Relationship between microstructure and dielectric property of hydroxyl-terminated butadiene–acrylonitrile copolymer-based polyurethanes

Optimization of mechanical and dielectric properties of poly(urethane–urea)-based dielectric elastomers via the control of microstructure

“…For example, more recently, we demonstrated that the polyurethane elastomers with high dielectric constant (>7.6 at 1 kHz) and lower dielectric loss (<0.077 at 1 kHz) can be achieved using hydroxyl-terminated butadiene-acrylonitrile copolymer (HTBN) as so segment. 17 And, we found that the dielectric constant and breakdown strength of PUEs are strongly dependent on their hard domain structure and morphology. 18 In contrast with PUEs, the PUUEs have both urethane and urea units in their hard segments.…”

Hydrolysis‐resistant polyurethane elastomers synthesized from hydrophobic bio‐based polyfarnesene diol

“…Moreover, the unique "bottle brushes" structure of PFD makes PUEs exhibit a lower T g, SS than that of most HTPB-based PUEs with similar HS composition and HSC. 35,39 As shown in Figure 4 and Table III, △H MMT and △H M increased with the increasing of HSC. This indicated that the increase of average HS length favors the formation of mixed phase and well-ordered HS phase.…”

“…Prominent extent of phase separation might be the main reason that causes virtually constant values of T g , SS and T g , HS . Moreover, the unique “bottle brushes” structure of PFD makes PUEs exhibit a lower T g , SS than that of most HTPB‐based PUEs with similar HS composition and HSC . As shown in Figure and Table , ▵ H MMT and ▵ H M increased with the increasing of HSC.…”

“…Similar results have been reported by Saiani et al ., where they studied the origin of multiple melting endotherms in linear PUs, which contained MDI and 2‐methyl‐1,3‐propanediol (MPD) as HSs and polypropylene oxide end‐capped with ethylene oxide as soft segments . The observation of two different glass‐transition temperatures ( T g ), namely, T g of soft segments ( T g , SS ) and HSs ( T g , HS ), which are about −66 and 61 °C, respectively, indicates that the soft and hard phase are immiscible . The detailed thermal transition values of PUEs, including T g , SS , T g , HS , T M , T MMT , melting enthalpy (▵ H M ), and mixing enthalpy (▵ H MMT ), are summarized in Table .…”

“…[30][31][32] The observation of two different glass-transition temperatures (T g ), namely, T g of soft segments (T g, SS ) and HSs (T g, HS ), which are about −66 and 61 C, respectively, indicates that the soft and hard phase are immiscible. 35 The detailed thermal transition values of PUEs, including T g, SS , T g, HS , T M , T MMT , melting enthalpy (△H M ), and mixing enthalpy (△H MMT ), are summarized in Table III.…”