Silica aerogels(SAs)impart low density and excellent thermal insulation to polymer systems,yet incorporating hydrophobic SAs into aqueous rubber latex systems remains challenging owing to their poor dispersibility and...Silica aerogels(SAs)impart low density and excellent thermal insulation to polymer systems,yet incorporating hydrophobic SAs into aqueous rubber latex systems remains challenging owing to their poor dispersibility and potential to destabilize the latex.Although previous studies have dispersed SAs in aqueous poly(vinyl alcohol)(PVA),the stability of such dispersions and their effectiveness as bridging media for latex integration have not been thoroughly evaluated,which limits their practical application in latex compounding.This study systematically examined how the surface chemistry governs hydrolytic stability,interfacial behavior,and latex compatibility in PVA-assisted aqueous processing.Two hydrophobic SAs were prepared:ethoxy-modified SA(E-SA)and methyl-modified SA(M-SA).Both initially formed a homogeneous PVA slurry,but E-SA rapidly hydrolyzed its surface—OCH_(2)CH_(3)groups,releasing ethanol,becoming hydrophilic,and undergoing irreversible nanopore collapse.In contrast,M-SA maintains its structural integrity and hydrophobicity because its—Si(CH_(3))_(3)groups are highly resistant to hydrolysis.This divergence dictates the behavior during latex blending.The ethanol released from E-SA disrupts electrostatic and steric stabilization,inducing latex coagulation,whereas M-SA/PVA dispersions preserve colloidal stability across diverse latex systems.As a practical demonstration,M-SA-reinforced chlorosulfonated polyethylene(CSM)rubber latex composites show more than a 50%reduction in thermal conductivity while maintaining chemical resistance,enabling high-performance insulating protective gloves and coatings.This work establishes a critical link between aerogel surface chemistry and aqueous processing stability,providing a mechanistic foundation for the rational design of water-based rubber/silica aerogel composites and next-generation thermal insulation materials.展开更多
To combine the high elasticity and good mechanical performance of isoprene rubber(IR)with excellent fatigue resistance and low heat build-up of Eucommia ulmoides gum(EUG),the present study employed a chemical method t...To combine the high elasticity and good mechanical performance of isoprene rubber(IR)with excellent fatigue resistance and low heat build-up of Eucommia ulmoides gum(EUG),the present study employed a chemical method to graft 4-amino pyridine(AP)onto epoxidized IR and EUG,thereby creating a chemical assembly rubber of amino-pyridine-grafted epoxidized IR(AP-EIR)and amino pyridine-grafted epoxidized EUG(AP-EEUG)via a dynamic hydrogen bonding network.The presence of hydrogen bonds between AP-EIR and AP-EEUG was confirmed by variable temperature infrared spectroscopy,whereas scanning electron microscopy-energy dispersive spectroscopy revealed a uniform dispersion of zinc oxide and nano-fillers.Hydrogen bonds significantly facilitate strain-induced crystallization between the AP-EIR and AP-EEUG molecules,thereby strengthening their intermolecular interactions.During mechanical deformation,the material primarily dissipates energy through the breaking of hydrogen bonds,which effectively improves the mechanical strength of the material,and the introduction of amino groups in this chemical assembly rubber improves the uniform dispersion of nano-fillers,as well as the interface interaction between rubber and nano-fillers.Consequently,the chemically assembled rubber exhibited superior modulus,tensile strength,and tear strength compared to IR and its physical blend,while also demonstrating reduced heat build-up during dynamic loading.展开更多
基金financially supported by the National Key Research and Development Program of China(Nos.2022YFC2603500,2022YFC2603502)the Guangzhou Science and Technology Project(No.2024A04J4280).All authors acknowledge the financial support.
文摘Silica aerogels(SAs)impart low density and excellent thermal insulation to polymer systems,yet incorporating hydrophobic SAs into aqueous rubber latex systems remains challenging owing to their poor dispersibility and potential to destabilize the latex.Although previous studies have dispersed SAs in aqueous poly(vinyl alcohol)(PVA),the stability of such dispersions and their effectiveness as bridging media for latex integration have not been thoroughly evaluated,which limits their practical application in latex compounding.This study systematically examined how the surface chemistry governs hydrolytic stability,interfacial behavior,and latex compatibility in PVA-assisted aqueous processing.Two hydrophobic SAs were prepared:ethoxy-modified SA(E-SA)and methyl-modified SA(M-SA).Both initially formed a homogeneous PVA slurry,but E-SA rapidly hydrolyzed its surface—OCH_(2)CH_(3)groups,releasing ethanol,becoming hydrophilic,and undergoing irreversible nanopore collapse.In contrast,M-SA maintains its structural integrity and hydrophobicity because its—Si(CH_(3))_(3)groups are highly resistant to hydrolysis.This divergence dictates the behavior during latex blending.The ethanol released from E-SA disrupts electrostatic and steric stabilization,inducing latex coagulation,whereas M-SA/PVA dispersions preserve colloidal stability across diverse latex systems.As a practical demonstration,M-SA-reinforced chlorosulfonated polyethylene(CSM)rubber latex composites show more than a 50%reduction in thermal conductivity while maintaining chemical resistance,enabling high-performance insulating protective gloves and coatings.This work establishes a critical link between aerogel surface chemistry and aqueous processing stability,providing a mechanistic foundation for the rational design of water-based rubber/silica aerogel composites and next-generation thermal insulation materials.
基金financially supported by the National Natural Science Foundation of China(No.52341301)Liaoning Provincial Department of Education Basic Research Project,China(Nos.LJKZZ20220055 and JYTMS20231498)Shenyang Natural Science Foundation Special,China(No.23-503-6-06).
文摘To combine the high elasticity and good mechanical performance of isoprene rubber(IR)with excellent fatigue resistance and low heat build-up of Eucommia ulmoides gum(EUG),the present study employed a chemical method to graft 4-amino pyridine(AP)onto epoxidized IR and EUG,thereby creating a chemical assembly rubber of amino-pyridine-grafted epoxidized IR(AP-EIR)and amino pyridine-grafted epoxidized EUG(AP-EEUG)via a dynamic hydrogen bonding network.The presence of hydrogen bonds between AP-EIR and AP-EEUG was confirmed by variable temperature infrared spectroscopy,whereas scanning electron microscopy-energy dispersive spectroscopy revealed a uniform dispersion of zinc oxide and nano-fillers.Hydrogen bonds significantly facilitate strain-induced crystallization between the AP-EIR and AP-EEUG molecules,thereby strengthening their intermolecular interactions.During mechanical deformation,the material primarily dissipates energy through the breaking of hydrogen bonds,which effectively improves the mechanical strength of the material,and the introduction of amino groups in this chemical assembly rubber improves the uniform dispersion of nano-fillers,as well as the interface interaction between rubber and nano-fillers.Consequently,the chemically assembled rubber exhibited superior modulus,tensile strength,and tear strength compared to IR and its physical blend,while also demonstrating reduced heat build-up during dynamic loading.
