Molecular Design And Application Of Reactive Compatibilizers With High Compatibilization Efficiency

Double comb-like copolymers usually exhibits high compatibilization efficiency due to its symmetrical structure of the two side chains,which can easily balance and stabilize the interface of immiscible polymer blends,reduce the interfacial tension,and suppress the convergence of dispersed phases.It should be noted that the molecular structure(especially main/side chain structure)of the compatibilizer plays a decisive role on the compatibilization efficiency.In order to study its influence,three reactive comb copolymers containing different main/side chains were synthesized and their structural effects on compatibilizing effect were studied.Moreover,the type the reactive groups along compatibilizer is also an important role.A novel double-reactive compatibilization strategy is proposed in the paper for the first time.A dual-reactive compatibilizer was synthesized.It could graft the two-phase polymers via double chemical reactions during melt mixing,in-situ forming the"double comb-like"copolymers,thus improving the compatibility between the two phases.The paper includes the following four aspects:(1)Synthesis of reactive comb copolymers with different main/side chains:PMMA-COOH(M_n=4000)and P(MMA-co-BA)-COOH(M_n=4100)were synthesized via radical copolymerization.Then macromers(MMA macromer and MMA-co-BA macromer)with terminated C=C were prepared by nucleophilic open-ring addition reaction between carboxyl group and epoxy group in alkaline environment.Finally,three kinds of tooth copolymers(MG-MMA,SG-MMA and SG-BMA)with different main/side chains were obtained by initiating the copolymerizations of macromer,GMA and MMA or St via the“Grafting through”method.(2)Effect of main/side chain structure of compatibilizer on immiscible polymer blends:MG-MMA,SG-MMA and SG-BMA were applied to compatibilize PVDF/PLLA immiscible blends.It was shown that the all compatibilizers own high compatibilization efficiency but differ in the morphologies.The PMMA main chain of MG-MMA is likely to be bend owing to the affinity with PVDF phase,and thus forming curved interface and sea-island structure.However,the PS main chain of SG-MMA is extremely incompatible with the two phases.Its two side chains exert opposite forces on it,and thus easily being straight.Then the straight conformation helps to induce the interface with smaller curvature and co-continuous structure.Compared with the PMMA side chain of SG-MMA,the P(MMA-co-BA)side chain of SG-BMA is more flexible and can be fully immersed in the PVDF phase,making the main chain easier to be straight,and thus easier to obtain flat interface and co-continuous structure.(3)Synthesis of dual-reactive compatibilizers:A series of ternary copolymers SGM with different compositions were synthesized by radical copolymerization.AIBN is used as initiator to initiate the copolymerization of St,MAH and GMA in toluene.All products have been characterized and confirmed by FT-IR,TGA and NMR measurements.(4)Compatibilization effect of dual-reactive compatibilizer on immiscible polymer blends:The synthesized dual-reactive compatibilizers were applied in compatibilizing PA11/PLLA immiscible blends.It was shown that the dual-reactive compatibilizer SGM exhibits higher emulsifying efficiency than common compatibilizers with only one functional group.Moreover,it was found that the P(S93-G5-M2)is the optimized compatibilizer for PA11/PLLA system.The tensile strength and impact strength of the compatibilized blend are 59.9 MPa and 47.1 k J/m~2 respectively,totally achieving the balance between strength and toughness.