Preparation And Properties Of Degradable Hyperbranched Polymers For Marine Anti-biofouling

Marine fouling refers to the undesirable attachment of various marine organisms on the underwater surface,and it greatly affects the service life of marine equipment and facilities.Recently,the mainstream and widely-used antifouling technologies have poor antifouling performance under static conditions,and their non-degradable main chains could accumulate in the marine environment,resulting in microplastic pollution.In this thesis,to aim at the above two problems,we have utilized various functional monomers and synthesis methods to prepare degradable hyperbranched polycaprolactone elastomer,hyperbranched antifouling polymer with degradable branching,hyperbranched antifouling polymer with degradable main chains and degradable hyperbranched polymer with“kill-resist”surface.The relationship between mechanical properties,antifouling properties and degradation of the materials and their chemical compositions and structures has been studied.The main contents are as follows:(1)Hyperbranched polycaprolactone(h-PCL)was synthesized by ring-opening polymerization of caprolactone,and grafted silane coupling agent to prepare a biodegradable elastomer.Quartz crystal microbalance with dissipation measurements(QCM-D)show that the elastomer can form dynamic surface attributed to the enzymatic degradation in PCL segments,and its degradation rate is able to be effective controlled by the branching degree and the content of PCL.The Water Contact Angle,Atomic Force Microscope and Nanoindentor tests show that the elastomer has a smoothness,low surface energy and elastic surface.Pseudobarnacle removal test proves that the elastomer has good fouling release performance.(2)Hyperbranched antifouling polymer with degradable branching was synthesized by vinyl-functional Econea,divinyl-functional poly(ε-caprolactone)and butyl methacrylate.As revealed by ~1H NMR,the vinyl conversion linearly increases over reaction time during polymerization,and the final conversion rate above 90%after 24 h.QCM-D and accelerated degradation tests show that the degradation rate and the molecular weight of polymer after degradation can be well regulated by the PCL content.Antifouling assays indicate that the coating has good antibacterial and anti-biofilm activities.(3)Hyperbranched poly(ester-co-vinyl)with degradable main chains was developed via radical ring-opening copolymerization(rROP)of 2-methylene-1,3-dioxepane(MDO),vinyl acetate(VAc)and diethylene glycol divinyl ether(DEGDVE).The reaction rate of MDO and DEGDVE is close,thus the cleavable ester bonds are randomly distributed in the main chain and can degrade into small fragments with molar masses of 400～600 g/mol,which is ecologically friendly.Such polymer with vinyl groups can form a crosslinked network by UV curing,and has good adhesion to epoxy panel.Mass loss test shows that the degradation rate can be well regulated with MDO content and the enzyme content,which proves that the coating is enzyme-responsive.The antifouling assays reveal that the coating exhibits remarkable antifouling performances and can effectively inhibit the adhesion of protein,marine bacteria and diatoms.(4)Vinyl 2-(ethoxycarbonothioylthio)acetate(ECTVA)and 2-(trimethoxysilyl)propyl dimethylaminopropionate(SiDMAP)was synthesized.By using the rROP of MDO,VAc,vinyl chloroacetate and ECTVA,the degradable hyperbranched polymer containing chlorine atoms was prepared.After the grafting of SiDMAP,the polymer becomes the cationic polymer whose side chains can hydrolyze and generate zwitterions.~1H NMR spectra shows that the reaction rate of MDO and VAc monomers is very close,so that the ester bond can be evenly incorporated into the main chain.Such polymer coating has good mechanical properties and adhesion strength.WCA and Fourier Transform Infrared Spectrometer tests reveal that the material can realize the transformation from cation to zwitterion through hydrolysis.The“kill-resist”functionalized surface of the material can regenerate itself by the degradation of main chains,and exhibits excellent antifouling abilities.