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Gerakinis DP, Anogiannakis SD, Theodorou DN. Equilibration of linear polyethylene melts with pre-defined molecular weight distributions employing united atom Monte Carlo simulations. J Chem Phys 2024; 161:044901. [PMID: 39037144 DOI: 10.1063/5.0219728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2024] [Accepted: 07/08/2024] [Indexed: 07/23/2024] Open
Abstract
Possessing control over the molecular size (molecular weight/chain length/degree of polymerization) distribution of a polymeric material is extremely important in applications. This is manifested de facto by the extensive contemporary scientific literature on processes for controlling this distribution experimentally. Yet, the literature on computational techniques for achieving prescribed molecular size distributions in simulations and exploring their impact on properties is much less abundant than its experimental/technical counterpart. Here, we develop-on the basis of united atom melt simulations employing connectivity-altering Monte Carlo moves-a new Metropolis selection criterion that drives the multichain system to a prescribed but otherwise arbitrary distribution of molecular sizes. The new formulation is a generalization of that originally proposed [P. V. K. Pant and D. N. Theodorou, Macromolecules 28, 7224 (1995)], but simpler and more computationally efficient. It requires knowledge solely of the target distribution, which need not be normalized. We have implemented the new formulation on long-chain linear polyethylene melts, obtaining excellent results. The target molecular size distribution can be provided in tabulated form, allowing absolute freedom as to the types of chain size profiles that can be simulated. Distributions for which equilibration has been achieved here for linear polyethylene include a truncated most probable, a truncated Schulz-Zimm, an arbitrary one defined in tabulated form, a broad truncated Gaussian, and a bimodal Gaussian. The last two are comparable to those encountered in industrial applications. The impact of the molecular size distribution on the properties of the simulated melts, such as density, chain dimensions, and mixing thermodynamics, is explored.
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Affiliation(s)
- Dimitrios-Paraskevas Gerakinis
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "Demokritos," 15341 Athens, Greece
- School of Chemical Engineering, National Technical University of Athens, 9 Heroon Polytechniou Street, 15780 Athens, Greece
| | - Stefanos D Anogiannakis
- School of Chemical Engineering, National Technical University of Athens, 9 Heroon Polytechniou Street, 15780 Athens, Greece
- DPI, P.O. Box 902, 5600 AX Eindhoven, the Netherlands
| | - Doros N Theodorou
- School of Chemical Engineering, National Technical University of Athens, 9 Heroon Polytechniou Street, 15780 Athens, Greece
- DPI, P.O. Box 902, 5600 AX Eindhoven, the Netherlands
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Mukherji D, Kremer K. Smart Polymers for Soft Materials: From Solution Processing to Organic Solids. Polymers (Basel) 2023; 15:3229. [PMID: 37571124 PMCID: PMC10421237 DOI: 10.3390/polym15153229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 07/26/2023] [Accepted: 07/27/2023] [Indexed: 08/13/2023] Open
Abstract
Polymeric materials are ubiquitous in our everyday life, where they find a broad range of uses-spanning across common household items to advanced materials for modern technologies. In the context of the latter, so called "smart polymers" have received a lot of attention. These systems are soluble in water below their lower critical solution temperature Tℓ and often exhibit counterintuitive solvation behavior in mixed solvents. A polymer is known as smart-responsive when a slight change in external stimuli can significantly change its structure, functionm and stability. The interplay of different interactions, especially hydrogen bonds, can also be used for the design of lightweight high-performance organic solids with tunable properties. Here, a general scheme for establishing a structure-property relationship is a challenge using the conventional simulation techniques and also in standard experiments. From the theoretical side, a broad range of all-atom, multiscale, generic, and analytical techniques have been developed linking monomer level interaction details with macroscopic material properties. In this review, we briefly summarize the recent developments in the field of smart polymers, together with complementary experiments. For this purpose, we will specifically discuss the following: (1) the solution processing of responsive polymers and (2) their use in organic solids, with a goal to provide a microscopic understanding that may be used as a guiding tool for future experiments and/or simulations regarding designing advanced functional materials.
