The challenges of controlling polymer synthesis at the molecular and macromolecular level

Hakobyan, Karen; Xu, Jiangtao; Müllner, Markus

doi:10.1039/d1py01581h

Cited by 10 publications

(5 citation statements)

References 245 publications

(369 reference statements)

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“…The structure of polymers can be tailored in many different ways, and there are many ways of controlling the architecture even using classical radical polymerization techniques . Branching is one type of polymer architecture, and this can take several forms including hyperbranching or dendrimeric. − Branched polymers have been investigated for several oilfield production flow line applications.…”

Section: Introductionmentioning

confidence: 99%

Comparing the Kinetic Hydrate Inhibition Performance of Linear versus Branched Polymers

Kelland,

Dirdal,

Knutsen

2024

ACS Omega

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Kinetic hydrate inhibitors (KHIs) are a chemical method of preventing gas hydrate plugging of oil and gas production flow lines. The main ingredient in a KHI formulation is one or more water-soluble amphiphilic polymers. Poly(N-vinyl caprolactam) (PVCap) is an unbranched polymer and a well-known industrial KHI, often used as a yardstick to compare the performance of new polymers. The effect of branching PVCap on KHI performance has been investigated by polymerizing the VCap monomer in the presence of varying amounts of trimethylolpropane triacrylate, pentaerythritol tetraacrylate, or bis-pentaerythritol hexaacrylate crosslinkers to give PVCap polymers with 3, 4, and 6 branches, respectively. If the ratio of cross-linker to VCap was too high (6:1 to 8:1), gelling and/or poor water solubility was observed, giving short polymer chains and poor KHI efficacy. For higher ratios (30:1 to 60:1), it was found that the concentration of the polymer needed to give total inhibition of structure II tetrahydrofuran hydrate crystal growth could be lowered by using tribranched rather than linear PVCap. Slow constant cooling (1 °C/h) gas hydrate experiments with a synthetic natural gas in steel rocking cells at 76 bar were also carried out. A small improvement in KHI performance was observed for one of the branched PVCaps compared with a linear PVCap. Branched and linear poly(Nisopropylmethacrylamide) (PNIPMAm) polymers were also investigated in the gas hydrate system, but there was no benefit observed when branching this polymer class.

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Section: Introductionmentioning

confidence: 99%

Comparing the Kinetic Hydrate Inhibition Performance of Linear versus Branched Polymers

Kelland,

Dirdal,

Knutsen

2024

ACS Omega

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“…The preparation of large-area sequence-controlled polymer junctions remains two intractable issues including their sequence-controlled synthesis and unidirectional manipulation. It is well known that well-organized polymers seem unattainable on both nanoscopic and macroscopic scales (13,14) because polymer synthesis is an inherently divergent process yielding statistical and isotropic materials. The resulting disordered microstructures with many degrees of molecular conformations are inefficient for unidirectional charge hopping (15)(16)(17), and the tiny change of processing condition may affect the charge transport with large inconsistency over an order of magnitude even for the same molecule (18).…”

Section: Introductionmentioning

confidence: 99%

Composition and sequence-controlled conductance of crystalline unimolecular monolayers

Wang,

Zhao,

et al. 2023

Sci. Adv.

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Understanding how the charge travels through sequence-controlled molecules has been a formidable challenge because of simultaneous requirements in well-controlled synthesis and well-manipulated orientation. Here, we report electrically driven simultaneous synthesis and crystallization as a general strategy to study the conductance of composition and sequence-controlled unioligomer and unipolymer monolayers. The structural disorder of molecules and conductance variations on random positions can be extremely minimized, by uniform synthesis of monolayers unidirectionally sandwiched between electrodes, as an important prerequisite for the reproducible measurement on the micrometer scale. These monolayers show tunable current density and on/off ratios in four orders of magnitude with controlled multistate and massive negative differential resistance (NDR) effects. The conductance of monolayer mainly depends on the metal species in homo-metal monolayers, while the sequence becomes a matter in hetero-metal monolayers. Our work demonstrates a promising way to release an ultra-rich variety of electrical parameters and optimize the functions and performances of multilevel resistive devices.

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“…In contrast, iROP offered the possibility to generate more polymer chains from one active metal center, thus significantly reduced the catalyst loading. Therefore, iROP received considerable attention from academy and industry. − To establish a successful iROP, the transfer reaction between active species and CTAs must be rapid, reversible, and quantitative.…”

Section: Introductionmentioning

confidence: 99%

Controllable Synthesis of Heterofunctionalized Polyethers via Intramolecular Phosphonium Bisborane Lewis Pair-Catalyzed Immortal Ring-Opening Polymerization

et al. 2023

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A metal-free phosphonium bisborane Lewis pair (PBB-Br) was demonstrated to realize the immortal ring-opening polymerization (iROP) of propylene oxide (PO) under mild conditions with alcohols as chain-transfer agents (CTAs). Narrow dispersed poly(propylene oxides) (PPOs) with controllable molecular weights predicted from the [PO]0/([PBB-Br]0 + [CTAs]0) molar ratio were obtained in quantitative conversion. These findings indicated the iROP feature of PBB-Br-catalyzed PO polymerization. The rapid, reversible, and quantitative chain transfer assured the iROP characteristic for an intramolecular Lewis pair catalyst PBB-Br, so various well-defined heterofunctionalized PPOs were easily produced. All the α,ω-difunctionalized PPOs were carefully characterized. Density functional theory (DFT) calculations reveal that the chain transfer to the CTA process is almost barrierless (0.8 kcal mol–1) and thermodynamically favorable as compared to chain propagation. Moreover, PPO-based block copolyethers were easily obtained in one-pot using epoxide mixtures. This research demonstrated that the delicately designed intramolecular synergistic Lewis pair offered a powerful and controllable method to prepare various heterofunctionalized PPO samples with high values.

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The challenges of controlling polymer synthesis at the molecular and macromolecular level

Abstract: In this Perspective, we outline advances and challenges in controlling the structure of polymers at various size regimes in the context of structural features such as molecular weight distribution, end groups, architecture, composition and sequence.

Cited by 10 publications

References 245 publications

Comparing the Kinetic Hydrate Inhibition Performance of Linear versus Branched Polymers

Comparing the Kinetic Hydrate Inhibition Performance of Linear versus Branched Polymers

Composition and sequence-controlled conductance of crystalline unimolecular monolayers

Controllable Synthesis of Heterofunctionalized Polyethers via Intramolecular Phosphonium Bisborane Lewis Pair-Catalyzed Immortal Ring-Opening Polymerization

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