This study aimed to reveal the interaction between self-assembled multilayers and dye molecules in the environment, which is closely related to the multilayers' stable performance and service life. In this work, the pH-responsive poly (N-isopropylacrylamide-co-2-(dimethylamino) ethyl methacrylate) microgels were prepared by free-radical copolymerization and self-assembled with sodium alginate (SA) into multilayers by the layer-by-layer deposition method. Quartz crystal microbalance (QCM) and atomic force microscopy (AFM) results confirmed the construction of multilayers and the absorbed mass, resulting in a decrease in the frequency shift of the QCM sensor and the deposition of microgel particles on its surface. The interaction between the self-assembled SA/microgel multilayers and anionic dyes in the aqueous solution was further investigated by QCM, and it was found that the electrostatic attraction between dyes and microgels deposited on the QCM sensor surface was much larger than that of the microgels with SA in multilayers, leading to the release of the microgels from the self-assembled structure and a mass loss ratio of 27.6%. AFM observation of the multilayer morphology exposed to dyes showed that 29% of the microgels was peeled off, and the corresponding microgel imprints were generated on the surface. In contrast, the shape and size of the remaining self-assembled microgel particles did not change.

The preparation and application of functional hydrogels based on natural polysaccharides have always been a hot research topic. In this study, using acrylamide (AM) monomer, N, N'-methylene bisacrylamide (MBA) as cross-linking agent, potassium persulfate (K2S2O8) as initiator, in the presence of natural polysaccharide sodium alginate (SA), the PAM/SA hydrogel was prepared by free radical polymerization. Fourier transform infrared spectroscopy (FT-IR), swelling performance tests, scanning electron microscope (SEM), thermogravimetric analysis (TGA), UV-visible spectrophotometer, mechanical property measurements were carried out to analyze the composition, morphology, and performance of the hydrogels. The swelling behavior, dye adsorption performance, and the mechanical properties of PAM/SA hydrogels before and after Fe3+ adsorption were studied. The experimental results showed that the introduction of SA with 4.7%, 7.8%, and 10.3% effectively improved the mechanical and dye adsorption properties of PAM composite hydrogels. The adsorption capacity of PAM/4.7%SA and PAM/10.3%SA hydrogels at equilibrium can reach 40.01 and 44.02 mg/g for methylene blue, which is higher than the value 13.58 mg/g of pure PAM hydrogel. The compressive strength of pure PAM hydrogel is 0.124 MPa. When the SA content is 4.7%, 7.8%, and 10.3%, the compressive strength of the PAM/SA hydrogel was corresponding to 0.130 MPa, 0.134 MPa, and 0.152 MPa, respectively. Fe3+ was introduced into the PAM/SA hydrogels, and PAM/SA/Fe3+ double-network hydrogels with excellent mechanical properties could be prepared by adjusting the SA content (4.7%, 7.8%, and 10.3%), soaking time (1 h, 2 h, 3 h, 4 h, 5 h, 6 h), and Fe3+ concentration (4.76%, 7.41%, 9.09%, and 13.04%). Under the same Fe3+ concentration of 9.09% and adsorption time of 4 h, the compressive strengths of the PAM/4.7%SA, PAM/7.8%SA, and PAM/10.3%SA hydrogels could reach 0.354 MPa, 0.767 MPa, and 0.778 MPa, respectively.

In this study, organically modified montmorillonite (OMMT) was prepared by modifying MMT with a cationic surfactant cetyltrimethylammonium bromide (CTAB). The obtained OMMT of different loading contents (1, 2, 4, 6, and 8 wt %) was melt-blended with poly(acrylonitrile-co-butadiene-co-styrene) (ABS) to prepare a series of ABS/OMMT composites, which were laser marked using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser beam of 1064 nm under different laser current processes. X-ray diffraction (XRD), color difference spectrometer, optical microscope, water contact angle tests, scanning electron microscope (SEM), and Raman spectroscopy were carried out to characterize the morphology, structure, and properties of the laser-patterned ABS composites. The effects of the addition of OMMT and the laser marking process on the mechanical properties of ABS/OMMT composites were investigated through mechanical property tests. The results show that the obtained ABS/OMMT composites have enhanced laser marking performance, compared to the ABS. When the OMMT content is 2 wt % and the laser current intensity is 9 A, the marking on ABS composites has the highest contrast (ΔE = 36.38) and sharpness, and the quick response (QR) code fabricated can be scanned and identified with a mobile app. SEM and water contact angle tests showed that the holes, narrow cracks, and irregular protrusion are formed on the composite surface after laser marking, resulting in a more hydrophobic surface and an increased water contact angle. Raman spectroscopy and XRD indicate that OMMT can absorb the near-infrared laser energy, undergo photo thermal conversion, and cause the pyrolysis and carbonization of ABS to form black marking, and the crystal structure itself does not change significantly. When the 2 wt % of OMMT is loaded, the tensile strength, elongation at break, and impact strength of ABS/OMMT are increased by 15, 20, and 14%, respectively, compared to ABS. Compared with the unmarked ABS/OMMT, the defects including holes and cracks generated on the surface of the marked one lead to the decreased mechanical property. The desirable combination of high contrast laser marking performance and mechanical properties can be achieved at an OMMT loading content of 2 wt % and a laser current intensity of 9 A. This research work provides a simple, economical, and environmentally friendly method for laser marking of engineering materials such as ABS.