A Novel method of controlling the molecular weight of PAN-lignin copolymer—Synthesis and characterization

•The novel method of synthesis of PAN lignin copolymer so as to have a controlled polymerization reaction.•Polymerization is carried out without the modification of lignin.•Various characterization to ascertain the PAN lignin copolymer formation.•NMR studies to show the interlinkages between lignin and poalyacrylonitrile.•Cost effectiveness methods since the solution can be directly used for further wet spinning process to get the precursor fiber. Polyacrylonitrile-lignin copolymer (PLC) has been successfully prepared via solution polymerization technique by a three step synthesis procedure. The main aim of this research is to control the molecular weight of the PLC by varying the initiator, monomer or solvent concentration in the reaction. The loading of lignin was kept constant which is 20 wt % in the PLC. The Polyacrylonitrile (PAN) homopolymer synthesized in the first step and the final copolymer PLC were characterized by various techniques such as FTIR, NMR, DSC, UV etc. The chemical bonding of lignin with the PAN backbone has been ascertained by these characterisation methods. This study explores a promising way to control the molecular weight of PLC copolymer which can be further used in the production of precursor fibre for carbon fibre. [Display omitted]