To reduce the polymerization shrinkage of the dental resin composites, a new liquid-crystalline resin monomer was developed. The acrylate liquid crystalline resin monomer (ALCRM), (4-3-(acryloyloxy)-2-hydroxypropoxy) phenyl 4-(3-(acryloyloxy)-2-hydroxypropoxy) benzoate, was synthesized by a three-step method. Using the ALCRM as the main monomer, the degree of conversion (DC) and the volume shrinkage of the resin matrix were compared with the traditional composite resin monomer (Bis-GMA), 2,2-bis[4-(2-hydroxy-3-methacryloyloxy-propoxy)-phenyl] propane. The new monomer showed liquid crystalline characteristics with a mesomorphic phasetransition temperature between 18ºC and 42ºC. When copolymerized with triethylene glycol dimethacrylate (TEGDMA) at a weight ratio of 7:3, the DC of ALCRM was higher and the volume shrinkage was 3.62±0.26%, which was less than that of the Bis-GMA. The ALCRM exhibits promising potential for the development of superior dental resins with low volume shrinkage.

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Different percentages of Fe 2 O 3 are composited with ZnO via a chemical precipitation method which is shown to be more efficient and convenient than other methods. The obtained products are analyzed by using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflection spectra (DRS), photoluminescence (PL), and vibrating sample magnetometer (VSM). Rhodamine B (RhB) dye is used as a simulated pollutant to cause degradation under UV light. Degradation efficiency is used to evaluate the photocatalytic activity of the composite catalysts. Compared with other samples, the results indicate that 7 wt.% ZnO/Fe 2 O 3 composite shows the highest photocatalytic activity for RhB dye. Furthermore, the particles reduce secondary pollution and prolong the service life of the photocatalyst. The addition of a magnetic carrier allows the composite catalyst to be better separated from the reflection media.

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