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Affiliation(s)
- Debashish Mukherji
- Quantum Matter Institute, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Kurt Kremer
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany;
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Kuété MA, Van Velthem P, Ballout W, Klavzer N, Nysten B, Ndikontar MK, Pardoen T, Bailly C. Eco-Friendly Blends of Recycled PET Copolymers with PLLA and Their Composites with Chopped Flax Fibres. Polymers (Basel) 2023; 15:3004. [PMID: 37514394 PMCID: PMC10384891 DOI: 10.3390/polym15143004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 07/04/2023] [Accepted: 07/06/2023] [Indexed: 07/30/2023] Open
Abstract
The structure and properties of blends of a novel polyethylene terephthalate copolymer (COPET) obtained by chemical recycling of commercial PET with high-molar-mass poly-L-lactide (PLLA) are investigated and compared to corresponding composites with chopped flax fibres. The focus is on the morphology at nano- and micro-scales, on the thermal characteristics and on the mechanical behaviour. The blends are immiscible, as evidenced by virtually unchanged glass transition temperatures of the blend components compared to the neat polymers (49 °C for COPET and 63 °C for PLLA by DSC). At low PLLA content, the blends display a sea-island morphology with sub-micron to micron droplet sizes. As the composition approaches 50/50, the morphology transitions to a coarser co-continuous elongated structure. The blends and composites show strongly improved stiffness compared to COPET above its glass transition temperature, e.g., from melt behaviour at 60 °C for COPET alone to almost 600 MPa for the 50/50 blend and 500 MPa for the 20% flax composite of the 80/20 COPET/PLLA blend. The flax fibres increase the crystallisation rate of PLLA in blends with dispersed PLLA morphology. The evidence of cavitation on the fracture surfaces of blends shows that despite the immiscibility of the components, the interfacial adhesion between the phases is excellent. This is attributed to the presence of aliphatic ester spacers in COPET. The tensile strength of the 80/20 blend is around 50 MPa with a Young's modulus of 2250 MPa. The corresponding 20% flax composite has similar tensile strength but a high Young's modulus equal to 6400 MPa, which results from the individual dispersion and strong adhesion of the flax fibres and leads close to the maximum possible reinforcement of the composite, as demonstrated by tensile tests and nano-indentation. The Ashby approach to eco-selection relying on the embodied energy (EE) further clarifies the eco-friendliness of the blends and their composites, which are even better positioned than PLLA in a stiffness versus EE chart.
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Affiliation(s)
- Martial Aimé Kuété
- Institute of Condensed Matter and Nanosciences-Bio & Soft Matter (IMCN/BSMA), UCLouvain, 1348 Louvain-la-Neuve, Belgium
- Institute of Mechanics, Materials and Civil Engineering, UCLouvain, 1348 Louvain-la-Neuve, Belgium
- Macromolecular Chemistry Unit, Applied Chemistry Laboratory, Faculty of Science, University of Yaoundé I, Yaoundé P.O. Box 812, Cameroon
| | - Pascal Van Velthem
- Institute of Condensed Matter and Nanosciences-Bio & Soft Matter (IMCN/BSMA), UCLouvain, 1348 Louvain-la-Neuve, Belgium
| | - Wael Ballout
- Institute of Condensed Matter and Nanosciences-Bio & Soft Matter (IMCN/BSMA), UCLouvain, 1348 Louvain-la-Neuve, Belgium
| | - Nathan Klavzer
- Institute of Mechanics, Materials and Civil Engineering, UCLouvain, 1348 Louvain-la-Neuve, Belgium
| | - Bernard Nysten
- Institute of Condensed Matter and Nanosciences-Bio & Soft Matter (IMCN/BSMA), UCLouvain, 1348 Louvain-la-Neuve, Belgium
| | - Maurice Kor Ndikontar
- Macromolecular Chemistry Unit, Applied Chemistry Laboratory, Faculty of Science, University of Yaoundé I, Yaoundé P.O. Box 812, Cameroon
| | - Thomas Pardoen
- Institute of Mechanics, Materials and Civil Engineering, UCLouvain, 1348 Louvain-la-Neuve, Belgium
| | - Christian Bailly
- Institute of Condensed Matter and Nanosciences-Bio & Soft Matter (IMCN/BSMA), UCLouvain, 1348 Louvain-la-Neuve, Belgium
