炭黑纳米颗粒在纤维素表面吸附的分子动力学研究OA

Carbon black nanoparticles(CBNPs),as ubiquitous environmental and domestic pollutants,readily desorb from soiled garments and undergo secondary deposition onto clean fabrics during laundering,leading to cross-contamination.This process not only severely compromises the aesthetic quality of textiles but may also impair key wearability properties such as air permeability and mechanical performance.Current research on particulate contamination during washing predominantly focuses on macroscopic detergency evaluation,while mechanistic understanding of the nanoscale interfacial adsorption between pollutants and fiber substrates remains limited.Particularly for cotton fabrics,traditional studies have struggled to reveal the fundamental nature of the adsorption process,which significantly hinders the rational design of anti-redeposition detergent formulations and the optimization of washing processes. To systematically investigate the adsorption mechanism of CBNPs onto cotton fabrics,this study integrates experimental and simulation approaches.Firstly,on the experimental level,household laundering conditions were simulated by establishing multifactorial parameters,including CBNPs mass fraction gradients(0.20-1.00%),washing temperature gradients(30-90℃),laundering time gradients(30-90 min),and detergent dosage gradients(0.00-0.20 g).The adsorption behavior was characterized using field-emission scanning electron microscopy(FE-SEM),K/Svalues,whiteness index,Fourier-transform infrared spectroscopy(FTIR),and X-ray diffraction(XRD).Furthermore,surface adsorption molecular dynamics models were constructed,including a cellulose/CBNPs model and a cellulose/CBNPs-H2 O-LAS model incorporating water molecules and linear alkylbenzene sulfonate(LAS),to simulate their interfacial interactions via molecular dynamics simulations. With increasing concentration of CBNPs,their adsorption behavior on the surface of cotton fibers is significantly enhanced.Experimental observations show that not only does the number of CBNPs on the fiber surface increase,but the particles also aggregate and distribute unevenly across the surface and within the gaps,disrupting the originally smooth morphology of the fibers.Correspondingly,the fabric's K/S value increases significantly while the whiteness index decreases,confirming that particle deposition enhances light absorption and intensifies coloration.Molecular dynamics simulations reveal the underlying mechanism of this phenomenon.In the cellulose/CBNPs-H2 O-LAS composite system,the absolute value of the interfacial adsorption energy is greater than that in the simple cellulose/CBNPs system,indicating that the introduction of water and the surfactant LAS enhances the interfacial affinity between cellulose and CBNPs.Radial distribution function analysis further shows that the interaction peak between oxygen atoms bearing functional groups in CBNPs and oxygen atoms in cellulose is significantly strengthened in the model containing water and LAS,suggesting that hydrogen bonding or electrostatic interactions promote interfacial binding.Moreover,the mean square displacement of carbon atoms in CBNPs within this system is markedly reduced,indicating restricted particle mobility.This further confirms that more stable interactions are formed between CBNPs and the cellulose surface,thereby solidifying the adsorption state at the microscopic kinetic level.