POSS-Based Functional Nanomaterials, Composites, and Additives

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Smart and Functional Polymers".

Deadline for manuscript submissions: closed (15 June 2023) | Viewed by 4282

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Nanoscience Department, University of North Carolina Greensboro, Greensboro, NC 27412, USA
Interests: organic–inorganic hybrid materials; functional nanomaterials; self-assembly; polymers and polymer composites; environmental remediation and sustainability
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Special Issue Information

Dear Colleagues,

Polyhedral oligomeric silsesquioxanes (POSSs) have been used over the past few decades for a variety of applications, including as functional materials in optoelectronics, lightweight structures, and additive manufacturing. Moreover, among the significant advances made towards their use in fuel cells, optical devices, sensors, optoelectronics, solar energy harvesting, and thermoelectric devices, the POSS family is predicted to have high demand due to their capability in functional tunability via ligand-tailoring chemistry and having rigid and thermally stable silsesquioxane core structure. Thus, these hybrid structures have been incorporated into a variety of materials to enhance their properties, such as thermal stability, optical transparency, toughness, and solubility.

POSSs are specifically classified as cubic T8 silsesquioxanes, which consist of a rigid, crystalline silica-like core that has a perfectly defined atomic spatiality in the range of 0.5–0.7 nm, and the core is linked covalently to eight R groups. Depending on the number of repetitive units in the general formula (RSiO1.5)n (n = 4, 6, 8, and 10–16), there are different types of Tn silsesquioxane structures, which also belong to POSS family. In addition to fully condensed Tn silsesquioxane structures with n = 4, 6, 8, 10, 12, 14, and 16, incompletely condensed structures containing Si–OH groups are known, which have the generic formula [R–SiO1.5−x(OH)2x]n or Tn(OH)m. Thus, the structures of POSS family include perfect polyhedra, incompletely condensed polyhedra (species with 1–3 OH per molecule), ladder-type structures (species with 4 OH per molecule), open structures (species with more than 5 OH per molecule), linear structures, and all their possible combinations. For example, POSSs with functionalizable sites at silicon vertices wherein the number of reactive sites can be varied from 1 to 8 can yield an entire class of silicon-based organic–inorganic hybrid materials with a POSS incorporated as the central core in dendrimers and hyperbranched polymers, as well as pendants on polymer chains.

The aim of this Special Issue is to highlight the progress on the synthesis, characterization, properties, and applications of functional POSSs and POSS-based composites, additives, and nanomaterials.

Dr. Hemali Rathnayake
Guest Editor

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Keywords

  • POSS
  • polysilsesquioxanes
  • POSS nanomaterials
  • POSS composites
  • POSS additives
  • silsesquioxanes
  • silicon-based hybrids
  • POSS dendrimers
  • POSS hyperbranched polymers

Published Papers (2 papers)

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Research

24 pages, 14686 KiB  
Article
Unlocking the Potential Use of Reactive POSS as a Coagent for EPDM/PP-Based TPV
by Nazlı Yazıcı Çakır, Özgenur İnan, Merve Ergün, Mehmet Kodal and Güralp Özkoç
Polymers 2023, 15(10), 2267; https://doi.org/10.3390/polym15102267 - 11 May 2023
Cited by 3 | Viewed by 2003
Abstract
Thermoplastic vulcanizates (TPVs) are multifunctional materials consisting of two or more phases with solid elastomeric properties at room temperatures and fluid-like properties above their melting point. They are produced through a reactive blending process known as dynamic vulcanization. The most widely produced TPV [...] Read more.
Thermoplastic vulcanizates (TPVs) are multifunctional materials consisting of two or more phases with solid elastomeric properties at room temperatures and fluid-like properties above their melting point. They are produced through a reactive blending process known as dynamic vulcanization. The most widely produced TPV type is ethylene propylene diene monomer/polypropylene (EPDM/PP), which is the focus of this study. The peroxides are mainly selected to be used in crosslinking of EPDM/PP-based TPV. However, they still have some disadvantages, such as the side reactions resulting in the beta chain scission of the PP phase and undesired disproportionation reactions. To eliminate these disadvantages, coagents are used. In this study, for the first time, the use of vinyl functionalized polyhedral oligomeric silsesquioxane (OV-POSS) nanoparticles was investigated as a potential coagent in EPDM/PP-based TPV production via peroxide-initiated dynamic vulcanization. The properties of the TPVs having POSS were compared with the conventional TPVs containing conventional coagents, such as triallyl cyanurate (TAC). POSS content and EPDM/PP ratio were investigated as the material parameters. Mechanical properties of EPDM/PP TPVs exhibited higher values in the presence of OV-POSS, which resulted from the active participation of OV-POSS into the three-dimensional network structure of EPDM/PP during dynamic vulcanization. Full article
(This article belongs to the Special Issue POSS-Based Functional Nanomaterials, Composites, and Additives)
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14 pages, 8648 KiB  
Article
Synthesis of a Novel Bifunctional Epoxy Double-Decker Silsesquioxane: Improvement of the Thermal Stability and Dielectric Properties of Polybenzoxazine
by Xiaoyi Sun, Jing Wang, Qixuan Fu, Qian Zhang and Riwei Xu
Polymers 2022, 14(23), 5154; https://doi.org/10.3390/polym14235154 - 26 Nov 2022
Cited by 7 | Viewed by 1813
Abstract
In this study a new type of bifunctional epoxy compound (DDSQ-EP) based on double-decker silsesquioxane (DDSQ) was synthesized by process of alkaline hydrolysis condensation of phenyltrimethoxysilane and corner capping reaction with dichloromethylvinylsilane, followed by epoxidation reaction of vinyl groups. The resultant structures were [...] Read more.
In this study a new type of bifunctional epoxy compound (DDSQ-EP) based on double-decker silsesquioxane (DDSQ) was synthesized by process of alkaline hydrolysis condensation of phenyltrimethoxysilane and corner capping reaction with dichloromethylvinylsilane, followed by epoxidation reaction of vinyl groups. The resultant structures were confirmed using Fourier transform infrared spectrometry, nuclear magnetic resonance spectrometry and time-of-flight mass spectrometry, respectively. The DDSQ-EP was incorporated into polybenzoxazine to obtain the PBZ/DDSQ-EP nanocomposites. The uniform dispersion of DDSQ-EP in the nanocomposites was verified by X-ray diffraction and scanning electron microscope. The reactions occurred during the curing of the composites and were investigated using infrared spectroscopy of segmented cures. Dynamic mechanical analysis and thermal gravimetric analysis indicated that the storage modulus, glass transition temperature and thermal stability of PBZ/DDSQ-EP were increased in comparison with pure benzoxazine resins. Assessment of dielectric properties demonstrated that the dielectric permittivity and dielectric loss of polybenzoxazine decreased slightly because of the addition of DDSQ-EP. Full article
(This article belongs to the Special Issue POSS-Based Functional Nanomaterials, Composites, and Additives)
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