Pendant propargyloxy-functionalized aromatic (co)polycarbonates: synthesis, thermal crosslinking and chemical modification

Abstract

A bisphenol monomer bearing pendant propargyloxy group viz, 1, 1-bis (4-hydoxyphenyl)-1-(4′-propargyloxyphenyl) ethane (BPP) was synthesized starting from commercially available 1, 1, 1-tris (4-hydroxyphenyl) ethane (THPE) by mono O-propargylation reaction using propargyl bromide. A new series of pendant propargyloxy-functionalized aromatic (co)polycarbonates was synthesized by low-temperature solution polycondensation of BPP or different molar ratios of BPP and bisphenol-A with triphosgene in dichloromethane in the presence of triethylamine. The formation of reasonably high molecular weight (co)polycarbonates was confirmed by inherent viscosity (0.52–0.83 dL/g) and gel permeation chromatography (M_n 37,000–69,800 g/mol, polystyrene standards) measurements. ¹³C NMR spectral studies supported formation of random copolycarbonates in copolymerization of BPP and BPA with triphosgene. The 10% weight loss temperature (T₁₀) values of (co)polycarbonates, determined by thermogravimetric analysis under nitrogen atmosphere, were in the range 427–438 °C indicating their good thermal stability. The glass transition temperature (T_g) values of (co)polycarbonates were observed in the range 147–152 °C. The crosslinking ability of (co)polycarbonates involving pendant propargyloxy groups leading to formation of networked structure was evaluated via non-isothermal curing studies by DSC. As a proof-of-concept, the post-modification of a representative polycarbonate bearing pendant propargyloxy groups with 1-octane thiol as a model compound via thiol-yne click reaction was briefly studied.

Graphical abstract

Keywords:

• Aromatic polycarbonate
• propargyloxy groups
• thermal crosslinking
• thiol-yne click reaction
• chemical modification

Additional information

Funding

Samadhan S. Nagane and Deepak M. Maher are grateful to the Council of Scientific and Industrial Research (CSIR), New Delhi, India for fellowship. Prakash P. Wadgaonkar acknowledges CSIR for research grant under Emeritus Scientist Scheme (21(1075)/19/EMR-II).