Functional Modification Effect of Epoxy Oligomers on the Structure and Properties of Epoxy Hydroxyurethane Polymers

Abstract

We introduce different ways to solve the actual fragility problem of the epoxy-amine polymers by curing epoxidian oligomers with aliphatic amines without additional heat input. The pathways are the oligomer-oligomeric modification of epoxy resins-epoxy oligomers (EO), with their conversion to oligoethercyclocarbonates (OECC) by carbonization with carbon dioxide. The cocuring of these oligomers as a result of aminolysis competing reactions is “epoxide-amine” (forming a network polymer) and “cyclocarbonate-amine” (forming the linear hydroxyurethane, extending the internodal chains). Formation of internal and intermolecular hydrogen bonds was established on hydroxycarbonates (HA) and linear polyhydroxyurethanes (PHU) model compounds by IR and NMR spectroscopy. The results of the hydrogen bond system formation processes explain the change in the relaxation and physicomechanical properties of hard polymers modified by the epoxy-amine compositions (OECC), containing aromatic and aliphatic links. This paper presents a possible OECC modificator, the optimal EO:OECC ratio and its influence on the cross-link frequency, the polarity, the fragment and chain flexibilities and, as a consequence, the possible stiffness regulation for selected epoxy polymers. Thus, the causes of the increase in deformation-strength and adhesion characteristics were established by a factor of 1.5 to 3.0 due to an increase in cohesive strength (as a result of the combined network operation with covalent and physical bonds), as well as reduction of residual stresses (by adding the aliphatic fragments as additional relaxants), and reducing the defectiveness of the boundary layers (polymer-substrate).

Assessment of commercial polymers with and without reactive groups using amino acid derivative reactivity assay based on both molar concentration approach and gravimetric approach

“…In general, owing to steric and induced effects, internal glycidyl groups are less reactive than end glycidyl groups (Mora et al, 2020). Furthermore, if a portion of the glycidyl group is hydrolyzed to form a hydroxyl group (OH group), an intramolecular hydrogen bond is likely to be formed between the glycidyl and OH groups (Stroganov et al, 2018).…”

“…In general, owing to steric and induced effects, internal glycidyl groups are less reactive than end glycidyl groups (Mora et al, 2020). Furthermore, if a portion of the glycidyl group is hydrolyzed to form a hydroxyl group (OH group), an intramolecular hydrogen bond is likely to be formed between the glycidyl and OH groups (Stroganov et al, 2018). This effect may make it easier for the glycidyl group to assemble inside the polymer molecule, making it less susceptible to attack by external chemicals (i.e., reducing the reactivity of the glycidyl group).…”

Hybrid polyhydroxyurethanes: How to overcome limitations and reach cutting edge properties?

“…Stroganov et al detailed the modification of epoxy-amine networks with cyclic carbonates to solve fragility and hardness problems. [105] Cyclic carbonates as additional fragments affected the molecular mobility and the relaxation properties. The elastic deformation was therefore enhanced.…”

Dynamic Mechanical and Chemorheology Analysis for the Blended Epoxy System with Polyurethane Modified Resin

“…Secondly, dispersed phases such as rigid particles, liquid crystal polymers, coreshell polymers and inorganic nanomaterials are added to the epoxy resin matrix to increase toughness [19][20][21]. Thirdly, curing agents with "flexible chain segment" in the molecular chain are rationally applied to introduce some flexible chain segment into the crosslinking network [22]. Thus, some thermosetting resins are penetrated into the epoxy resin network to form interpenetrating and semipenetrating network structure [23].…”