The chain tacticity of a polymer is a key influence on its structure and dynamics, which ultimately determine its properties. While they have great potential to elucidate the influence of chain tacticity, all-atom molecular simulations are often restricted to short chains and small systems. In this work, two typical stereoregular poly(methyl methacrylate) melts were investigated via multiscale simulations. To improve computational efficiency, systematic coarse-graining was first performed. While the coarse-grained molecular dynamics simulations were able to show the effects of tacticity on intramolecular structure and intermolecular interactions, they were not able to reproduce the exact structural distribution or even the effects of tacticity on the dynamics. An alternative reverse-mapping scheme was therefore developed specifically to treat chain configurations in a direct geometric way. The backmapped all-atomistic simulations were found to accurately reproduce the microscopic features of the polymers. Since the effects of tacticity are rather subtle and therefore difficult to discern, this multiscale simulation scheme is a very important method of investigating complex high molecular weight polymer systems.
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http://dx.doi.org/10.1007/s00894-014-2377-3 | DOI Listing |
Molecules
January 2025
Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland.
Building on our previous studies, which have demonstrated that homochiral propagating species-(*,*)-[MeGa(-OCH(Me)COR)]-were crucial for the heteroselectivity of [MeGa(-OCH(Me)COMe)] in the ring-opening polymerization (ROP) of racemic lactide (-LA), we have investigated the effect of alkyl groups on the structure and catalytic properties of dialkylgallium alkoxides in the ROP of -LA. Therefore, we have isolated and characterized the -[RGa(-OCH(Me)COMe] (R = Et (), Pr () and -[RGa(-OCH(Me)CHN] (R = Et (), Pr ()) complexes, to demonstrate the effect of alkyl groups on the chiral recognition induced the formation of the respective homochiaral species-(*,*)-[RGa(-OCH(Me)COMe)] and (*,*)-[RGa(-OCH(Me)CHN]. Moreover, we have investigated the structure of (,)-[RGa(-OCH(Me)COMe] (R = Et ((,)-, R = Pr ((,)-,) and their catalytic activity in the ROP of -LA.
View Article and Find Full Text PDFInorg Chem
May 2024
Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China.
The stereoselective polymerization of polar vinyl monomers has recently received much attention due to their excellent physicochemical properties. Over the past decade, breakthroughs have been achieved in this field by rare-earth catalysts. However, the mechanistic origins of those stereoselective polymerizations still remain unclear.
View Article and Find Full Text PDFACS Catal
September 2023
Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, United States.
The synthesis of stereoregular polymers through ionic mechanisms using asymmetric ion-pairing (AIP) catalysis is emerging as an effective strategy to achieve differentiated material properties from readily available building blocks. Stereoselective cationic polymerization in particular is primed for advancement using AIP by leveraging the breadth of Brønsted and Lewis acid small-molecule catalysis literature; however, mechanistic studies that address polymer-specific phenomena are scarce and, as a result, the lack of mechanistic understanding has limited catalyst design. In a recent study, we demonstrated the only example of a stereoselective and helix-sense-selective cationic vinyl polymerization of -vinylcarbazole using chiral scandium-(oxazoline) Lewis acids.
View Article and Find Full Text PDFNanoscale
January 2024
Key Laboratory of Rubber-Plastics, Ministry of Education/Shandong Provincial Key Laboratory of Rubber-Plastics, Qingdao University of Science & Technology, Qingdao City 266042, People's Republic of China.
Adhesive hydrogels (AHs) are considered ideal materials for flexible sensors. However, the lack of effective energy dissipation networks and sparse surface polar groups in AHs lead to poor mechanical properties and interfacial adhesion, which limit their practical application. Herein, a tough, long-lasting adhesive and highly conductive nanocomposite hydrogel (PACPH) was fabricated the synergy of interfacial entanglement and adhesion group densification.
View Article and Find Full Text PDFSci Rep
December 2023
Integrated Biomedical Sciences (IBMS) Program, The School of Medicine, The University of Texas Health Science Center at San Antonio (UTHSCSA), 7703 Floyd Curl Drive, San Antonio, TX, 78229-3900, USA.
Gene plasticity during myogenous temporomandibular disorder (TMDM) development is largely unknown. TMDM could be modeled by intramuscular inflammation or tissue damage. To model inflammation induced TMDM we injected complete Freund's adjuvant (CFA) into masseter muscle (MM).
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