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Studies on Thermosetting Resin Blends: Bispropargyl Ether-Bismaleimide
Published in Didier Rouxel, Sabu Thomas, Nandakumar Kalarikkal, Sajith T. Abdulrahman, Advanced Polymeric Materials, 2022
J. Dhanalakshmi, K. G. Sudhamani, C. T. Vijayakumar
Picklesimer [16] prepared phenolic materials containing propargyl groups in short reaction periods by the reaction of a polyhydric phenolic material with propargyl bromide, the reaction being conducted in an aqueous sodium hydroxide solution. The process suffers from the disadvantage of providing both O-propargylated (desired) and C-propargylated (undesired) materials (Figure 2.4). For example, bisphenol-A is claimed to provide a 45.4% yield of the desired bispropargyl ether and a 43.6% yield of the undesired C-propargylated bisphenol. Additionally, the process employs rather vigorous conditions, such as reflux conditions of 100°C, for 1–3 h. A further drawback of the process is that propargyl bromide is used rather than propargyl chloride. The bromide is a relatively expensive inaccessible compound on a commercial scale and it is shock-sensitive.
Amphiphiles from Poly(3-hydroxyalkanoates)
Published in Martin Koller, The Handbook of Polyhydroxyalkanoates, 2020
Poly(3-hydroxyoctanoate-co-3-hydroxyundecenoate) (PHOU) is methanolyzed and its unsaturated side chains are quantitatively oxidized to carboxylic acid. Alkyne-containing “clickable” PHA is obtained by the esterification with propargyl alcohol [50]. A click reaction of propargyl terminated PHOU with the azide terminated PEG leads to a PHOU-PEG graft copolymer. Figure 3.6 renders the synthesis of a PHOU-g-PEG graft copolymer using an azide-acetylene click reaction. Synthesis of PHOU-g-PEG graft copolymer using azide-acetylene click reaction [50].
Properties of Liquid Crystalline Thermosets and Their Nanocomposites
Published in Robert R. Luise, of High Temperature Polymers, 1997
Elliot P. Douglas, David A. Langlois, Mark E. Smith, Rex P. Hjelm, Brian C. Benicewicz
The general structure of ester LCTs is shown in Figure 3. A greater variety of esters has been prepared than of amides. Only a few representative examples are discussed here; more detailed discussions are available in our previous publications.5,19 In all cases the esters are prepared by reacting two equivalents of an appropriate acid chloride with a diol, usually substituted hydroquinone. With suitable care these condensation reactions are quantitative. For the maleimide, nadimide, and methylnadimide end groups the acid chlorides are prepared in the same way as the amide LCTs. For acetylene LCTs the p-ethynyl benzoyl chloride was purchased from Ballard Advanced Materials, but could also be prepared according to the procedure of Melissaris and Litt.20 For propargyl LCTs the end group is prepared by a modification of the procedure described by Dirlikov.21 Methyl-4-hydroxybenzoate is reacted with a slight excess of propargyl chloride in the presence of potassium carbonate to yield methyl-4-propargylbenzoate. This product is then converted to the acid chloride in two steps. Alternatively, propargyl LCTs can be prepared by reacting propargyl chloride directly with a diol in the presence of potassium carbonate. In this case the resulting thermoset has the propargyl group attached directly to the central mesogenic unit and does not contain an ester group. We have also prepared mixed propargyl thermosets in which one end is derived from the 4-propargylbenzoyl chloride and the other is derived from propargyl chloride, resulting in a thermoset with only one ester group.
First isoflavone-based hexacatenar derivatives with columnar liquid crystalline self-assembly and binding selectivity behavior
Published in Soft Materials, 2023
Nana Li, Xiaoling Xie, Sha Wang, Xiaoqin Yi, Jun Leng, Zhongwen Sun, Zonglin Jiang
The chemical structures and synthetic route designed for the isoflavone-based hexacatenars takes advantage of click reaction between terminal alkyne and azide as shown in Scheme 1. Isoflavone 1 was synthesized according to the literature,[16] and then isoflavone was etherified with propargyl bromide to yield the key intermediate bispropargylether 2. The 3,4,5-trialkoxybenzyl azides 3/n were reported in our previous literature.[51] Click reaction between 2 and 3/n yields the target compounds D/n in 84–91% yield. The intermediates and target compounds were purified by column chromatography and characterized by 1H NMR and 13C NMR. The detailed synthesis procedures and corresponding data are given in the Supporting Information.
EUROCORR 2020: ‘closing the gap between industry and academia in corrosion science and prediction’: part 4
Published in Corrosion Engineering, Science and Technology, 2021
D. J. Mills (University of Nottingham, UK) addressed, ‘Exploring green corrosion inhibitors using electrochemical noise measurements of corrosion in acidic conditions.’ ‘Green’ corrosion inhibitors derived from plant materials such as henna leaves, celery seeds and banana skins, provide alternatives to conventional corrosion inhibitors. Certain extracts contain electron-rich polar atoms, e.g. N, O, S and P which confer inhibition. However, it is difficult to predict effective reagents on a molecular basis. Electrochemical noise (ECN), a quick and non-invasive method, using the natural fluctuations that occur during corrosion, was used. Corrosion rates could be derived from Resistance noise (Rn). The instrument used (ProCoMeter) is an improvement on hitherto conventional methods. The corrosion of mild steel in 1 M HCl (typically used in the pickling industry) at room temperature, was studied. A comparison between using propargyl alcohol and using broccoli extract was reported.
Enhancement of the bending strength of I-shaped cross-sectional beam of CFRP by dispersing cellulose nanofibers without hydrophobic treatment on the surface
Published in Mechanics of Advanced Materials and Structures, 2021
Kazuaki Katagiri, Shinya Honda, Sayaka Minami, Shimpei Yamaguchi, Hirosuke Sonomura, Ozaki Tomoatsu, Sonomi Kawakita, Sohei Uchida, Masayuki Nezu, Mamoru Takemura, Yayoi Yoshioka, Katsuhiko Sasaki
An electro-activated deposition solution for precipitating an epoxy resin on the cathode, INSULEED 3030 (Nippon Paint Co., Ltd., Japan) was selected [16]. This solution is an aqueous system, which contains a sulfonium salt of polymer with epoxy groups and propargyl alcohol. A sulfonium reduction precipitation occurs and epoxy is precipitated on the cathode side by energization. It is believed that sulfur is interposed between the carbon and resin (vulcanizing bond). Therefore, unlike conventional electrodeposition solution, a blocking agent to prevent chemical reaction in the solution to separate an epoxy resin prepolymer and a curing agent is unnecessary. Thus, no void was generated due to the evaporation of the blocking agent, and there is no emission of VOC which becomes air pollutant. No metal catalyst is used in the electro-activated deposition reaction.