Controlled Surface Modification On Jute Fibers Via The Combination Between HRP-initiated RAFT And Grafting

In recent years,enzymes achieve great success in applications in the fields from synthesis of polymers to graft modification of materials owing to its varied advantages including high efficiency,great specificity,moderate and environmental-friendly reaction.In our study,HRP/ACAC/H₂O₂ system was used to active free radicals and catalyzing the grafting of well-controlled polymers on the surface of lignin-based cellulose materials.Hence,enzymatic RAFT polymerizations of different monomers were firstly studied.Number-average molecular weight?Mn?and polydispersity?PDI?were detected by gel permeation chromatography?GPC?,and semilogarithmic kinetic plots were also researched to confirm whether the above-mentioned process was RAFT polymerization.In the presence of CTA,the low values of PDI were achieved,and the excellent linear evolution of Mn with time was also observed.What's more,excellent linear kinetics,as expected for the controlled RAFT polymerization,were observed for the semilogarithmic plot of monomer conversion vs polymerization time.Based on the above-mentioned experiments,C=C groups were firstly grafted on jute by the esterification between acryloyl chloride?AC?and hydroxyl groups,and then HRP/ACAC/H₂O₂ system was applied in the initiation of“graft from”RAFT polymerization on jute surface.Cellulose and lignin,as the main composition of jute,were used to simulate the grafting modification on jute.C=O groups corresponding to ester groups and Amide I groups belonged to poly acrylamide?PAM?chains were all recorded in FTIR spectra,preliminary proofing the feasibility of enzymatic controlled grafting.For the grafting of jute fibers,the values of C=C groups were detected by titration.Compared with that of lignin and cellulose,similar changes in FTIR spectra were observed.What's more,C content of AC-jute greatly increased and great amount of N content on PAM-jute surfaces was also detected by XPS and EDS tests.All the above-described results confirmed the successful enzymatic controlled grafting polymerization on jute surface.For better understanding the mechanism of HRP-initiated RAFT graft polymerization modification,graft ratios and AM conversions,were all determined in this study.Compared with traditional enzymatic polymerization,a great linear kinetic was observed in the semilogarithmic plot of AM conversion vs polymerization time in the HRP-initiated RAFT graft polymerization.The increase of graft ratio was also regular and linear in the presence of DDMAT,which was as expected for the controlled polymerization.In our experiments,the modification on jute surface via the method of the combination between HRP-initiated controlled RAFT polymerization and enzymatic radical coupling was further studied.Lignin,as the model compound of jute fibers,was firstly studied.In PAM-lignin FTIR spectrum,amide I group was observed;for PBA-lignin samples,C=O groups belonged to ester groups was also recorded in its FTIR spectrum.The Mn values of PAM-lignin and PBA-lignin were all obviously increased.These results confirmed the feasibility of enzymatic“graft to”controlled modification.For PAM modified and PBA grafted jute samples,the changes in surface elemental contents also proofed the enzymatic grafting on the surface of jute fibers.The changes in jute fibers after enzymatic RAFT“graft to”modification were also reflected by the transition of wetting behaviors on these surfaces:for PAM-jute,the surface became more hydrophilic,while after the grafting of PBA,the increase concentration of ester groups introduced the hydrophobicity for jute surface.