Novel Thermally-Reversible Epoxy-Urethane Networks

Abstract

Thermally-reversible epoxy-urethane networks are prepared by the reaction of diamines and diepoxy monomers containing two Diels-Alder adducts. The diepoxy compounds are formed via a Diels-Alder reaction between two epoxy-containing furans and bismaleimides having urethane moieties. The urethanebismaleimides were obtained by the reaction of 4-maleimidophenylisocyanate with poly(tetrahydrofuran) diols with M n = 650, 1000 and 1450. The epoxy-urethane networks display two glass transition temperatures in the range of −70 and −50 • C for the soft segment and 81-84 • C for the hard segment. At temperatures exceeding 116 • C the retro Diels-Alder reaction occurs, which leads to a significant loss in modulus.

Thermally reversible cross-linked poly(ether-urethane)s

“…4,4!-Dibenzyldiisocyanate (DBDI) (Savinesti, Romania) was purified before use by recrystallization from anhydrous cyclohexane (mp = 89-90°C), 4,4!-bismaleimido-diphenylmethane (A) was synthesized from 4,4!-diaminodiphenylmethane and maleic anhydride in a two-step method described in the literature [43] and recrystallized from toluene (mp = 158-159°C). The oligoether urethane bismaleimide (B) was synthesized from Terathane-650 and 4-maleimidophenyl isocyanate by the method described in the literature [41].…”

“…Our approach to removable polymer networks is the introduction of chemically labile linkages within cross-linked polymeric networks. We have explored the DA cycloaddition reactions between bismaleimide and furyl monomers or polymers [39][40][41][42]. The mechanical measurements showed a greater elongation at break for obtained polyurethane networks, elongation which can be even nine times higher than that of previously obtained polyurethane networks by Diels-Alder reaction [41].…”

Facile synthesis of environmental friendly halogen-free microporous terpolymer from renewable source with enhanced physical properties

“…The experimental data at 10°C min obtained by FWO method (Table 2) were substituted into Equation (9). Figure 8 shows the Z(α) À α master and experimental curve of the terpolymer VFUMA.…”

“…Furan resins have been made using phenol or formaldehyde by aldehyde condensation in the presence of an acid or alkali [5,6]. Furfural-based resins are an important class of thermosets that have been widely used as high-performance materials in diverse applications such as high toughness and self-repairing ability, adhesives, matrices for fiberreinforced composites, surface coatings, remendable polyurethane, and for electronic encapsulation [7][8][9][10][11][12][13][14][15].…”

Polyurethanes based on thermoreversible networks designed by Diels-Alder reaction

“…Due to its reversibility the DA reaction also represents a choice to create self-healing properties for polymer networks [18]. Concerning polyurethane, the DA reaction was employed in thermally remendable linear polymers [19][20][21][22] and thermally reversible networks [23][24][25][26][27]. The latter were designed in three different ways: i) by polymerization reaction of monomers containing maleimide-furan cycloadduct [26,28], ii) by crosslinking of linear polyurethane containing furan or maleimide pendant groups [27,29,30] and iii) by cycloaddition DA reaction between polyurethane containing furan end groups and multimaleimide monomers [19,[23][24][25][31][32][33].…”