Research On Preparation And Performance Of Functional Hyperbranched Polymeric Ionic Liquids Toughened Thermosettings

Hyperbranched polymers(HBPs)with highly branched structure have become an excellent way to modify thermosettings due to their enhancing and toughening effect on thermosetting.However,the multi-functionlization(reducing curing temperature,toughening,regulating and controlling phase structure)of hyperbranched polymers is still a challenge.Facing to this problem,a variety of hyperbranched polymeric ionic liquids were synthesized,the effects of hyperbranched polymeric ionic liquids on the properties of thermosettings were investigated in details:(1)The hyperbranched polymeric ionic liquids(HBPC-Mim-n,n=1,2 and 3)were synthesized with carboxyl-terminated hyperbranched polymers HBPC-n(n=1,2 and 3)and 1-methylimidazole(1-MI).The structures of HBPC-Mim-n were characterized by FTIR,1H-NMR and GPC.The effects of HBPC-Mim-n on curing behaviors,mechanical properties and thermal performances of epoxy resins were studied.Differential scanning calorimetry studies confirmed that the curing reaction was accelerated with the presence of HBPC-Mim-n.The mechanical and thermal properties of epoxy resins were improved with the addition of HBPC-Mim-n.Mechanical properties of epoxy resins increase to a critical value and then slightly decrease when further increasing the molecular weight and content of HBPC-Mim-n.The maximum mechanical performance of epoxy resins was achieved by incorporation of 9phr HBPC-Mim-2.The reinforcing and toughening mechanism of HBPC-Mim-n can be explained by an “in situ” reinforcing and toughening mechanism.(2)The hyperbranched polymeric ionic liquids with different microcosmic chemical structures(terminal group and molecular weight)were obtained via thiol-terminated hyperbranched polymers THBP-n(n=1,2 and 3)and allyl ionic liquids and the structures were confirmed by FTIR,1H-NMR and GPC.The effects of hyperbranched polymeric ionic liquids on the properties of benzoxazines were studied.The blending of hyperbranched polymeric ionic liquids with benzoxazines decreased the temperature for ring opening of the benzoxazines.The higher catalytic activity was achieved by the hyperbranched polymeric ionic liquid containing PF6-anion and AMIM+ cation.The mechanical properties of hybrid resins increase first and then decrease with increase molecular weight and content of hyperbranched polymeric ionic liquid.The mechanical performances of the benzoxazines reach a threshold value when added 3wt% HBP-AMIM+PF6--2.The phase structures of the benzoxazines were regulated through the alkyl chain lengths of hyperbranched polymeric ionic liquids.