The Relationship Between The Distribution State Of SiO₂ Nanoparticles With Low SMA Modification Degree In The PS/PA6 Alloy System And The Molecular Structure Of SMA

For nanocomposites,a polymer alloy with a co-continuous structure can form a complete continuous structure due to its special structure and two-phase containing interface.It is a perfect polymer template to prepare thermal conductivity,electrical conductivity,electromagnetic interference shielding and other functional Nanocomposite.Recently,the method of reducing the percolation threshold of fillers by selectively distributing inorganic functional nanoparticles at a certain phase or interface of a polymer alloy with a co-continuous structure has attracted wide attention from researchers.By adjusting the selective distribution of nanoparticles in co-continuous alloys,it can help people design and prepare functional nanocomposites.Therefore,studying the distribution of inorganic nanoparticles in co-continuous alloys has great research value.The previous research of the research group proposed the use of dual compatibilizers with different molecular weights to realize the preparation of a stable co-continuous structure in an incompatible polymer alloy system with an asymmetric structure.And using the co-continuous PS/PA6 alloy as a template,the inorganic nanoparticles were successfully distributed at the interface of the co-continuous alloy by using different structure compatibilizer molecules to modify the surface of inorganic nanoparticles.However,in the previous work,the content of copolymers modified on the surface of the particles is still high,which affects the expression of the functions of the functional nanoparticles to a certain extent.Based on the previous work of the research group,this thesis first studied the relationship between the degree of surface modification of functional particles and their function attenuation.After that,the PS/PA6 co-continuous alloy was mainly used as the template,and four different styrene grafted maleic anhydride copolymers(SMA)were selected as the modifiers(SMA1:MAH=8wt.%,Mw=250000g/mol,SMA2:MAH=25wt.%,Mw=10000g/mol,SMA3:MAH=23wt.%,Mw=110000g/mol,SMA4:MAH=10wt.%,Mw=14400g/mol)Low surface modification of SiO₂ particles.A series of SiO₂-SMA particles were prepared to study the effect of the molecular structure(molecular weight and MAH content)of the surface modification of the particles on the selective distribution of the particles in the PS/PA6 alloy system under low modification degree.The main research work is as follows:1.The relationship between the degree of surface modification of functional nanoparticles and the attenuation of their functions was verified.ZnO nanoparticles with antibacterial properties were selected,and a series of ZnO-SMA particles were prepared by solution grafting and melt grafting.The results show that when the surface of ZnO particles is modified with SMA,its antibacterial performance decreases with the increase of the degree of modification,indicating that the surface grafted polymer has a certain inhibitory effect on the antibacterial performance of ZnO.Further,through a melt grafting method,SMAs with different molecular weights and MAH contents are grafted onto the surface of ZnO nanoparticles to obtain ZnO-SMA nanoparticles with a saturated degree of grafting.It is found that when the degree of surface modification reaches saturation,the antibacterial properties of ZnO nanoparticles decrease with the increase of the degree of grafting of the surface modifier,but it has nothing to do with the molecular weight of the graft.2.A series of low-modification SiO₂-SMA particles were prepared by solution grafting,and PS/PA6/SiO₂ co-continuous alloys were prepared with a fixed processing method and ratio.The distribution of SiO₂ particles in co-continuous alloys under low modification was studied.The relationship with the modified SMA molecular structure.The results show that when using low MAH content and high molecular weight SMA1 to modify SiO₂,as the grafting degree of the particle surface increases,the content of SiO₂ particles distributed at the interface increases.When using high MAH content SMA2 and SMA3 modified particles,the particles will only be distributed in the PA6 phase,and as the surface grafting degree increases,the SMA and PA6 on the surface of the SiO₂ particles will form more PA6-g-SMA.Its high proportion of PA6 makes the particles more likely to be distributed in the PA6 phase,and it is difficult to distribute at the interface.It has nothing to do with the molecular weight of the grafted SMA,and the best distribution effect at the interface is only 48%.Finally,when the particles are modified with SMA4 with low MAH content and low molecular weight,as the grafting degree increases,the distribution of the particles at the interface shows a trend of first increasing and then decreasing.When the surface of the SiO₂ particle PA6-g-SMA and the phase interface reach the best When the compatibility of the particles is only 0.79wt.%,the distribution of 88%at the phase interface can be achieved.That is,only a simple modification of the particles can make it achieve a higher interface distribution effect.This work mainly studied the relationship between the distribution of SiO₂ nanoparticles in the PS/PA6 bicontinuous system and the molecular structure of the grafted SMA under low modification degree,and prepared the PS/PA6/SiO₂ co-continuous alloy to achieve In order to graft 0.79wt.%of SMA4 on the surface of SiO₂,88%of the particles can be distributed at the PS/PA6/SiO₂ co-continuous alloy interface,which provided theories and methods for breaking through the bottleneck problem of preparing high-performance functional polymer composites.