02857nas a2200265 4500008004100000022001400041245013400055210006900189260000800258300001200266490000800278520193200286653002302218653002602241653002002267653002402287653002602311100002502337700001802362700000502380700002202385700003002407700002802437856012602465 2019 eng d a0014-305700aAromatic polyesters containing pendant azido groups: synthesis, characterization, chemical modification and thermal cross-linking0 aAromatic polyesters containing pendant azido groups synthesis ch cJUL a180-1890 v1163 a
A partially bio-based bisphenol containing pendant azido group viz., 4,4'-(5-azidopentane-2,2-diyl) diphenol (AZBPA) was synthesized starting from 4,4'-bis (4-hydroxyphenyl) pentanoic acid. AZBPA was reacted with isophthaloyl chloride (IPC), terephthaloyl chloride (TPC) and a mixture of IPC/TPC (50:50 mol%) by phase transfer-catalyzed interfacial polycondensation route to obtain aromatic polyesters containing pendant azido groups. Copolyesters containing pendant azido groups were also synthesized by polycondensation of different molar proportions of AZBPA and commercially available 4,4'-(1-phenylethane-1,1-diyl) diphenol (BPA-AP) with IPC. Inherent viscosities and number average molecular weights of (co)polyesters were in the range 0.85-1.64 dL/g and 58,900-190,400, respectively, indicating the formation of reasonably high molecular weight polymers. Tough, transparent, and flexible films could be cast from chloroform solutions of these polyesters. X-Ray diffraction analysis showed that (co)polyesters were amorphous in nature. (Co)polyesters were characterized using FT-IR, H-1 NMR spectroscopy, XRD, TGA and DSC analysis. The chemical modification of a representative copolyester containing pendant azido groups was carried out quantitatively using copper-catalyzed azide-alkyne cycloaddition (CuAAC) with two alkynes viz., phenyl acetylene (PA) and ethynyl-4-nitrobenzene (ENB). Additionally, (co)polyesters containing pendant azido groups were thermally cross-linked (170 degrees C/12 h) leading to the formation of network structures based on azide to nitrene decomposition and subsequent reactions on polyester backbone. The selected cross-linked polyesters were characterized by stress-strain measurements. The cross-linked polymers exhibited higher tensile strength and Young's modulus and lower % elongation at break compared to corresponding pristine polyesters containing pendant azido groups.
10aAromatic polyester10aChemical modification10aClick chemistry10aPendant azido group10aThermal cross-linking1 aNagane, Samadhan, S.1 aVerma, Savita1 a1 aSane, Prakash, S.1 aDhanmane, Sushilkumar, A.1 aWadgaonkar, Prakash, P. uhttp://library.ncl.res.in/content/aromatic-polyesters-containing-pendant-azido-groups-synthesis-characterization-chemical