Combination of polymerization and polycondensation in the synthesis, chemical modification, and cure of rolivsan thermosetting resins

Abstract

Rolivsan thermosetting resins (ROLs) attract constant attention due to their epoxy-like high processability; at the same time, their high-temperature performance is much better than that of epoxy resins and bismaleimides. Development of these materials involves a nontrivial approach to synthesis of thermostable resins; this approach is based on introducing a new structure-forming tool, that is, 1-arylethanol group. The present article demonstrates the important role of polycondensation in rolivsan chemistry. ROLs consist of (di)vinylaromatic ethers and thermosensitive monomeric and oligomeric (di)methacrylates, which are formed after a series of acid-catalyzed reactions between di-secondary aliphatic-aromatic diols, such as bis-[4-( α-hydroxyethyl)phenyl] ether, and unsaturated carboxylic acids, such as methacrylic acid. The process of ROL cure is a combination of polymerization and polycondensation. In the course of this process, in the temperature range from 140°С to 170°С, the initial densely cross-linked ROL-copolymer is formed as a result of three-dimensional radical copolymerization of highly unsaturated components. Post-cure of ROLs in the 200–300°С temperature interval leads to structural rearrangement (polycondensation). Cured ROLs demonstrate morphology typical of thermosets; they consist of highly cross-linked spherical microdomains that are weakly bound by less densely cross-linked polymer interlayers. Thermocatalytic transformations of rolivsans modified by small amounts of additives (epoxies and aromatic diamines) were used in the development of a new approach to synthesis of heat-resistant thermosetting resins via high-temperature polycondensation in interdomain layers (which are used as a peculiar kind of microreactors).

Thermal and thermomechanical properties of rolivsan unsaturated resins co‐cured with bisphenol A dicyanate

“…[6][7][8][9][10][11] ROLs are low-viscosity monomer/oligomer compositions formed during the acid-catalyzed reaction between bis-[4-(1-hydroxyethyl)-phenyl] ether and methacrylic acid (MAA). They consist of aromatic ethers with styrene-like and methacrylate end groups [6][7][8][9][10][11][12][13][14][15][16][17][18] (Scheme 1).…”

“…20 ROLs find applications as thermostable non-porous impregnating compounds (clear castings), sealing compounds, vacuum-dense glues, protective coatings, and binders for composites. 6,[9][10][11][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] The following polyfunctional compounds were studied as target additives (admixtures inactive in TFRP): epoxy resins, 10,11,[37][38][39][40][41][42][43] aromatic diamines, [44][45][46][47] aromatic tetra-amines and dianhydrides of aromatic tetracarbon acids. 48 Chemical modification with these compounds improved thermal, strength and adhesive properties of the cured ROLs.…”

“…6,[9][10][11][12] Rearrangement of the primary network structure caused by thermocatalytic transformation of thermosensible methacrylate bridges is reflected in the splitting of the band attributed to methacrylate group -О-С = O at 1715 cm À1 into a number of carbonyl bands at 1800, 1760, 1700, and 1670 cm À1 (anhydride, carboxylic, keto groups (Figure 6). 6,[9][10][11][12]19,23,25 )…”

Studies of Formation Mechanism, Structure, and Properties of Network Copolymers Obtained by Cocuring of Rolivsan Thermosetting Resins with Aromatic Diamines

“…Rolivsan thermosetting resins (ROLs) are a new class of unsaturated thermosetting resins featuring high glass-transition temperatures (T g ), excellent processability, low relative permittivity and mechanical losses, low moisture absorption, good mechanical properties, and satisfactory compatibility with various substrates [1][2][3]. They are obtained via acidcatalyzed reactions between disecondary aliphatic-aromatic diol (bis-(4-(α-hydroxyethyl)phenyl) ether) (BHEPE) and methacrylic acid (MAA) [1].…”

“…Thus, we propose to use certain implications of mechanism of the network formation as a new structure-forming tool for chemical modification of thermosets. The method has turned out to be effective in improving physicomechanical, thermal, and other useful properties of thermosets, as was illustrated by the example of thermochemical transformations of ROLs in binary systems containing epoxy resins [2,3,5] and aromatic di-and tetraamines [3,[5][6][7].…”