Molecular Modification For Enhanced Functional Of PAEs And Optimization Of Plastic Additive Regulation Based On Theoretical Calculation

Phthalic acid esters(PAEs),as the most commonly used plasticizers,are widely used in plastic products because of their small molecular weight,easy to make,good ductility and flexibility.PAEs can act on chromosomes in biological cells and change the number of chromosomes,causing carcinogenic and teratogenic hazards,and seriously threatening the ecological environment and human health.Therefore,while taking into account the functionality of PAEs,it is of great significance to reduce the damage of PAEs to the environment.PAEs are diverse and rarely exist singly in the environment.It is time-consuming and laborious to obtain physical and chemical parameters such as functional and environmental characteristics of PAEs by experimental means,and may also harm the ecological environment and human health.Therefore,the missing data were supplemented by theoretical calculation method,and single effect and joint effect were processed for functional characteristics and environmental characteristics parameters of PAEs by quantum chemistry and mathematical methods.A three-dimensional quantitative structure-activity relationship(3D-QSAR)model was constructed according to the single effect and combined effect values of functional characteristics of PAEs and environmental behavior.Based on the information obtained from the model,the existing PAEs molecules were modified,and the functional and environmental parameters of the new PAEs molecules were predicted effectively,providing theoretical basis for the evaluation of the functional characteristics and environmental behavior of PAEs homologs.This paper will focus on how to give consideration to the functional characteristics and environmental characteristics of PAEs and reduce the potential harm to the environment while improving its functionality.In this study,the functional characteristics(flame retardancy,insulation and stability),biological toxicity and enrichment of various kinds of PAEs were evaluated comprehensively by using ideal point method,comprehensive index method and quartile position method respectively to obtain comprehensive evaluation value.On this basis,a 3D-QSAR model of PAEs comprehensive effect was constructed.The single and double site substituent modification scheme that significantly affected the comprehensive effect of PAEs was developed.The target molecule was modified and its functional characteristics and environmental friendliness were preliminarily explored.Then,the newly constructed 3D-QSAR model was evaluated in the non-modified functional evaluation system.Finally,a novel derivative molecule with an enhanced single function without reducing other functions and environmental friendliness was screened and designed.Building the comprehensive effect of3D-QSAR model has broken the traditional QSAR model can only be a single representation limitations of environmental effect,and based on the molecular virtual rhetorical device,combined with molecular docking and molecular dynamics simulation of the new features of PAEs derivatives and environmental effect mechanism of further analysis,confirmed the feasibility of comprehensive evaluation method,At the same time,the reliability and effectiveness of designing novel PAEs derivative molecules with enhanced functional properties by constructing PAEs multi-effect 3D-QSAR model were illustrated.In this study,the scoring function values of the biodegradability of three plasticizer degrading bacteria of PAEs molecule were standardized and objectively weighted by using range normalization method combined with entropy weight method,so as to characterize the comprehensive biodegradability of three plasticizer degrading bacteria of PAEs molecule.On this basis,the 3D-QSAR model of comprehensive biodegradability of PAEs molecule was constructed.Three kinds of environment-friendly PAEs derivatives(DEP-27,DEP-28 and DEP-29)were designed for synergistic degradation of microplastics by molecular modification of target molecules and evaluation of the functionality and environmental friendliness of PAEs.Microbial pathway simulation and reaction energy barrier calculation before and after modification of the newly designed derivatives showed that the reduction degree of microbial degradation energy barrier of PAEs derivatives was consistent with the proportion of comprehensive biodegradability improvement,confirming the validity of the comprehensive biodegradability model of PAEs.In addition,the molecular dynamics simulation showed that the binding ability of three plasticizer degrading bacteria was significantly increased,which could be used as methyl phthalate derivative molecules for co-degradation with microplastics,and also provided a directional selection and theoretical design method for the replacement of plasticizer.In this study,the ratio normalization method was used to characterize the comprehensive evaluation value of PAEs biodegradation in both Marine and freshwater environments,so as to construct a 3D-QSAR pharmacophore model that considered the comprehensive evaluation value of PAEs biodegradation,and designed five PAEs derivatives with improved biodegradation effect in both Marine and freshwater environments.The biodegradation pathway simulation showed that the biotoxicity and estrogenic toxicity of PAEs derivatives were lower than those of their precursors.Through the simulation of the UV degradation pathway,it was found that the energy barrier of O-OH fracture reaction of PAEs derivatives decreased during UV degradation,and the ·OH generated of the photodecomposition reaction could provide free radicals for the photodegradation of plastics in the environment,which confirmed the effectiveness of pharmacophore model.In addition,five environment-friendly PAEs derivatives were docked with other degradation enzymes in different environments,it was revealed that PAEs derivatives had good biodegradability in wetland soil and shallow aquifer sediment environment,confirming that the established pharmacophore model had certain universality.This study selected Marine ecosystems in detection of polystyrene plastic as the research object,using molecular dynamics method screening of plastic additives plastics degradability of the relative contributions of each component,at the same time utlise factorial design of experiment method and molecular dynamics simulation of phase coupling,regulating additive composition scheme,analysis of interaction mechanism between additive components,And screen the plastic component combinations that can be absorbed and degraded to the maximum extent by microorganisms.In this paper,plasticizers,antioxidants,light stabilizers,heat stabilizers,flame retardants,lubricants and fillers were selected as external stimuli affecting the biodegradability of plastics.Molecular dynamics simulation showed that plastic additives promoted the biodegradability of plastics.It was found that plasticizer was the most favorable factor for plastic degradation,the hydrophobic effect was the main reason for enhancing plastic degradation,and the most favorable combination of plastic additives was selected.The regulation scheme of plastic biodegradation effect based on additive component ratio optimization designed in this paper provides new ideas for the subsequent study of aquatic biodegradable plastics.