Activation and transformation of CO_2 is one of the important issues in the field of green and sustainable chemistry. Herein, CO_2 as a carbonoxygen resource was converted to CO_2-polyurea with 1,6-hexanediamine throu...Activation and transformation of CO_2 is one of the important issues in the field of green and sustainable chemistry. Herein, CO_2 as a carbonoxygen resource was converted to CO_2-polyurea with 1,6-hexanediamine through a two-step polymerization. The reaction parameters such as temperature, pressure and reaction time were examined; and several kinds of catalysts were screened in the absence and presence of NMP solvent. The formed oligomer and the final polyurea were characterized by FT-IR, VT-DRIFTS, NMR, XRD, AFM and their thermal properties were examined by TGA and DSC. It was confirmed that the final polyurea has a high thermal stability; the melting temperature is 269℃ and the decomposition temperature is above 300℃. It is a brittle polymer with a tensile strength of 18.35 MPa at break length of 1.64%. The polyurea has a stronger solvent resistance due to the ordered hydrogen bond in structure. The average molecular weight should be enhanced in the postpolymerization as the appearance, hydrogen bond intensity, crystallinity, melting point and the thermal stability changed largely compared to the oligomer. The present work provides a new kind of polyurea, it is expected to have a wide application in the field of polymer materials.展开更多
Carbon dioxide(CO_(2)) as a sustainable resource instead of toxic reagents has attracted considerable attention in synthesis of chemicals and polymeric materials.Herein,a kind of cyclic oligourea was synthesized via p...Carbon dioxide(CO_(2)) as a sustainable resource instead of toxic reagents has attracted considerable attention in synthesis of chemicals and polymeric materials.Herein,a kind of cyclic oligourea was synthesized via polycondensation of CO_(2) with 4,7,10-trioxa-1,13-tridecanediamine(TTD)followed by effective separation and purification processes.We developed an efficient separation strategy in which the linear oligourea molecules were selectively transformed to macromolecular polyurea molecules by a reaction of the–NH_(2) end group with 4,4’-diphenylmethane diisocyanate(MDI),followed by separation from cyclic oligourea using selected solvents.The structure and physicochemical properties were confirmed by MALDI-TOF mass spectra,NMR,Cryo-EM,thermal analysis and solubility measurement.The well-defined cyclic oligourea was produced with a high purity(99.4%)and the average-number molecular weight(Mn)of 1040 Da.It is semi-crystalline in structure with a melting point of 106℃and glass transition point of-10℃.The cyclic oligourea presented characteristically difference to its linear analogue.This work provides a new member to cyclic polymer family.展开更多
基金the financial support from National Basic Research Program of China(2016YFA0602900)National Natural Science Foundation of China(21672204,21273222)+1 种基金Youth Innovation Promotion Association CAS(2016206)Jilin Provincial Science and Technology Program of China(20160203007GX)
文摘Activation and transformation of CO_2 is one of the important issues in the field of green and sustainable chemistry. Herein, CO_2 as a carbonoxygen resource was converted to CO_2-polyurea with 1,6-hexanediamine through a two-step polymerization. The reaction parameters such as temperature, pressure and reaction time were examined; and several kinds of catalysts were screened in the absence and presence of NMP solvent. The formed oligomer and the final polyurea were characterized by FT-IR, VT-DRIFTS, NMR, XRD, AFM and their thermal properties were examined by TGA and DSC. It was confirmed that the final polyurea has a high thermal stability; the melting temperature is 269℃ and the decomposition temperature is above 300℃. It is a brittle polymer with a tensile strength of 18.35 MPa at break length of 1.64%. The polyurea has a stronger solvent resistance due to the ordered hydrogen bond in structure. The average molecular weight should be enhanced in the postpolymerization as the appearance, hydrogen bond intensity, crystallinity, melting point and the thermal stability changed largely compared to the oligomer. The present work provides a new kind of polyurea, it is expected to have a wide application in the field of polymer materials.
基金financial support from the National Key Research and Development Program of China(2016YFA0602900)the National Natural Science Foundation of China(NSFC 21672204)+1 种基金the Youth Innovation Promotion Association CAS(2016206)the Chinese Academy of Sciences President’s International Fellowship Initiative(2018VCA0012)。
文摘Carbon dioxide(CO_(2)) as a sustainable resource instead of toxic reagents has attracted considerable attention in synthesis of chemicals and polymeric materials.Herein,a kind of cyclic oligourea was synthesized via polycondensation of CO_(2) with 4,7,10-trioxa-1,13-tridecanediamine(TTD)followed by effective separation and purification processes.We developed an efficient separation strategy in which the linear oligourea molecules were selectively transformed to macromolecular polyurea molecules by a reaction of the–NH_(2) end group with 4,4’-diphenylmethane diisocyanate(MDI),followed by separation from cyclic oligourea using selected solvents.The structure and physicochemical properties were confirmed by MALDI-TOF mass spectra,NMR,Cryo-EM,thermal analysis and solubility measurement.The well-defined cyclic oligourea was produced with a high purity(99.4%)and the average-number molecular weight(Mn)of 1040 Da.It is semi-crystalline in structure with a melting point of 106℃and glass transition point of-10℃.The cyclic oligourea presented characteristically difference to its linear analogue.This work provides a new member to cyclic polymer family.
