Abstract
The development of visible-light 3D printing technology by using water-soluble initiating systems has attracted widespread attention due to their potential applications in the manufacture of hydrogels. Besides, at present, the preparation of water-soluble photoinitiators suitable for visible light irradiation (such as LEDs) still remains a challenge. Therefore, this work is devoted to developing water-soluble photoinitiators (PI)/photoinitiating systems (PIS) upon irradiation with a LED @ 405 nm. In detail, a new water-slightly-soluble chalcone derivative dye [(E)-3-(4-(dimethylamino) phenyl)-1-(4-(2-(2-(2-methoxyethoxy) ethoxy) ethoxy) phenyl) prop-2-en-1-one] was synthesized here and used as a PI with a water-soluble coinitiator, i.e., triethanolamine (TEA) which was also used as an electron donor. When combined together, a charge transfer complex (CTC) formed immediately which exhibited excellent initiating ability for the free radical photopolymerization of poly(ethyleneglycol)diacrylate (PEG-DA). In light of the powerful CTC effect, the [dye-TEA] CTC could not only exhibit enhanced water solubility and mechanical properties but could also be effectively applied for 3D printing. This CTC system is environmentally friendly and cost-saving which demonstrates a great potential to prepare hydrogels via photopolymerization.
Highlights
During the last decades, photopolymerization has been the focus of intense research efforts due to the wide range of applications in which this polymerization technique is involved
The free radical photopolymerization monomers used in this work, namely, polyethThe free radical photopolymerization monomers used in this work, namely, polyethylene glycol diacrylate (PEG-diacrylate: SR 610) was purchased from Sartomer-Europe ylene glycol diacrylate (PEG-diacrylate: SR 610) was purchased from Sartomer-Europe (Colombes, France)
As proved to be a simple and effective method to enhance the solubility in water. Another strategy for preparing water-soluble photoinitiating systems (PIS) is proposed, which consists in just mixing the dye exhibiting a poor solubility with a water—oil amphiphilic TEA at the saturation concentration to form the charge-transfer complex (CTC) and increase the solubility of the dye
Summary
Photopolymerization has been the focus of intense research efforts due to the wide range of applications in which this polymerization technique is involved. The polymerization process can be extremely fast, enabling it to reach high fabrication speed and making photopolymerization suitable for biomedical applications (e.g., tissue engineering, drug delivery systems, medical devices, etc.) [1,2,3]. The combination of this process with 3D printing technology can provide an efficient tool to elaborate structures with a high precision of shape using hydrogels and enabling to achieve the fusion of structure and function. The design and synthesis of PI or PIS with good water solubility, non-toxicity, high photoactivity, high initiation efficiency, low volatility and high migration stability is still a research hotspot in this field
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