RESUMO
In the present work, poly(methyl methacrylate) (PMMA) is successfully grafted onto poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) side chains via directly activated CF bonds using Cu(0)/2,2'-bipyridine as catalyst. The reaction mechanism and the initiating sites can be confirmed by the structure of the graft copolymer. The graft copolymerization exhibits first-order kinetics, and reaction conditions can affect the chemical composition of the graft copolymer, including reaction time, reaction temperature, solvents, the amount of catalyst, and monomer. The introduction of rigid PMMA side chains onto P(VDF-TrFE) can effectively tune the displacement-electric field hysteresis behaviors of P(VDF-TrFE) from normal ferroelectric to anti-ferroelectric, even linear-like dielectric, under high electric field, resulting in dramatically reduced energy loss while maintaining the discharged energy density. This work may provide an effective strategy to introduce functional groups into P(VDF-TrFE) copolymer via activation of CF bonds.
Assuntos
Polimetil Metacrilato/química , Polivinil/química , Catálise , Cinética , PolimerizaçãoRESUMO
In recent years, the interaction between HLA class I alleles and receptors of NK cells have been paid more attention in HLA-identical sibling hematopoietic stem cell transplantation (HLA-identical sibling HSCT). NK cells mediate alloreactions when the allogeneic targets do not express HLA class I alleles that block inhibitory receptors of NK cells. Alloreactive donor-derived NK cells reduce GVHD by eliminating host-type antigen-presenting cells, but favor engraftment by killing host lymphocyte cells and reduce the risk of relapse by eradicating leukemia cells. Moreover, activating receptors also influence the outcome of HLA-identical sibling HSCT. In this review, the advance of the impact of both inhibitory and activating KIR (killer cell immunoglobulin-like receptor, KIR) on the outcome of HLA-identical sibling HSCT is briefly summarized.