A blue-light curing system is used to prepare high-absorbing high-performance hydrogels

The use of Blu-ray curing system to prepare high-absorbing high-performance hydrogel
keywords
hydrogel visible light curing Blu-ray high-performance
hydrogel is a three-dimensional polymer network structure that can absorb and retain a certain amount of moisture. Hydrogels are widely used in many applications such as biomedical engineering and pharmaceutical products because of their high regulatory and biosysorance. Acrylic and acrylamide monosomes, because of their high hydrophobility and responsiveness, are widely used in the production and manufacture of hydrogels

. At the same time, through different polymer designs, hydrogel network structures with different physical and mechanical properties can be obtained.
UV curing is one of the most common curing techniques in radiation curing technology. In addition, there is a technology that is often used in the preparation of biological materials, that is, visible light curing technology. Compared with UV curing, visible light curing has many advantages such as high efficiency, safety, environmental friendliness and energy saving for the preparation of hydrogels. In the preparation of bio-hydrogel materials, visible light curing uses less energy and produces lower temperatures, which is important for the preparation of drug-given materials or cell-loaded hydrogels.
in visible light curing, blue light is an ideal light source because of its high energy and safety characteristics. the combination of(CQ) and xenon-based iodine hexafluorophosphate (DPI) is well absorbed in the blue light band and has high light sensitivity, so the CQ/DPI combination is widely used in blue light curing. Professor Yan Jianzhong of Zhejiang University of Technology and others studied the process of co-polymerization of CQ/DPI combined light triggers in the case of blue light.
main materials used in the preparation of hydrogels, including N, N-dimethyl acrylamide (DMAA), polyglycol diacrylates (PEGDA), and sodium acrylic (SA). The preparation process for the hydrogel membrane is to mix the light triggers CQ and DPI, polymerized monogams PEGDA and DMAA, and deionized water to obtain a water solution, which is then coated on a glass plate. The coating thickness is adjusted to about 0.3 mm, and another glass plate is used to form the sandwich structure. Then use a 100-watt blue LED light for five minutes to get the hydrogel film, and then carry out the corresponding performance test. In addition, Photo DSC is used to study the process of hydrogel polymerization.
experiments have found that light-trigger combinations containing DPI, such as CQ/EDB/DPI and CQ/DPI, have better trigger performance than other light-trigger combinations and are more polymerized (Figure 3, pink and blue). At the same time, the CQ/EDB/DPI combination showed the highest aggregation rate (Figure
3a, Rpmax approximately 8×10-
5

-1
, pink
), while the CQ/DPI combination showed the highest two-key conversion rate (Figure 3b, approximately 90%, blue).
results show that DPI plays an important role in accelerating light expeditement. This effect is related to the reaction paths in which both possible DPIs are involved: light reduction and photooxidation.
addition, the light polymerization velocity and the concentration of CQ show a linear relationship, although this relationship exists only if the CQ concentration is relatively low (<1.0%). A large deviation occurs when the concentration of CQ exceeds 1%, a phenomenon known as the "filtering effect" (Figure 4). That is, at high CQ concentrations, when light hits the coating surface, the polymerization reaction occurs quickly and a curing layer is formed on the surface. This curing layer limits the penetration of light deeper, resulting in reduced overall polymerization efficiency.
gel preaccols using CQ/DPI and CQ/EDB/DPI-triggered systems exhibit typical gel behavior at lighting of approximately 30 and 40 seconds, while only two gel preconses using CQ or CQ/EDB do not exhibit gel behavior.
DMAA also showed self-association (Figure 5). Twoare produced by removing one hydrogen from the methyl of DMAA by using xenon or benzene free fundamentals, or by extracting one hydrogen from a double bond. PDMAA is then obtained by the addition aggregation of DMAA free fundamentals of Type I and Type II. Through this ability of self-intersecting, DMAA also manifests itself as a trigger in the trigger process.
figure 6, the stress of the DMAA/SA hydrogel containing different CQ concentrations becomes 20 times or greater and increases as the CQ concentration increases. For stress, when the CQ concentration increases from 0.125 to 0.5, the stress increases first and then decreases. During the increase of CQ concentration to 1.25, stress showed a maximum value of 0.6MPa when CQ was 0.5%. As the CQ concentration increases, the crosslink density increases. But at the same time, as the extra amount of trigger increases, regionalized and smaller molecular structures are formed, resulting in weaker cross-networked structures with reduced strength.
composition of the polymer monomer, also known as the DMMA/SA ratio, is another important factor affecting the performance of polymer hydrogels. As the DMMA/SA ratio increases, the strain increases and the stress changes in different directions. In addition to the composition of the monosome, other factors include crosslinker type, crosslinker dosage, monosome concentration and DPI concentration have some effect on the mechanical properties of the material.
the polymer DMMA/SA hydrogel performs extremely well mechanically (Figure 7). A 2 mm diameter hydrogel strip can be knotted and stretched well without breaking, and can also carry up to 250 grams.
pure PDMAA hydrogels show poor water absorption due to the lack of a strong hydro-water-based group in the structure. The addition of sodium acrylic, or pyridine-based, makes the water absorption of PDMAA network greatly increased. When the DMMA/SA ratio is 4:6, the water absorption reaches a maximum of 618g/g. Using PEGDA as an additional crosslinker can regulate the absorbent properties of hydrogels. At 0.1-0.5% of PEGDA usage, the absorption capacity can be adjusted between 210-740g/g, with a peak of 0.2wt. Hydrogel materials still exhibit very good dimensional stability and regulation at maximum water absorption.
the work of Professor Yan Jianzhong and others shows that the hydrogel system can be rapidly gelding and polymerization under visible blue light exposure with appropriate CQ/DPI combination light triggers, and has a high double-bond conversion rate. Through this visible light polymerization process, a polyDMAA/SA hydrogel with ultra-strong absorbent and robust aesthetic properties can be obtained, and the material also has good dimensional stability. This work will bring new directions and guidance to the design and synthesis of customized hydrogels for biomedical applications.
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