Multiphase polymer composites offer a versatile platform for constructing efficient 3D conductive networks by regulating filler distribution.However,controlling the spatial distribution and network formation of 2D fil...Multiphase polymer composites offer a versatile platform for constructing efficient 3D conductive networks by regulating filler distribution.However,controlling the spatial distribution and network formation of 2D fillers like boron nitride(BN)flakes in immiscible polymer blends remains a major challenge for achieving efficient thermal conductivity.This work introduces a strategy to regulate the cross-linking degree of low-density polyethylene(LDPE)in poly(L-lactic acid)(PLLA)/LDPE blends,enabling effective control over BN localization.BN flakes preferentially localize in the LDPE phase,forming double-percolated networks across broad blend compositions.Controlled LDPE cross-linking suppresses domain coalescence and promotes a secondary segregated BN network via capillary bridginginduced agglomeration.This manipulation of domain viscoelasticity enhances 3D filler network formation,increasing the maximum through-plane thermal conductivity of the polymer composites from 2.02 to 2.58 W m^(−1) K^(−1).Our findings offer a facile route for tailoring 3D filler networks in multiphase polymer composites for improved thermal conduction.展开更多
The electrical conductivity of conductive polymer composites(CPCs)with a classical double percolated structure is highly connected to the phase morphology.However,lots of conductive fillers,which are added to guarante...The electrical conductivity of conductive polymer composites(CPCs)with a classical double percolated structure is highly connected to the phase morphology.However,lots of conductive fillers,which are added to guarantee CPCs’electrical conductivity,caused increased viscosity and limited phase coarsening in traditional atmosphere annealing.Herein,a novel processing method of supercritical carbon dioxide(scCO_(2)),assisted phase coarsening for polylactide acid(PLA)/polystyrene(PS)/multi-wall carbon nanotube(MWCNT)composites was explored.It was first proved that obviously coarsened conductive network of double percolation after scCO_(2) annealing was achieved,which benefited from CO_(2) plasticized polymer chains and thus decreased viscosity.Therefore,the electrical properties and electromagnetic interference(EMI)shielding performance of the composites were significantly improved.The percolation threshold of PLA/PS/MWCNT composites decreased from 0.31 wt.%to 0.16 wt.%,and EMI shielding effectiveness increased from 32.8 to 37.4 dB at 5 wt.%MWCNT loading.This work provides a simple,green,and effective way of post-processing to tailor the phase structure via varying conditions of annealing medium such as temperature,CO_(2) pressure,and time,and gains CPCs with improved electrical conductivity and EMI shielding performance.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.U21A2092,52303079,and U22A20248)the Special Support Plan for High Level Talents in Zhejiang Province(2022R51008).
文摘Multiphase polymer composites offer a versatile platform for constructing efficient 3D conductive networks by regulating filler distribution.However,controlling the spatial distribution and network formation of 2D fillers like boron nitride(BN)flakes in immiscible polymer blends remains a major challenge for achieving efficient thermal conductivity.This work introduces a strategy to regulate the cross-linking degree of low-density polyethylene(LDPE)in poly(L-lactic acid)(PLLA)/LDPE blends,enabling effective control over BN localization.BN flakes preferentially localize in the LDPE phase,forming double-percolated networks across broad blend compositions.Controlled LDPE cross-linking suppresses domain coalescence and promotes a secondary segregated BN network via capillary bridginginduced agglomeration.This manipulation of domain viscoelasticity enhances 3D filler network formation,increasing the maximum through-plane thermal conductivity of the polymer composites from 2.02 to 2.58 W m^(−1) K^(−1).Our findings offer a facile route for tailoring 3D filler networks in multiphase polymer composites for improved thermal conduction.
基金The authors acknowledge the financial support of the National Natural Science Foundation of China(No.52173039).
文摘The electrical conductivity of conductive polymer composites(CPCs)with a classical double percolated structure is highly connected to the phase morphology.However,lots of conductive fillers,which are added to guarantee CPCs’electrical conductivity,caused increased viscosity and limited phase coarsening in traditional atmosphere annealing.Herein,a novel processing method of supercritical carbon dioxide(scCO_(2)),assisted phase coarsening for polylactide acid(PLA)/polystyrene(PS)/multi-wall carbon nanotube(MWCNT)composites was explored.It was first proved that obviously coarsened conductive network of double percolation after scCO_(2) annealing was achieved,which benefited from CO_(2) plasticized polymer chains and thus decreased viscosity.Therefore,the electrical properties and electromagnetic interference(EMI)shielding performance of the composites were significantly improved.The percolation threshold of PLA/PS/MWCNT composites decreased from 0.31 wt.%to 0.16 wt.%,and EMI shielding effectiveness increased from 32.8 to 37.4 dB at 5 wt.%MWCNT loading.This work provides a simple,green,and effective way of post-processing to tailor the phase structure via varying conditions of annealing medium such as temperature,CO_(2) pressure,and time,and gains CPCs with improved electrical conductivity and EMI shielding performance.
