Modulation Of Nanostructures And Properties Of Epoxy Thermosets With Amphiphilic Block Copolymers

A series of amphiphilic block copolymers such as AB diblock,ABA triblock,star shaped and H shaped copolymers were synthesized via the combination of ring-open polymerization,reversible addition-fragmentation chain transfer polymerization?RAFT?,reversible addition-fragmentation chain transfer/macromolecular design via the interchange of xanthate?RAFT/MADIX?,atom transfer radical polymerization?ATRP?and click chemistry reaction.These block copolymers were used to modulate ordered and/or disordered nanostructures in thermosets.The nanostructures and formation mechanisms of the thermosets containing block copolymers were characterized.Furthermore,the properties of the nanostructured materials were investigated.The main results were summarized as follows:1.We investigated the evolution of reaction-induced microphase.Poly??-caprolactone?-block-polystyrene PCL-b-PS block copolymers was synthesized via ROP and ATRP polymerization.We found that the block copolymers in epoxy thermosets displayed reaction-induced microphase separation by spinodal decomposition?SD?,and the process of the separation was studied by use of small-angle X-ray scattering?SAXS?.A three-stage model of the microphase separation was discussed.2.Poly??-caprolactone?-block-?polystyrene?₂ PCL-b-?PS?₂ star shaped copolymer,polystyrene-block-[poly??-caprolactone?]₂PS-b-?PCL?₂starshapedcopolymer,?polystyrene?₂-block-poly??-caprolactone?-block-?polystyrene?₂?PS?₂-b-PCL-b-?PS?₂ H shaped copolymerand[poly??-caprolactone?]₂-block-polystyrene-block-[poly??-caprolactone?]₂?PCL?₂-b-PS-b-?PCL?₂ H shaped copolymer were successfully synthesized via the combination of ROP)and ATRP polymerization.All of them were incorporated into epoxy resin to obtain structured epoxy resins.It was found that the nanophases in the thermosets containing Y shaped copolymer and/or H shaped copolymer could be controlled by the topologies of block copolymer with same molecular weight and composition.3.poly?N-vinyl pyrrolidone?-block-poly?N-vinyl carbazole?-block-poly?N-vinyl pyrrolidone??PVPy-b-PVK-b-PVPy?triblock copolymer was synthesized successfully via sequential RAFT/MADIX process.The kinetic results showed that the polymerization was a living and controlled manner.In aqueous solutions,all these triblock copolymers self-assembled into the spherical micelles.We explored to measure the critical micelle concentrations of the triblock copolymers in aqueous solutions without externally adding fluorescence probe.It was found that reaction-induced microphase separation occurred in the mixtures of this triblock copolymer with epoxy.The nanostructured epoxy thermosets were capable of displaying fluorescent properties and the enhanced dielectric constants.4.The poly?ethylene oxide?-b-poly?N-vinyl carbazole??PEO-b-PVK?diblock copolymer was synthesized via RAFT/MADIX polymerization.The poly?ethylene oxide?-fullerene(PEO-C₆₀)was synthesized.The PEO-b-PVK diblock copolymer(and PEO-C₆₀)was incorporated into epoxy to prepare the thermosets.The spherical and wormlike nanostructured epoxy resins were successfully prepared vis a reaction-induced microphase separation mechanism.It was found that the formation of the nanostructures was in a reaction-induced microphase separation.All the samples display fluorescent properties and the enhanced dielectric constants.But the dielectric permittivity???decreased with increasing the content of PEO-C₆₀.5.The poly??-caprolactone?-b-poly?isoprene??PCL-b-PIP?diblock copolymer was synthesized via RAFT polymerization.The PCL-b-PIP diblock copolymer was incorporated into epoxy to prepare the thermosets.The spherical and vesicular nanostructured epoxy resins were successfully prepared.It was found that the formation of the nanostructures was in a self-assemble manner.The dielectric permittivity???increased,and then decreased with increasing the content of the diblock copolymer.