An Effective Green Porous Structural Adhesive for Thermal Insulating,Flame-Retardant,and Smoke-Suppressant Expandable Polystyrene Foam

To develop an efficient way to overcome the contradiction among flame retardancy,smoke suppression,and thermal insulation in expanded polystyrene(EPS)foams,which are widely used insulation materials in buildings,a novel"green"porous bio-based flame-retard ant starch(FRS)coating was designed from starch modified with phytic acid(PA)that simultaneously acts as both a flame retardant and an adhesive.This porous FRS coating has open pores,which,in combination with the closed cells formed by EPS beads,create a hierarchically porous structure in FRS-EPS that results in superior thermal insulation with a lower thermal conductivity of 27.0 mW·(m·K)^(-1).The resultant FRS-EPS foam showed extremely low heat-release rates and smoke-production release,indicating excellent fire retardancy and smoke suppression.The specific optical density was as low as 121,which was 80.6%lower than that of neat EPS,at 624.The FRS-EPS also exhibited self-extinguishing behavior in vertical burning tests and had a high limiting oxygen index(LOI)value of 35.5%.More interestingly,after being burnt with an alcohol lamp for 30 min,the top side temperature of the FRS-EPS remained at only 140℃with ignition,thereby exhibiting excellent fire resistance.Mechanism analysis confirmed the intumescent action of FRS,which forms a compact phosphorus-rich hybrid barrier,and the phosphorus-containing compounds that formed in the gas phase contributed to the excellent flame retardancy and smoke suppression of FRS-EPS.This novel porous biomass-based FRS system provides a promising strategy for fabricating polymer foams with excellent flame retardancy,smoke suppression,and thermal insulation.

In vitro and in vivo antibacterial activity of graphene oxidemodified porous TiO_(2) coatings under 808-nm light irradiation

Bio-inertness and post-surgery infection on titanium(Ti)are the main causes of failure of biomedical implants in vivo.Near-infrared(NIR)photoactivated antibacterial therapy including photothermal and photodynamic therapies has attracted increasing attention due to the high bactericidal efficiency and little side effects.Although micro-arc oxidation(MAO)is an effective method to improve the biological activity of Ti implants,the porous TiO_(2)coatings prepared by MAO do not respond to near-infrared(NIR)light to kill bacteria by the photothermal and photodynamic effects.In this work,graphene oxide(GO)-modified TiO_(2)coatings(TiO_(2)/GO)are prepared on Ti to improve the photothermal and photodynamic ability of the MAO coatings.The TiO_(2)/GO coatings exhibit excellent antibacterial activity both in vitro and in vivo against Streptococcus mutans(S.mutans)under 808-nm NIR light irradiation due to the synergistic effects rendered by hyperthermia and reactive oxygen species(ROS).The NIR light-responsive antibacterial MAO coatings have large potential in combating implant-associated infections in clinical applications.

UV-triggered Polymerization of Polyelectrolyte Composite Coating with Pore Formation and Lubricant Infusion

Porous coatings with the features of muti-interfaces and high specific surface area have emerged as an excellent material platform for the manipulation of porous structures.Layer-by-layer(Lb L)assembly technique has been widely used in preparing porous polyelectrolyte coatings.However,the efficient construction of stable film from the Lb L technique is still a question.Herein,we reported a new solution to construct a stabilized polyelectrolyte coating with porous structures.Inspired by the mechanical reinforcement of double-network hydrogel,we constructed the poly(ethylenimine)(PEI)/poly(acrylic acid)(PAA)coating by in situ photopolymerization of acrylic acid in the PEI network instead of assembling PEI and PAA.Compared with the Lb L films,the in situ polymerized coating kept higher stability after 30 iterations of friction.Porous structures could also be constructed after acid treatment,which was utilized to load lubricant to enhance the lubricating property of the coating.This work provides a new method for the construction of dynamic and stable polyelectrolyte coatings,expediting more development of practical applications.