Tuning the properties of segmented polyhydroxyurethanes via chain extender structure

Abstract

The influence of chain extender structure on the properties of segmented polyhydroxyurethane (PHU) was investigated with four diamine molecules: 1,4‐diaminobutane, isophorone diamine, methylene bis(cyclohexyl amine), and bis(aminomethyl) norbornane. These nonisocyanate polyurethanes were synthesized with polytetramethylene oxide‐based soft segment and divinyl benzene dicyclocarbonate (DVBDCC) as hard segment. They were characterized with small‐angle X‐ray scattering (SAXS), dynamic mechanical analysis (DMA), and tensile testing. All PHUs possess nanophase‐separated morphology with interdomain spacings of 12 to 16 nm via SAXS. DMA shows that the nanophase separation is accompanied with broad interphases having a wide range of local compositions. These PHUs exhibit tan δ ≥ 0.30 over broad temperature ranges, indicating their potential as effective damping materials. The flow temperature (Tflow), the temperature range with tan δ ≥ 0.30, and the tensile properties of these PHUs are strongly affected by the molecular structure of the chain extender used in synthesis. At 50 wt % hard‐segment content, values of Tflow, tensile strength, and elongation‐at‐break can be tuned via chain extender from 57 to 105 °C, 1.6 to 22.4 MPa, and 70 to 500%, respectively. Notably, PHU at 50 wt % hard‐segment content, synthesized with norbornane‐based chain extender exhibits the best thermal and mechanical properties with Tflow of 105 °C, tensile strength of 22.4 MPa, elongation‐at‐break of 500%, and tan δ ≥ 0.30 over 74 °C in breadth. By varying hard‐segment content between 30 and 50 wt %, norbornane‐based PHUs afford broad tunability in tensile strength from 0.5 to 22.4 MPa with tan δ ≥ 0.30 spanning temperature range as large as 85 °C. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44942.

Green and sustainable polyurethanes for advanced applications

“…Further understanding into the molar mass limitation of polyhydroxyurethanes from side reactions and hydrogen bonding is addressed by Caillol et al . The mechanical properties of the polyhydroxyurethanes are shown to be tuned according to the incorporation of chain extender structures as reported by Torkelson et al . Similarly, Ditchel et al .…”

Design of hybrid nonisocyanate polyurethane coatings for advanced ambient temperature curing applications

“…Another promising route that has attracted great deal of interest is synthesis of NIPUs from addition polymerization of multifunctional cyclic carbonates with primary diamines or polyamines . It should be noted that the cyclic carbonate/amine reaction results in the formation of segmented polyhydroxyurethane systems containing beta‐hydroxy urethane . While additional intermolecular hydrogen bonds provide improved chemical resistance and thermal stability compared to conventional polyurethanes, mechanical properties of such NIPU coatings have been reported to be inferior.…”

“…[10][11][12] It should be noted that the cyclic carbonate/ amine reaction results in the formation of segmented polyhydroxyurethane systems containing beta-hydroxy urethane. [13][14][15] While additional intermolecular hydrogen bonds provide improved chemical resistance and thermal stability compared to conventional polyurethanes, mechanical properties of such NIPU coatings have been reported to be inferior. In addition, cyclic carbonates only react with primary amines while epoxy groups can react with both primary and secondary amines.…”

Thermoplastic polyurethane–urea elastomers with superior mechanical and thermal properties prepared from alicyclic diisocyanate and diamine

“…[1,2] Because a variety of long-chain diols, short-chain diols or diamines, and diisocyanates are available, a wide range of TPU elastomers can be produced to meet the needs of specific applications. The majority of such work has focused on improving the properties of TPU elastomers through variation or combination of the soft segments, [3][4][5][6][7] hard segments, [8][9][10][11] chain extenders, [12][13][14][15][16] and diisocyanates, [17][18][19] so as to make high-performance TPU elastomers. Non-isocyanate polyurethane thermoplastic elastomers has also appeared.…”

“…The tensile strength of common high-performance TPU elastomers is generally in the range of 10 to 40 MPa. [7,10,[12][13][14][15][16][17][18][19] Reports on TPU elastomers whose maximum tensile strength under nondeformed state [11] reached 50 to 60 MPa were rare. [14,[22][23][24] Naturally, these TPU elastomers may be called, arbitrarily of course, TPU elastomers with superhigh tensile strength.…”