Research

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10 pages, 1584 KiB

Open AccessArticle

Temperature Dependence of the Number of Defect-Structures in Poly(vinylidene fluoride)

by Jan Schwaderer, Marco Drache and Sabine Beuermann

Molecules 2024, 29(7), 1551; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29071551 - 29 Mar 2024

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Poly(vinylidene fluoride) (PVDF) is predominantly characterized by alternating CH₂ and CF₂ units in a polymer backbone, originating from the head-to-tail addition of monomers or regular propagation. Due, to a small extent, to inverse monomer addition, so-called defect structures occur which influence [...] Read more.

Poly(vinylidene fluoride) (PVDF) is predominantly characterized by alternating CH₂ and CF₂ units in a polymer backbone, originating from the head-to-tail addition of monomers or regular propagation. Due, to a small extent, to inverse monomer addition, so-called defect structures occur which influence the macroscopic properties of PVDF significantly. The amount of defect structures in the material is determined by the polymerization conditions. Here, the temperature dependence of the fraction of defect structures in PVDF obtained from polymerizations between 45 and 90 °C is reported. We utilized ¹⁹F-NMR spectroscopy to determine the fraction of defect structures as a function of temperature. To derive kinetic data, the polymerization of VDF is considered a quasi-copolymerization described by the Terminal Model involving four different propagation reactions. Based on the experimentally determined temperature-dependent fractions of defect structures, the known overall propagation rate coefficient, and taking into account the self-healing behavior of the macroradical, the Arrhenius parameters of the individual propagation rate coefficients were determined using the Monte Carlo methods. Full article

(This article belongs to the Special Issue Themed Issue Dedicated to Prof. Bernard Boutevin)

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10 pages, 2010 KiB

Open AccessArticle

Nitroxide-Mediated Controlled Radical Copolymerization of α-Trifluoromethylstyrenes with Styrenes

by Tadashi Kanbara, Yuriko Ito, Airi Yamaguchi and Tomoko Yajima

Molecules 2024, 29(6), 1214; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29061214 - 08 Mar 2024

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Abstract

Fluorinated polymers are important materials in everyday life; however, most monomers of widely used fluoropolymers are gaseous, and their polymerization is difficult in an ordinary laboratory. Therefore, partially fluorinated polymers have recently been reported. As an easy-to-handle fluorine-containing monomer, α-trifluoromethylstyrene (TFMST) can be [...] Read more.

Fluorinated polymers are important materials in everyday life; however, most monomers of widely used fluoropolymers are gaseous, and their polymerization is difficult in an ordinary laboratory. Therefore, partially fluorinated polymers have recently been reported. As an easy-to-handle fluorine-containing monomer, α-trifluoromethylstyrene (TFMST) can be used to produce partially fluorinated polymers with trifluoromethyl groups in the main chain; however, TFMST does not homopolymerize, and there are limited reports on its copolymerization with styrene (ST). In this study, we applied the controlled radical polymerization method, which is effective for the polymerization of ST, to the copolymerization of TFMST and ST. We also showed that nitroxide-mediated polymerization is effective. The content ratio of TFMST in the TFMST–ST copolymer can be controlled between 10% and 40% by changing its monomer ratio. Additionally, the polymerization of TFMST and ST with substituents was performed to increase structural variations. The thermal stability as well as water and oil repellency of the synthesized polymers with different composition ratios and substituents were also evaluated. Full article

(This article belongs to the Special Issue Themed Issue Dedicated to Prof. Bernard Boutevin)

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13 pages, 2401 KiB

Open AccessArticle

Incorporation of Aramids into Polybenzimidazoles to Achieve Ultra-High Thermoresistance and Toughening Effects

by Xianzhu Zhong, Aniruddha Nag, Kenji Takada, Akinori Nakajima and Tatsuo Kaneko

Molecules 2024, 29(5), 1058; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29051058 - 28 Feb 2024

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Abstract

Polybenzimidazoles (PBIs) are recognized for their remarkable thermal stability due to their unique molecular structure, which is characterized by aromaticity and rigidity. Despite their remarkable thermal attributes, their tensile properties limit their application. To improve the mechanical performance of PBIs, we made a [...] Read more.

Polybenzimidazoles (PBIs) are recognized for their remarkable thermal stability due to their unique molecular structure, which is characterized by aromaticity and rigidity. Despite their remarkable thermal attributes, their tensile properties limit their application. To improve the mechanical performance of PBIs, we made a vital modification to their molecular backbone to improve their structural flexibility. Non-π-conjugated components were introduced into PBIs by grafting meta-polyamide (MA) and para-polyamide (PA) onto PBI backbones to form the copolymers PBI-co-MA and PBI-co-PA. The results indicated that the cooperation between MA and PA significantly enhanced mechanical strain and overall toughness. Furthermore, the appropriate incorporation of aromatic polyamide components (20 mol% for MA and 15% for PA) improved thermal degradation temperatures by more than 30 °C. By investigating the copolymerization of PBIs with MA and PA, we unraveled the intricate relationships between composition, molecular structure, and material performance. These findings advance copolymer design strategies and deepen the understanding of polymer materials, offering tailored solutions that address thermal and mechanical demands across applications. Full article

