CHEMISTRY & CHEMICAL TECHNOLOGY Chem. Chem. Technol., 2021, Chemistry Vol. 15, No. 3, pp. 369–376 SYNTHESIS AND STRUCTURE OF UREA-FORMALDEHYDE OLIGOMERS WITH PEROXIDE GROUPS Olena Astakhova 1 , Olena Shyshchak 1 , Michael Bratychak 1, * https://doi.org/10.23939/chcht15.03.369 Abstract. 1 The possibility of synthesis in the presence of tert -butyl peroxymethanol (TBPM) or tert -butyl hydroperoxide (TBHP) of urea-formaldehyde oligomers with peroxide groups (UFOP) has been considered. Zinc oxide was used as the reaction catalyst. The effect of the initial components ratio, the reaction temperature and the process time on the characteristics and yield of the obtained oligomers was studied. Methods for obtaining UFOP using a mixture of TBPM and TBHP as a component are proposed. The structure of the synthesized UFOP was confirmed by IR- and NMR-spectroscopic studies. Keywords: urea, formaldehyde, urea-formaldehyde oligomers, peroxide, hydroperoxide, zinc oxide, IR- and NMR studies. 1. Introduction The expansion of the scope of polymeric materials in various industries, as well as the increased requirements for the operational properties of the products based on them, dictate the need to create new macromolecular compounds and improve the properties of existing ones [1-4]. The structure of most polymer systems and their compositions is formed in the presence of compounds capable to serve as a source of free radicals under certain temperature conditions [5]. There are, first of all, oligomeric compounds, which contain peroxide or hydroperoxide groups in their structure. Moreover, the presence of other functional groups in the molecules of such compounds, in addition to the –O–O– bond, makes it possible to control the processes of polymer production in order to create materials with given properties [5, 6]. Oligomers with peroxide groups, in comparison with low- molecular peroxides, are more stable during storage, less toxic and allow to form products by the so-called Lviv Polytechnic National University 12 Bandery St., Lviv 79013, Ukraine * mbratychak@gmail.com  Astakhova O., Shyshchak O., Bratychak M., 2021 "casting" technology. Epoxy [5, 7, 8], phenol- formaldehyde [9, 10] and polyglycedylphenol- formaldehyde oligomers [11] are most often used for the synthesis of mentioned oligomers. Epoxy resins are of special attention as starting compounds for the synthesis of peroxide oligomers. Epoxy resins are characterized by unique properties [12, 13] and contain reactive epoxy groups in their structure allowing to use resins as starting compounds for the synthesis of peroxide oligomers via the reaction of epoxy group with hydroperoxides and functional peroxides [6]. Apart from the above-mentioned functional resins, aminoformaldehyde compounds deserve special attention [14-17]. Such compounds are used for the creation of various polymer products. The raw materials for obtaining such oligomers are urea and formaldehyde. Therefore, such compounds, in comparison with the abovementioned ones, are quite cheap and available. At the same time, urea-formaldehyde resins are characterized by insufficient solubility in organic solvents and compatibility with other polymers, oligoesteracrylates in particular. This complicates the possibility of their widespread use for the creation of composites. On the other hand, the urea- formaldehyde oligomers contain free reactive methyl groups. This makes it possible to modify them with various low-molecular compounds and thus to extend the areas of their application. The paper considers the possibility of modifying urea-formaldehyde oligomers with functional peroxide (tert -butyl peroxymethanol and tert -butyl hydroperoxide) in order to introduce peroxide groups into the structure of urea-formaldehyde oligomers. Incomplete substitution of methylol groups for peroxide ones will allow to obtain products with both free methylol groups and peroxide groups. It means that such oligomers can be used in the process of products formation via both the polycondensation method using methylol groups and the polymerization mechanism using peroxide groups. The synthesized oligomers should show greater solubility in organic solvents and compatibility with other polymers.