Increasing coatings, including varnishes and printing inks, and dental fillings objects are solidified with light. However, uniform polymer networks cannot be prepared, and the materials are often brittle, which limits the application of photopolymers in 3D printing, biomedicine, and microelectronics. In the journal Angewandte Chemie, the researchers present a new method, based on methacrylates, to produce homogeneously crosslinked tough polymers, even for 3D printing at high resolutions.
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Light curing is usually a free radical chain polymerization. The initiator is decomposed into free radicals by light energy, and attacks monomers, such as the C=C double bond in vinyl, to form a new free radical, which becomes the growth of the polymer network by attacking more monomers and combining with them starting point.
New methods of controlling free radical photopolymerization and improving the material properties of products tend to reduce Slow curing process, which is not ideal for 3D printing. Short irradiation periods are crucial for high spatial resolution and economical production times.
A research group led by Robert Liska at the Technical University of Vienna (Austria) has developed a new approach, methacrylate-based photopolymers without inhibiting the curing process. They used ester-activated vinyl sulfonate (EVS) as a chain transfer agent because it can be easily detached from a part of itself to activate the process.
If the growing polymer network attacks EVS instead of another monomer, then Intermediates are formed and rapidly split to form terminating polymer chains and highly reactive groups (tosyl groups) in the network, which in turn initiate new chain reactions. The more EVS added, the shorter the average chain length of the polymer network. Since the shorter polymer chains remain more mobile, the risk of shrinkage leading to cracks during curing is significantly reduced. In contrast to conventional chain transfer agents, the polymerization is not inhibited in this new method, since there are no stable intermediates or reversible reaction steps, so the isolation of the tosyl group is advantageous.
To test it, the researchers built a scaffold-like Sample structure. With a thickness of 50 μm, the individual layered structures are well resolved. The material is very homogeneous, strong yet elastic and impact resistant, with high tensile strength. These properties can be adjusted by changing the number of EVS added. Without EVS, the material would be too brittle to 3D print. The new method could make tough photopolymers for biomedical applications, such as shape memory polymers for tissue growth and tooth fillings.
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In fact, in recent years, we both found. As long as it’s about teeth, it’s not cheap. Scientists have also been working on innovative research and development of new dental filling materials.
Silicone rubber denture soft lining material can alleviate the problems of mucosal tenderness and poor retention during the use of complex removable dentures. In recent years, research on its antibacterial modification has become a hot spot, but the addition of antibacterial agents is likely to affect its physical and chemical properties.
Experiments have found that the nano silver phosphoric acid Zirconium antibacterial agent (AgZ) was added to the silicone rubber soft lining matrix to prepare silver-loaded zirconium phosphate/silicone rubber composite soft lining materials. The experimental results are as follows:
1. The silver-loaded zirconium phosphate nanoparticles can be evenly dispersed in the silicone rubber soft lining by high shear emulsification dispersion method to make a composite material , has the advantages of simple process, short required time and high efficiency.
2. Nano silver-loaded zirconium phosphate can be used as an antibacterial agent To improve the mechanical properties of silicone rubber soft lining materials, the tensile strength, tearing strength, The strength and roughness increased significantly; when the addition ratio was 2% and 5%, the hardness of the silver-loaded zirconium phosphate/silicone rubber composite soft lining material did not increase significantly.
3. Silver-loaded zirconium phosphate/silicone rubber composite soft Compared with ordinary silicone rubber soft lining materials, the blending time of the lining material is prolonged, the consistency is slightly increased, and the working time and curing time are slightly shortened.
4. When the addition ratio is 2% and 5% , silver-loaded zirconium phosphate/silicone rubber composite soft lining material antibacterial agent dispersed evenly, the mechanical properties were significantly improved and the change in hardness was not significant, and the change in operational performance was small. Combined with the results of the previous antibacterial experiment, the antibacterial effect of the 5% group was better than that of the 2% group , it can be considered that the addition mass ratio is 5% more appropriate.