A simple one-pot non-isocyanate route for synthesizing thermoplastic polyureas is presented. In situ urethanization was conducted from the ring-opening reaction of ethylene carbonate with poly(propylene glycol) bis(2-aminopropyl ether) and hexanediamine,m-xylylenediamine, or diethylene glycol bis(3-aminopropyl) ether at 100 °C for 6 h under normal pressure. Melt transurethane polycondensation was successively conducted at 170 °C under a reduced pressure of 399 Pa for different time periods. A series of nonisocyanate thermoplastic polyureas(NI-TPUreas) were prepared. The NI-TPUreas were characterized by gel permeation chromatography,FTIR, 1 H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray diffraction, atomic force microscopy,and tensile test. NI-TPUreas exhibited Mn of up to 1.67 × 104 g/mol, initial decomposition temperature over 290 °C, and tensile strength of up to 32 MPa. Several crystallizable NI-TPUreas exhibited Tm exceeding 98 °C. NI-TPUreas with good thermal and mechanical properties were prepared through a green and simple one-pot non-isocyanate route.
A series of polyesteramide prepolymers[PrePEA（0/4,8）s] having mixed alternating bisesterdiamide units was synthesized via melt polycondensation from N,N＇-bis（2-hydroxyethyl）oxamide（0） and N,N＇-bis（2-hydroxyethyl）-adipamide（4） with sebacic acid（8） at different molar ratios.Chain extension of them was conducted with 2,2＇-（1,4-phenylene）-bis（2-oxazoline） and adipoyl biscaprolactamate as combined chain extenders.The chain extended polyesteramides[ExtPEA（0/4,8）s] were characterized by proton nuclear magnetic resonance（1H NMR）,gel permeation chromatography（GPC）,differential scanning calorimetry（DSC）,thermogravimetry analysis（TGA）,wide angle X-ray scattering,tensile test and enzymatic degradation.The results show that ExtPEA（0/4,8）s were crystalline polyesteramides.They had Tm up to 136.5 ℃ and initial decomposition temperature above 297.5 ℃.They crystallized in similar crystallites into Nylon-66 and degraded under the catalysis of protease or lipase.They are thermoplastic materials with tensile strength up to 21.5 MPa and elongation at break above 64.0％.
SUN Huiyun YIN Tiao LI Yue ZHAO Jingbo ZHANG Zhiyuan ZHANG Junying
Two kinds of aliphatic alternating polyesteramide prepolymers were prepared through melt polycondensation from N,N＇-bis（2-hydroxyethyl）-adipamide and adipic acid or sebacic acid. Chain extension of them was conducted with 2,2＇-（1,4- phenylene）-bis（2-oxazoline） and adipoyl biscaprolactamate as combined chain extenders. The chain extended polyesteramides （ExtPEAs） were characterized by IR, 1H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide angle X-ray scattering, tensile test and enzymatic degradation. The results showed that the ExtPEA（4,m）s were mainly constituted with the diester adipamide alternating units. ExtPEA（4,4） and ExtPEA（4,8） had Tm of 83.8℃ and 85.8℃ and initial decomposition temperature above 310.0℃. They crystallized similarly as Nylon-66 did and were flexible thermoplastic materials with tensile strength up to 25.64 MPa and strain at break up to 737%.
Cross-linked polyamides(c PAs)were prepared through direct bulk Michael addition and subsequent polycondensation.Several mixed hexanediamine multi-esters(HDAMEs)were generated through the Michael addition of 1,6-hexanediamine(HDA)and methyl acrylate(MA)at50℃ with different HDA/MA molar ratios.Melt polycondensation of HDAMEs then proceeded at 150 or 170℃ in flasks to obtain viscous fluids,and curing was continued in tetrafluoroethylene molds to obtain c PA films.The Michael addition was monitored on the basis of FTIR and ESI-MS spectra.The c PA films were characterized by DSC,TGA,dynamic mechanical analysis,and tensile test.These directly prepared c PAs exhibited Tg of 1–39℃,tensile strength of up to 45 MPa,and strain at break from 18%to 40%.The c PAs with high tensile strength and good toughness were successfully synthesized through the direct bulk Michael addition from HDA and MA followed with polycondensation.
