Photocatalytic And Microwave Absorbing Properties Of Cadmium Sulfide/Carbon Nanotubes/Poly (Methyl Methacrylate) Composites

In this work,MMA-MAA Cd²⁺ ionomer have been prepared through neutralization of a carboxylated poly?methyl methacrylate?,i.e.,poly?methyl methacrylate-ran-methacrylic acid??MMA-MAA?,and take the ionomer as precursor,mixing with carbon nanotubes?CNTs?and the surfactant by ultrasonic dispersion.The porous fluffy composite precursor is obtained through freeze drying process,finally H2 S gas takes part in the reduction reaction,CdS/CNTs/PMMA composite materials is synthesized.The composite materials having different content of CNTs is obtained by changing the amount of CNTs.The reference is prepared by replace MMA-MAA copolymer with PMMA homopolymer to blend with?CH₃COO?₂Cd under the same process conditions.The photocatalytic properties of the composites were evaluated with CdS as the main research object,and the microwave absorption properties of the composites were evaluated with CNTs as the main research object.Gel permeation chromatography was used to detect weight distribution and purification effect of MMA-MAA,the molecular weight distribution has narrows,and the weight average molecular weight increased;it was detected from the Fourier transform infrared spectroscopy that Cd salt ionomers synthesis reaction did not react completely,and the neutralization degree of the reaction was obtained to be 55% by acid-base titration.Coordination modes between carboxyl groups and Cadium ion was analyzed to a combination structure of chelating and bridging.After entering the H₂S gas,the Cd ionomer was successfully recovered and the CdS/CNTs/PMMA composite was obtained.On the basis of wide-angle X-ray scattering detection of freeze-dryed CdS/CNTs/PMMA composite and CdS/CNTs/PMMA homopolymer reference,and the same samples that are subsequently melt-pressed at 220 ? for 6 min,the spectra showed that the freeze-dryed CdS/CNTs/PMMA composites without nano clusters are detected,however,the samples that are subsequently melt-pressed at 220 ? for 6 min has been found that the size of clusters is 1.1 nm;the freeze-dried reference samples were detected clusters of 2.3 nm,which is close to the samples that are subsequently melt-pressed at 220 ? for 6 min.The results show that the CdS in the CdS/CNTs/PMMA composite synthesized by the freeze-drying process is the quantum dot shape of the excimer,and the particle size is small enough that the WAXS can not be detected.Ultraviolet-Visible spectrophotometry show that CdS nanoclusters composite peaks showed blue shift compared with bulk CdS.Using Rhodamine B solution as the base material,and CdS/CNTs/PMMA composite materials containing excimer grade CdS quantum dots as the test sample,CdS/CNTs/PMMA homopolymer as reference,the effect of the size of CdS nanoclusters on the photocatalytic properties of composites was explored.When the content of CNTs is 0,the photocatalytic degradation of CdS composite materials containing excimer grade reached rate of 88% after the time of 140 min,significantly higher than the composite reference samples containing nano CdS.It attributed that excimer grade CdS has larger specific surface area than the later,which led to the higher photocatalytic activity under the same illumination condition.After the addition of CNTs,the photocatalytic effect of the composite becomes worse,and with the increase of CNTs content,the photocatalytic performance of the composites decreases.The vector network analyzer were used to test the electromagnetic parameters of CdS/CNTs/PMMA composite and CNTs/PMMA composite.The results showed that two kinds of composite materials are both dielectric loss absorbing materials,and the addition of CdS makes loss factor and reflection loss of the composite material have been enhanced in the low frequency region,when the electromagnetic wave frequency was increased,CdS the promotion effect will gradually weaken.