Polyisobutylene‐based segmented polyureas. I. Synthesis of hydrolytically and oxidatively stable polyureas

Abstract

Novel segmented polyurea elastomers containing soft polyisobutylene (PIB) segments were synthesized and characterized. The key ingredient, primary amine‐telechelic PIB oligomers (NH2‐PIB‐NH2) with number average molecular weights of 2500 and 6200 g/mol were synthesized. PIB‐based polyureas were prepared by using various aliphatic diisocyanates and diamine chain extenders with hard segment contents between 9.5 and 46.5% by weight. All copolymers displayed microphase morphologies as determined by dynamic mechanical analysis. Tensile strengths of nonchain‐extended and chain‐extended polyureas showed a linear dependence on the urea hard segment content. PIB‐based polyureas prepared with NH2‐PIB‐NH2 of Mn = 2500 g/mol, 4,4′‐methylendbis(cyclohexylisocyantate), and 1,6‐diaminohexane containing 45% hard segment exhibited 19.5 MPa tensile strength which rose to 23 MPa upon annealing at 150 °C for 12 h. With increasing hard segment content, elongation at break decreased from ∼ 450% to a plateau of 110%. The hydrolytic and oxidative stability of PIB‐based polyureas were unprecedented. Although commercial “oxidatively resistant” thermoplastic polyurethanes degraded severely upon exposure to boiling water or concentrated nitric acid, the experimental polyureas survived without much degradation in properties. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 38–48, 2009

Multiscale Modeling of the Morphology and Properties of Segmented Silicone-Urea Copolymers

“…Highly non-polar oligomers, such as; polydimethylsiloxane, polybutadiene, polyisobutylene and poly(ethylene-butylene) are also used to obtain specific properties [5][6][7][8][9][10][11]. Hard segments mainly consist of urethane, urea, urethaneurea, amide, aramide, imide and aromatic ester groups [8][9][10][11][12][13][14][15]. Due to the presence of bidentate hydrogen bonding and their higher cohesive energy densities, segmented polyureas display better microphase separation and improved mechanical properties when compared with their polyurethane analogues [16,17].…”

Synthesis and Characterization of New Polyurea Elastomers by Sol/Gel Chemistry

“…[13,14] Generally, the reaction for obtaining linear polymers (thermoplastic block copolymers) takes place between a diisocyanate (aromatic or aliphatic) with an aminoterminated prepolymer or resin (generally aliphatic). [8,10,[14][15][16][17][18][19][20][21][22][23] The prepolymer or resins contains both soft segments with low glass transition temperatures and amorphous melts, and hard domains with high glass transition and high melting temperatures due to hydrogen bonding [24,25] as physical crosslinks. Little work has been done for the synthesis and study of polymer networks because of the fast reactivity during chemical crosslinking, except by using spray or reaction injection molding.…”

Morphology and Mechanical Properties of Thermoplastic Polyurethanes Containing Polyisobutylene/Poly(tetramethylene oxide) Mixed Segments

“…Especially, polyisobutylene (PIB) has been suggested as a very promising polymer to develop biostable TPUs, because it shows excellent biostability and biocompability. Recently, PIB-based TPUs (including the similar segmented polyureas and polyurethaneureas) have been successfully synthesized (7)(8)(9)(10)(11). As expected, PIB-based TPUs show significantly enhanced biostability (11,12), and their biocompatibility is also comparable to conventional TPUs based on polyether or polyester (13).…”

“…Recently, PIB-based TPUs (including the similar segmented polyureas and polyurethaneureas) have been successfully synthesized (7)(8)(9)(10)(11). As expected, PIB-based TPUs show significantly enhanced biostability (11,12), and their biocompatibility is also comparable to conventional TPUs based on polyether or polyester (13). However, these TPUs exhibited very poor mechanical strength, which limits their practical applications (7)(8)(9)14).…”