Greenly Coating Carbon Nanotubes By Mn Coordinated Polyionic Liquid And Their High Performance Cyanate Ester Resin

Cyanate ester(CE)resin is known as a kind of most competitive heat-resistant thermosetting resin for manufacturing structure/function materials in the 21st century due to its outstanding heat resistance,low dielectric constant and loss over a wide range of frequencies and temperatures.High curing temperature and brittleness are common shortages of heat-resistant thermosetting resins.CE resin needs to be cured at high temperature(>250 ℃)for long time,and the symmetric triazine ring structure in cured CE resin leads to its brittleness.Therefore,it remains an urgent problem of how to reduce the curing temperature and improve the toughness while maintaining outstanding heat resistance and dielectric properties of CE resin.The thesis aims at solving above problems.First,specific to the curing characteristics of CE,an ionic liquid(IL-Mn)containing vinyl and amino groups while anion consisting of transition metal manganese was synthesized.In order to give full play to the toughening advantage of carbon nanotubes(CNTs),two kinds of multifunctional hybrids(CNT/PIL-Mn and CNT/HBPIL-Mn)were prepared by in situ polymerization on the surfaces of CNTs.There exists strong π-πinteraction between CNT and PIL-Mn,and the tubular structures of CNTs aren’t destroyed.Second,the catalytic behavior and mechanism of CNT/PIL-Mn on CE were studied systematically.CNT/PIL-Mn can catalyze CE effectively and there is a synergetic effect between CNT and PIL-Mn.The active hydrogen in CNT/PIL-Mn promotes the formation of Mn2+-π bond and the activation energy of CE curing is reduced.Then series of CNT/PIL-Mn/CE resins were prepared and their mechanical(toughness and rigidity),thermal(glass transition temperature and initial thermal decomposition temperature)and electrical(dielectric constant and loss)properties were systematacially discussed.The integrated performncs of CNT/CE and CE resins were also studied for comparison.Results show that all CNT/PIL-Mn/CE resins have better toughness,rigidity and heat resistance than CNT/CE and CE resins,while CNT/PIL-Mn/CE resin also maintains excellent dielectric properties as CE resin.Those differences prove that CNT/PIL-Mn is an effective catalyst and toughening agent of CE,this merit is attributed to the uniform distribution of CNTs in CE resin,and the unique structure of CNT/PIL-Mn has an effective catalytic effect on CE and improves the microstructure of CE resin.Third,CNT/HBPIL-Mn was added into CE to prepare resins with two different post curing procedures,and those post cured at 200 ℃ for 4 h or 220 ℃ for 4 h were coded as CNT/HBPIL-Mn(200)and CNT/HBPIL-Mn(220),respectively.The results show that only 0.5 wt%addition of CNT/HBPIL-Mn reduces the peak curing temperature of CE dramatically to 274.3 ℃,and all CNT/HBPIL-Mn/CE resins have better mechanical properties(toughness and rigidity),improved initial thermal decomposition temperature and lower dielectric constant than CE(240)and CNT/PIL-Mn/CE(220)resins.The differences of above performances originate from the improved microstructures of resin induced by the present of unique branched structure of hyperbranched polysiloxane.