Poly(methyl　methacrylate)-grafted　carbon　nanotubes　(PMMA@MWCNTs)　are　nondestructively　prepared　via　the　integration　of　mussel-inspired　polydopamine　(PDA)　chemistry　and　the　surface-initiated　atom　transfer　radical　polymerization　(ATRP)　method.　The　structures　and　properties　of　the　poly(vinylidene　fluoride)-based　(PVDF-based)　nanocomposites　filled　with　pristine　MWCNTs　and　PMMA@MWCNTs　are　investigated.　The　results　show　that　the　encapsulation　of　PMMA　on　the　MWCNTs　surface　not　only　improves　the　dispersibility　of　MWCNTs　in　the　PVDF　matrix　but　also　enhances　the　interfacial　interaction　between　MWCNTs　and　PVDF.　The　addition　of　PMMA@MWCNTs　nanofillers　to　PVDF　can　effectively　induce　the　crystal　structure　of　PVDF　to　transform　from　the　α-phase　to　the　β/γ　-phase,　and　nearly　100%　β/γ　-phase　PVDF　formed　when　the　nanofiller　loading　is　higher　than　5　wt%.　Compared　with　the　MWCNTs/PVDF　composites,　the　PMMA@MWCNTs/PVDF　composites　exhibit　obvious　improvement　in　the　percolation　threshold　because　the　PMMA　shells　hinder　the　direct　contact　of　the　MWCNTs.　Moreover,　the　loss　tangent　of　the　PMMA@MWCNTs/PVDF　composites　is　effectively　suppressed　due　to　the　reduced　leakage　current　in　the　composites　and　the　enhanced　interfacial　strength　between　the　nanofiller　and　the　matrix.　©　2019　WILEY-VCH　Verlag　GmbH　&　Co.　KGaA,　Weinheim