(This article belongs to the Special Issue Themed Issue Dedicated to Prof. Bernard Boutevin)

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15 pages, 3257 KiB

Open AccessArticle

A One-Step Approach for a Durable and Highly Hydrophobic Coating for Flax Fabrics for Self-Cleaning Application

by Antoine Ishak, Rodolphe Sonnier, Belkacem Otazaghine and Claire Longuet

Molecules 2024, 29(4), 829; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29040829 - 13 Feb 2024

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Abstract

Highly hydrophobic flax fabrics with durable properties were prepared using the “dip-coating” method for self-cleaning application. Flax fabrics were coated with a polysiloxane coating via a hydrosilylation reaction with a Karstedt catalyst at room temperature. The coated fabrics displayed highly and durable hydrophobic [...] Read more.

Highly hydrophobic flax fabrics with durable properties were prepared using the “dip-coating” method for self-cleaning application. Flax fabrics were coated with a polysiloxane coating via a hydrosilylation reaction with a Karstedt catalyst at room temperature. The coated fabrics displayed highly and durable hydrophobic properties (contact angle and sliding angle of about 145° and 23°, respectively) with good self-cleaning ability for certain pollutants and excellent durability. Moreover, the influence of the coating process on the mechanical properties of fabrics was investigated. A decrease in E modulus and an increase in tensile stress at maximum force and elongation at maximum force has been observed. Furthermore, this influence of the coating process can be easily controlled by adjusting the proportion of curing agent in the treatment solution. Full article

(This article belongs to the Special Issue Themed Issue Dedicated to Prof. Bernard Boutevin)

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19 pages, 4562 KiB

Open AccessArticle

The Effect of Block Ratio and Structure on the Thermosensitivity of Double and Triple Betaine Block Copolymers

by Jongmin Lim, Hideki Matsuoka, Yusuke Kinoshita, Shin-ichi Yusa and Yoshiyuki Saruwatari

Molecules 2024, 29(2), 390; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29020390 - 12 Jan 2024

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Abstract

AB-type and BAB-type betaine block copolymers composed of a carboxybetaine methacrylate and a sulfobetaine methacrylate, PGLBT-b-PSPE and PSPE-b-PGLBT-b-PSPE, respectively, were synthesized by one-pot RAFT polymerization. By optimizing the concentration of the monomer, initiator, and chain transfer agent, [...] Read more.

AB-type and BAB-type betaine block copolymers composed of a carboxybetaine methacrylate and a sulfobetaine methacrylate, PGLBT-b-PSPE and PSPE-b-PGLBT-b-PSPE, respectively, were synthesized by one-pot RAFT polymerization. By optimizing the concentration of the monomer, initiator, and chain transfer agent, block extension with precise ratio control was enabled and a full conversion (~99%) of betaine monomers was achieved at each step. Two sets (total degree of polymerization: ~300 and ~600) of diblock copolymers having four different PGLBT:PSPE ratios were prepared to compare the influence of block ratio and molecular weight on the temperature-responsive behavior in aqueous solution. A turbidimetry and dynamic light scattering study revealed a shift to higher temperatures of the cloud point and micelle formation by increasing the ratio of PSPE, which exhibit upper critical solution temperature (UCST) behavior. PSPE-dominant diblocks created spherical micelles stabilized by PGLBT motifs, and the transition behavior diminished by decreasing the PSPE ratio. No particular change was found in the diblocks that had an identical AB ratio. This trend reappeared in the other set whose entire molecular weight approximately doubled, and each transition point was not recognizably impacted by the total molecular weight. For triblocks, the PSPE double ends provided a higher probability of interchain attractions and resulted in a more turbid solution at higher temperatures, compared to the diblocks which had similar block ratios and molecular weights. The intermediates assumed as network-like soft aggregates eventually rearranged to monodisperse flowerlike micelles. It is expected that the method for obtaining well-defined betaine block copolymers, as well as the relationship of the block ratio and the chain conformation to the temperature-responsive behavior, will be helpful for designing betaine-based polymeric applications. Full article

(This article belongs to the Special Issue Themed Issue Dedicated to Prof. Bernard Boutevin)

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15 pages, 2883 KiB

Open AccessFeature PaperArticle

Original Fluorinated Non-Isocyanate Polyhydroxyurethanes

by Lolwa Haydar, Wassim El Malti, Vincent Ladmiral, Ali Alaaeddine and Bruno Ameduri

Molecules 2023, 28(4), 1795; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules28041795 - 14 Feb 2023

Cited by 2 | Viewed by 1435

Abstract

New fluorinated polyhydroxyurethanes (FPHUs) with various molar weights were synthesized via the polyaddition reaction of a fluorinated telechelic bis(cyclocarbonate) (bis-CC) with a diamine. The fluorinated bis-CC was initially synthesized by carbonylation of a fluorinated diepoxide, 1,4-bis(2′,3′-epoxypropyl)perfluorobutane, in the presence of LiBr catalyst, in [...] Read more.

