Journal: Journal of Polymer Science

Abbreviation

J. Polym. Sci.

Publisher

Wiley

Journal Volumes

ISSN

2642-4169
2642-4150

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2020 - 202411
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Publications 1 - 10 of 11
  • Gas-phase polymerization of ultra-high molecular weight polyethylene with decreased entanglement density
    Item type: Journal Article
    Lopes do Rosario, Roberta; Christakopoulos, Fotios; Tervoort, Theo A.; et al. (2023)
    Journal of Polymer Science
    It is well known that ultra-high molecular weight polyethylene (UHMWPE) is a polymer with long chains and very high molecular weight that poses difficulties in terms of processability due to the presence of chain entanglements. In many cases is thus necessary to treat the material in different ways after the polymerization to minimize the amount of entanglements and improve the processability. Based on observations that the use of inert condensing agents (ICA) had a noticeable impact on molecular weight and crystallinity, it was decided to develop a gas-phase polymerization process with addition of ICA for UHMWPE with a high fraction of disentangled chains. For the optimization of this process, the comparison with slurry is important for the understanding the improvement. Thus, a clear difference between slurry and gas phase is observed in terms of crystallinity and the lamellar thickness of the crystals, molecular weight and entanglements. Characterization techniques are developed to measure the properties of the reactor powder and understand the impact of the alkanes in situ. Using solid-state drawability, the entanglement degree of the reactor powder is analyzed. From the small-angle x-ray scattering and wide-angle x-ray scattering techniques, it is possible to find a correlation of entanglements and lamellar thickness. Moreover, crystallization kinetics measurements of the polymer in presence of ICA constitutes a powerful method to explain the phenomena of entanglement and crystal formation.
  • Depolymerization of poly(α‐methyl styrene) with ball‐mill grinding
    Item type: Journal Article
    Jung, Eunsong; Yim, Daniel; Kim, Hyungjun; et al. (2023)
    Journal of Polymer Science
    The development of mild methods to depolymerize polymers has become increasingly important in our current Age of Plastics, and ball-mill grinding (BMG) is emerging as a promising candidate. In this report, we demonstrate that subjecting poly(α-methyl styrene) (PMS) to BMG leads to high extents of depolymerization (up to 64 mol% of α-methyl styrene was produced) with minimal side products after only minutes of grinding. Constrained geometries simulate external force (CoGEF) simulations and radical trapping experiments supported that the depolymerization was initiated by mechanochemical chain scission. Depolymerization proceeded despite bulk temperatures remaining far below that of the ceiling temperature of PMS. Control experiments suggested that the extent of depolymerization was equilibrium controlled. Polystyrene and poly(methyl methacrylate) also underwent depolymerization, although to a much lesser degree (up to 4% monomer produced), presumably due to their much higher ceiling temperatures. This work provides an entry point for further development of BMG as a tool for the depolymerization of vinyl polymers under mild conditions.
  • Maltodextrin as stabilizer for emulsion polymerization: Adsorption and grafting behavior
    Item type: Journal Article
    Ferrari, Raffaele; Storti, Giuseppe; Morbidelli, Massimo (2020)
    Journal of Polymer Science
  • Influence of solid‐state biaxial orientation on the adhesion between poly(ethylene terephthalate)/tie layer/isotactic polypropylene multilayer films
    Item type: Journal Article
    Ghazaryan, Gagik; Hausmann, Karlheinz; Tervoort, Theo A. (2020)
    Journal of Polymer Science
  • Understanding dispersity control in photo-atom transfer radical polymerization: Effect of degree of polymerization and kinetic evaluation
    Item type: Journal Article
    Rolland, Manon; Lohmann, Victoria; Whitfield, Richard; et al. (2021)
    Journal of Polymer Science
    In photo-atom transfer radical polymerization (ATRP), dispersity can be efficiently controlled by varying the deactivator concentration. In this work, we provide mechanistic insight into dispersity-controlled photo-ATRP by conducting detailed kinetics under a range of conditions. For the lower dispersity polymers, a conventional first-order kinetic profile was observed accompanied by a linear evolution of number average molecular weight (Mn) with conversion while the reactions reached moderate to high conversions (between 66% and 93%). Whereas, when polymers of high dispersity were targeted, the Mn remained relatively constant throughout the polymerization and the reactions ceased at less than 50% of conversion. In particular, for Ð = 1.84, a significant deviation between theoretical and experimental molecular weights was evident. This deviation was unambiguously attributed to slow initiation as indicated by 1H NMR, where significant percentages of unreacted initiator were observed. Importantly, the addition of ligand at the polymerization plateau re-initiated the polymerization and led to the complete consumption of the unreacted initiator, thus enabling the synthesis of one-pot diblock copolymers. We subsequently evaluated the effect of the degree of polymerization (DP) on the obtained dispersity when a constant catalyst ratio was maintained. Based on the interpolation of those experiments results, we could predict experimental conditions for any desirable DPs and dispersities.
  • Enhancing photothermal depolymerization with metalloporphyrin catalyst
    Item type: Journal Article
    Ng, Gervase; Prescott, Stuart W.; Postma, Almar; et al. (2024)
    Journal of Polymer Science