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Amara U, Mahmood K, Khan M, Nawaz MH. Polypyrrole enwrapped binary metal oxides nanostructures for in-vitro Dopamine detection from lacrimal fluid. Microchem J 2023. [DOI: 10.1016/j.microc.2022.108254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Mkandawire WD, Milner ST. Pulling simulation predicts mixing free energy for binary mixtures. SOFT MATTER 2022; 18:7998-8007. [PMID: 36222173 DOI: 10.1039/d2sm01065h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Predicting the mixing free energy of mixing for binary mixtures using simulations is challenging. We present a novel molecular dynamics (MD) simulation method to extract the chemical potential μ(X) for mixtures of species A and B. Each molecule of species A and B is placed in equal and opposite harmonic potentials ±(1/2)Uex(x) centered at the middle of the simulation box, resulting in a nonuniform mole fraction profile X(z) in which A is concentrated at the center, and B at the periphery. Combining these, we obtain Uex(X), the exchange chemical potential required to induce a given deviation of the mole fraction from its average. Simulation results for Uex(X) can be fitted to simple free energy models to extract the interaction parameter χ for binary mixtures. To illustrate our method, we investigate benzene-pyridine mixtures, which provide a good example of regular solution behavior, using both TraPPE united-atom and OPLS all-atom potentials, both of which have been validated for pure fluid properties. χ values obtained with the new method are consistent with values from other recent simulation methods. However, the TraPPE-UA results differ substantially from the χ obtained from VLE experimental data, while the OPLS-AA results are in reasonable agreement with experiment, highlighting the importance of accurate potentials in correctly representing mixture behavior.
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Affiliation(s)
| | - Scott T Milner
- Pennsylvania State University, University Park, Pennsylvania, USA.
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Simon JM, Krüger P, Schnell SK, Vlugt TJH, Kjelstrup S, Bedeaux D. Kirkwood-Buff integrals: From fluctuations in finite volumes to the thermodynamic limit. J Chem Phys 2022; 157:130901. [PMID: 36209013 DOI: 10.1063/5.0106162] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The Kirkwood-Buff theory is a cornerstone of the statistical mechanics of liquids and solutions. It relates volume integrals over the radial distribution function, so-called Kirkwood-Buff integrals (KBIs), to particle number fluctuations and thereby to various macroscopic thermodynamic quantities such as the isothermal compressibility and partial molar volumes. Recently, the field has seen a strong revival with breakthroughs in the numerical computation of KBIs and applications to complex systems such as bio-molecules. One of the main emergent results is the possibility to use the finite volume KBIs as a tool to access finite volume thermodynamic quantities. The purpose of this Perspective is to shed new light on the latest developments and discuss future avenues.
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Affiliation(s)
- J-M Simon
- Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR-6303 CNRS - Université de Bourgogne Franche-Comté, F-21078 Dijon, France
| | - P Krüger
- Graduate School of Science and Engineering, Molecular Chirality Research Center, Chiba University, Chiba 263-8522, Japan
| | - S K Schnell
- Department of Materials Science and Engineering, NTNU - Norwegian University of Science and Technology, N-7491 Trondheim, Norway
| | - T J H Vlugt
- Process & Energy Department, Delft University of Technology, Leeghwaterstraat 39, 2628CB Delft, The Netherlands
| | - S Kjelstrup
- Center of Excellence PoreLab, Department of Chemistry, Faculty of Natural Sciences, NTNU - Norwegian University of Science and Technology, Trondheim, Norway
| | - D Bedeaux
- Center of Excellence PoreLab, Department of Chemistry, Faculty of Natural Sciences, NTNU - Norwegian University of Science and Technology, Trondheim, Norway
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