using Hoveyda-Grubbs second generation catalyst at -15 °C yields 81% conversion to poly(4-phenylcyclopentene) (P4PCP) with a number average molar mass of 151 kg mol(-1) and dispersity of 1.77. Quantitative homogeneous hydrogenation of P4PCP results in a precision ethylene-styrene copolymer (H2 -P4PCP) with a phenyl branch at every fifth carbon along the backbone. This equates to a perfectly alternating trimethylene-styrene sequence with 71.2% w/w styrene content that is inaccessible through molecular catalyst copolymerization strategies. Differential scanning calorimetry confirms P4PCP and H2 -P4PCP are amorphous materials with similar glass transition temperatures (Tg ) of 17 ± 2 °C. Both materials present well-defined styrenic analogs for application in specialty materials or composites where lower softening temperatures may be desired.

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“…Alkanes are modeled with two different united-atom (UA) force fields: PYS [14][15][16] and OPLS [17,18]. These force fields have been widely used to investigate the structure, interfacial properties and phase transitions of alkanes [4,12,[19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]. Water is modeled with the monatomic water model, mW [38], which has been extensively used to study the structure, thermodynamics, interfacial properties, and phase transitions of water .…”

Section: Methodsmentioning

confidence: 99%

Strength of Alkane–Fluid Attraction Determines the Interfacial Orientation of Liquid Alkanes and Their Crystallization through Heterogeneous or Homogeneous Mechanisms

Qiu

Molinero

2017

Crystals

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Abstract:Alkanes are important building blocks of organics, polymers and biomolecules. The conditions that lead to ordering of alkanes at interfaces, and whether interfacial ordering of the molecules leads to heterogeneous crystal nucleation of alkanes or surface freezing, have not yet been elucidated. Here we use molecular simulations with the united-atom OPLS and PYS alkane models and the mW water model to determine what properties of the surface control the interfacial orientation of alkane molecules, and under which conditions interfacial ordering results in homogeneous or heterogeneous nucleation of alkane crystals, or surface freezing above the melting point. We find that liquid alkanes present a preference towards being perpendicular to the alkane-vapor interface and more parallel to the alkane-water interface. The orientational order in the liquid is short-ranged, decaying over~1 nm of the surface, and can be reversed by tuning the strength of the attractions between alkane and the molecules in the other fluid. We show that the strength of the alkane-fluid interaction also controls the mechanism of crystallization and the face of the alkane crystal exposed to the fluid: fluids that interact weakly with alkanes promote heterogeneous crystallization and result in crystals in which the alkane molecules orient perpendicular to the interface, while crystallization of alkanes in the presence of fluids, such as water, that interact more strongly with alkanes is homogeneous and results in crystals with the molecules oriented parallel to the interface. We conclude that the orientation of the alkanes at the crystal interfaces mirrors that in the liquid, albeit more pronounced and long-ranged. We show that the sign of the binding free energy of the alkane crystal to the surface, ∆G bind , determines whether the crystal nucleation is homogeneous (∆G bind ≥ 0) or heterogeneous (∆G bind < 0). Our analysis indicates that water does not promote heterogeneous crystallization of the alkanes because water stabilizes more the liquid than the crystal phase of the alkane, resulting in ∆G bind > 0. While ∆G bind < 0 suffices to produce heterogeneous nucleation, the condition for surface freezing is more stringent, ∆G bind < −2 γ xl , where γ xl is the surface tension of the liquid-crystal interface of alkanes. Surface freezing of alkanes is favored by their small value of γ xl . Our findings are of relevance to understanding surface freezing in alkanes and to develop strategies for controlling the assembly of chain-like molecules at fluid interfaces.

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Kinetic Control of Chlorine Packing in Crystals of a Precisely Substituted Polyethylene. Toward Advanced Polyolefin Materials

Cited by 39 publications

References 40 publications

Dynamics of Precise Ethylene Ionomers Containing Ionic Liquid Functionality

Dynamics of Precise Ethylene Ionomers Containing Ionic Liquid Functionality

A Precision Ethylene‐Styrene Copolymer with High Styrene Content from Ring‐Opening Metathesis Polymerization of 4‐Phenylcyclopentene

Strength of Alkane–Fluid Attraction Determines the Interfacial Orientation of Liquid Alkanes and Their Crystallization through Heterogeneous or Homogeneous Mechanisms

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