New fluorinated polyhydroxyurethanes (FPHUs) with various molar weights were synthesized via the polyaddition reaction of a fluorinated telechelic bis(cyclocarbonate) (bis-CC) with a diamine. The fluorinated bis-CC was initially synthesized by carbonylation of a fluorinated diepoxide, 1,4-bis(2′,3′-epoxypropyl)perfluorobutane, in the presence of LiBr catalyst, in high yield. Then, several reaction conditions were optimized through the model reactions of the fluorinated bis-CC with hexylamine. Subsequently, fluorinated polymers bearing hydroxyurethane moieties (FPHUs) were prepared by reacting the bis-CC with different hexamethylenediamine amounts in bulk at 80 °C and the presence of a catalyst. The chemoselective polymerization reaction yielded three isomers bearing primary and secondary hydroxyl groups in 61–82% yield. The synthesized fluorinated CCs and the corresponding FPHUs were characterized by ¹H, ¹⁹F, and ¹³C NMR spectroscopy. They were compared to their hydrogenated homologues synthesized in similar conditions. The gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) data of the FPHUs revealed a higher molar mass and a slight increase in glass transition and decomposition temperatures compared to those of the PHUs. Full article

(This article belongs to the Special Issue Themed Issue Dedicated to Prof. Bernard Boutevin)

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9 pages, 618 KiB

Open AccessArticle

Using Triethylborane to Manipulate Reactivity Ratios in Epoxide-Anhydride Copolymerization: Application to the Synthesis of Polyethers with Degradable Ester Functions

by Vamshi K. Chidara, Yves Gnanou and Xiaoshuang Feng

Molecules 2022, 27(2), 466; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules27020466 - 11 Jan 2022

Cited by 8 | Viewed by 2493

Abstract

The anionic ring-opening copolymerization (ROCOP) of epoxides, namely of ethylene oxide (EO), with anhydrides (AH) generally produces strictly alternating copolymers. With triethylborane (TEB)-assisted ROCOP of EO with AH, statistical copolymers of high molar mass including ether and ester units could be obtained. In [...] Read more.

The anionic ring-opening copolymerization (ROCOP) of epoxides, namely of ethylene oxide (EO), with anhydrides (AH) generally produces strictly alternating copolymers. With triethylborane (TEB)-assisted ROCOP of EO with AH, statistical copolymers of high molar mass including ether and ester units could be obtained. In the presence of TEB, the reactivity ratio of EO (r_EO), which is normally equal to 0 in its absence, could be progressively raised to values lower than 1 or higher than 1. Conditions were even found to obtain r_EO equal or close to 1. Samples of P(EO-co-ester) with minimal compositional drift could be synthesized; upon basic degradation of their ester linkages, these samples afforded poly(ethylene oxide) (PEO) diol samples of narrow molar mass distribution. In other cases where r_EO were lower or higher than 1, the PEO diol samples eventually isolated after degradation exhibited a broader distribution of molar masses because of the compositional drift of initial P(EO-co-ester) samples. Full article

(This article belongs to the Special Issue Themed Issue Dedicated to Prof. Bernard Boutevin)

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Review

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26 pages, 5758 KiB

Open AccessFeature PaperReview

Monomers and Macromolecular Materials from Renewable Resources: State of the Art and Perspectives

by Alessandro Gandini and Talita M. Lacerda

Molecules 2022, 27(1), 159; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules27010159 - 28 Dec 2021

Cited by 18 | Viewed by 3295

Abstract

A progressively increasing concern about the environmental impacts of the whole polymer industry has boosted the design of less aggressive technologies that allow for the maximum use of carbon atoms, and reduced dependence on the fossil platform. Progresses related to the former approach [...] Read more.

A progressively increasing concern about the environmental impacts of the whole polymer industry has boosted the design of less aggressive technologies that allow for the maximum use of carbon atoms, and reduced dependence on the fossil platform. Progresses related to the former approach are mostly based on the concept of the circular economy, which aims at a thorough use of raw materials, from production to disposal. The latter, however, has been considered a priority nowadays, as short-term biological processes can efficiently provide a myriad of chemicals for the polymer industry. Polymers from renewable resources are widely established in research and technology facilities from all over the world, and a broader consolidation of such materials is expected in a near future. Herein, an up-to-date overview of the most recent and relevant contributions dedicated to the production of monomers and polymers from biomass is presented. We provide some basic issues related to the preparation of polymers from renewable resources to discuss ongoing strategies that can be used to achieve original polymers and systems thereof. Full article

(This article belongs to the Special Issue Themed Issue Dedicated to Prof. Bernard Boutevin)

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