    The ability to revert polymers to their original monomers represents a crucial chemical recycling technique, promoting sustainability and offering the chance to convert used materials into valuable products. In recent years, numerous studies have explored the use of polymers synthesized via reversible deactivation radical polymerization (RDRP) techniques to facilitate efficient depolymerization reactions. Herein, we report the use of a photocatalyst, zinc tetraphenylporphyrin (ZnTPP), along with light irradiation to accelerate depolymerization of polymers prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization. We explore various parameters affecting depolymerization efficiency, including solvents, reaction temperature (80, 100, and 120°C), the presence of photocatalysts (ZnTPP and Eosin Y), and the type of RAFT end-groups, namely trithiocarbonate, dithiobenzoate, and 1H-pyrazole-1-carbodithioate. For instance, when PMMA was diluted to 25 mM in 1,4-dioxane and heated to 120°C under green light irradiation in the presence of ZnTPP (200 ppm), rapid depolymerization exceeding 70% occurred within 1 h. Without ZnTPP, under similar conditions, the reaction required over 8 h to achieve a slightly lower yield. Furthermore, this method confers moderate oxygen tolerance to the system, enabling depolymerization to proceed without the need of deoxygenation, albeit at a lower rate and consequently lesser monomer recovery (31%).
  • Oxygen-enhanced superoxido copper-catalyzed ATRP accelerated by light
    Item type: Journal Article
    Della Casa, Sina; Parkatzidis, Kostas; Truong, Nghia P.; et al. (2023)
    Journal of Polymer Science
    Oxygen-enhanced atom transfer radical polymerization (ATRP) via the formation of a superoxido copper complex, has recently emerged as a powerful tool for the synthesis of well-defined polymers. However, relatively long reaction times (>8 h) were required to reach high monomer conversions. Herein, we explore the influence of light in this new polymerization procedure. Under UV irradiation, a significant enhancement over the polymerization rate was observed resulting in near-quantitative monomer consumption (>90%) within 2 h and narrow molar mass distributions (D = 1.07). The rate acceleration was attributed to the fast reduction of the superoxido copper complex to Cu(I)Br under UV irradiation, as confirmed via detailed UV-Vis kinetic experiments. In addition, the induction period was completely eliminated, which is in stark contrast to conventional photo-ATRP (utilizing Cu(II)Br), thus further highlighting the superiority of the presented system. The synergy of the superoxido complex and UV irradiation enabled the synthesis of low-dispersity homopolymers with molecular weights ranging from 6000 to 300,000. The high end-group fidelity of the system was further demonstrated via successful in -situ chain-extensions.
  • Influence of electron‐beam irradiation on plasticity‐controlled and crack‐growth‐controlled failure in high‐density polyethylene
    Item type: Journal Article
    Cerpentier, Robin R.J.; Boerakker, Mark J.; Tervoort, Theo A.; et al. (2022)
    Journal of Polymer Science
    In the present study, the influence of electron-beam irradiation on plasticity-controlled and crack-growth-controlled failure in high-density polyethylene (HDPE) is investigated and the effect of both molecular weight distribution (MWD) and short chain branching (SCB) content are taken into account. Size exclusion chromatography (SEC) is used to study the evolution of the MWD of the sol fraction as a function of irradiation dose. Here, it is seen that chains shorter than the percolation threshold (5 kDa) are largely unaffected by electron beam radiation, while the fraction of longest chains (M > 300 kDa) is nearly entirely incorporated into the cross-linked network. Both yield stress and Young's modulus increased with irradiation dose, where the magnitude of the increase appears to be connected to the gel fraction. The (fatigue) crack growth kinetics of the grades changed relatively little with irradiation dose, which is unexpected. Furthermore, convergence of the crack growth kinetics parameter to a narrow range of values could be observed for the investigated grades at relatively high gel fractions. This would imply that the crack growth kinetics become increasingly independent of the MWD upon irradiation cross-linking, which could be attributed to a shift in the underlying crack growth mechanism from chain slip to chain scission.
  • Helical bias in supramolecular polymers accounts for different stabilities of kinetically trapped states
    Item type: Journal Article
    Ślęczkowski, Marcin L.; Mabesoone, Mathijs F.J.; Preuss, Marco D.; et al. (2022)
    Journal of Polymer Science
    The idea to synthesize and self-assemble nano-graphenes with structural precision into supramolecular polymers is just one of Klaus Müllen's many pioneering contributions to the chemical sciences. To honor his impact in the field of polymer science, we here describe a study that combines experimental and computational methods in studying the stability of kinetically trapped states of supramolecular polymers. We show that the introduction of stereocenters in the sidechains allow helical supramolecular polymers based on chiral triphenylene-2,6,10-tricarboxamide monomers to escape a kinetic trap more efficiently than polymers based on their achiral analogs. Partial depolymerization of the kinetically trapped state by increasing the temperature followed by polymerization by lowering the temperature shows that monomers either polymerize on existing stacks or self-nucleate to form the thermodynamically more stable state. Chiral monomers prefer the latter more than achiral monomers.
  • Synthesis of WellDefined Poly(norbornene) Containing Carbon Nanodots by Controlled ROMP
    Item type: Journal Article
    Bang, Ki-Taek; Choi, Tae Lim (2020)
    Journal of Polymer Science
    The authors reported the synthesis of welldefined poly(norbornene) having hexaperihexabenzocoronene (HBC) moiety by ROMP. After optimization, the 3rd generation Grubbs catalyst enabled precise control of the molecular weight of the polymer with a narrow dispersity. This controlled polymerization the authors to begin the preparation of the block copolymer containing HBC for the first time.
Publications 1 - 10 of 11