SYNTHESIS OF THIOURETHANE OLIGOMER BASED ON ETHYLENE GLYCOL

ABSTRACT

Thiourethane oligomers are essential materials in various industrial applications due to their excellent mechanical properties, chemical resistance, and unique functionalities. The synthesis of thiourethane oligomers involves the reaction of thiourea and polyols, such as ethylene glycol, with isocyanates. This article explores the synthesis process, characterization, and potential applications of thiourethane oligomers based on ethyleneglycol.

АННОТАЦИЯ

Тиоуретановые олигомеры являются важными материалами в различных промышленных применениях благодаря их отличным механическим свойствам, химической стойкости и уникальным функциональным характеристикам. Синтез тиоуретановых олигомеров включает реакцию тиомочевины и полиолов, таких как этиленгликоль, с изоцианатами. В этой статье рассматриваются процесс синтеза, характеристика и потенциальные применения тиоуретановых олигомеров на основе этиленгликоля.

Keywords: thiourethane, oligomers, ethyleneglycol, gel permeation chromatography, cryoscopic constant, product, polymer.

Ключевые слова: тиоуретан, олигомеры, этиленгликоль, гель-проникающая хроматография, криоскопическая постоянная, продукт, полимер.

Introduction. The synthesis of thiourethane based on ethylene glycol, their molecular properties, and chemical reactions have been studied in numerous research papers in recent years. These thiourethanes are synthesized with the participation of ethylene glycol, formaldehyde, and thiourea. Thiourethanes are widely used in various fields, including polymer materials, coatings, and other specialty chemicals. Their main properties include high strength, chemical stability, and flexibility[1-3].

The synthesis of thiourethane oligomers based on ethylene glycol is a highly relevant topic in the field of polymer chemistry due to the unique properties and wide range of applications of these materials. Thiourethane oligomers exhibit exceptional mechanical properties, chemical resistance, and thermal stability, making them ideal for use in coatings, adhesives, sealants, and elastomers. The incorporation of ethylene glycol provides flexibility and enhances the polymer's ability to form strong, durable films[4-6]. Additionally, these oligomers can be tailored to possess specific functionalities, allowing for their use in advanced applications such as biomedical devices and high-performance materials. The process of synthesizing thiourethane oligomers involves reacting thiourea with ethylene glycol and isocyanates, leading to the formation of a robust polymer network. Research in this area is crucial for developing new materials with improved performance characteristics, meeting the increasing demands of various industries, including automotive, construction, and healthcare. The exploration of thiourethane oligomers not only advances scientific knowledge but also drives innovation in material science, making it a significant area of study[7-9].

Materials and methods. In the first step of oligomer synthesis involving urethane groups based on ethylene glycol, a chemical reaction is carried out between thiourea and ethylene glycol. The chemical reaction proceeds according to the following equation (Figure 1). The reaction results in ethylene glycol-based diurethane.

Figure 1. Results

• Reactants: Thiourea,Ethylene glycol
• Product: Diurethane based on ethylene glycol, Ammonia

In the second stage of synthesizing a urethane oligomer based on ethylene glycol, the previously obtained diurethane reacts with formaldehyde. The chemical condensation reaction of formaldehyde follows the scheme shown in Figure 2

The first stage of synthesizing thiourethane based on ethylene glycol (process of synthesizing diurethane based on ethylene glycol). A flask equipped with a laboratory stirrer, a reflux condenser, a dropping funnel, and a thermometer is charged with 78 grams of thiourea. The flask is heated to 80 ⁰C and stirred at a speed of 120 revolutions per minute. While stirring the thiourea, 62 grams of ethylene glycol heated to 130-140 ⁰C is added. When the hot ethylene glycol is added, the temperature of the reaction mass rises to 125-130 ⁰C. The ethylene glycol must be added at such a rate that the temperature of the reaction mass remains between 120 ⁰C and 130 ⁰C. After adding the entire designated amount of ethylene glycol, the temperature of the reaction system is raised to 140 ⁰C. At this temperature, the chemical reaction is carried out for 90 minutes. During the chemical reaction, ammonia gas is observed to evolve from the reaction mass. The release of ammonia can be detected using moist litmus paper. At the end of the reaction between thiourea and ethylene glycol, the release of ammonia decreases. After the reaction is complete, the temperature is slowly lowered to 80 ⁰C and the light brown viscous liquid mass is held at 70 - 80 ⁰C for 25 – 30 minutes.

Results and discussion. The cryoscopic indicators of the solutions of the obtained diurethane based on ethylene glycol have been determined. Based on the results obtained from the cryoscopic method of study, Table 1 was compiled. The table shows the changes in the crystallization temperature of the solutions of the obtained diurethane based on ethylene glycol at concentrations of 2.5; 3, 3,5 and 4 as well as the molecular mass M. Based on the obtained data, a graph of the dependence of the molecular mass M  on the concentrations of the corresponding solutions was constructed (Figure 3).

Table 1

The results of calculations of the cryoscopic analysis method for the derivative reaction of the interaction of ethylene glycol with thiourea

Designations: 𝑚₁– mass of the dissolved oligourethane, g; 𝑚₂– mass of the solvent, g; 𝐶– concentration of the solution, %; 𝑇c𝑜– crystallization temperature of the solvent, °C; 𝑇c𝑟– crystallization temperature of the solution, °C; Δ𝑇 – temperature depression; 𝑀– molecular mass of the urethane-containing oligomer.

Figure 3. Diagram of the molecular weight dependence of the product of the interaction reaction between ethylene glycol and thiourea on the concentration of the solvent

Conclusion. Thus, based on the obtained results, it can be concluded that the developed isocyanate-free synthesis method for urethane oligomers based on ethyleneglycol allows obtaining oligourethanes with an average molecular weight of 900-1050. The optimal temperatures for the chemical reaction stages of the synthesis and the duration of each stage have been established.

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