Photopolymerization under various monochromatic UV/visible LEDs and IR lamp: Diamino-anthraquinone derivatives as versatile multicolor photoinitiators

Development of Drug-Loaded PCL@MOF Film Enclosed in a Photo Polymeric Container for Sustained Release

The programmed fabrication of oral dosage forms is associated with several challenges such as controlled loading and disintegration. To optimize the drug payload, excipient breakdown, and site-specific sustained release of hydrophobic drug (sulfamethoxazole, SM), we propose the development of acrylate polymer tablets enclosed with drug-loaded polycaprolactone (PCL) films. The active pharmaceutical ingredient (API) is physisorbed into the porous iron (Fe)-based metal-organic framework (MOF) and later converted to tangible PCL films, which, upon folding, are incorporated into the acrylate polymer matrices (P1/P2/P3). X-ray powder diffraction (XRPD) analysis and scanning electron microscopy (SEM) micrographs confirmed the stability and homogeneous distribution of MOF within the 50 μm thick film. Adsorption-desorption measurements at ambient temperatures confirmed the decrease in the BET surface area of PCL films by 40%, which was ∼3.01 m/g, and pore volume from 30 to 9 nm. The decrease in adsorption and surface parameters could confirm the gradual accessibility of SM molecules once exposed to a degrading environment. Fourier transform infrared (FTIR) analyses of in vitro dissolution confirmed the presence of the drug in the MOF-PCL film-enclosed tablets and concluded the cumulative SM release at pH ∼ 8.2 which followed the order SM@Fe-MOF < P1/P2/P3 < PCL-SM@Fe-MOF < P1/PCL-SM@Fe-MOF < P3/PCL-SM@Fe-MOF. The results of the study indicate that the P3/PCL-SM@Fe-MOF assembly has potential use as a biomedical drug delivery alternative carrier for effective drug loading and stimuli-responsive flexible release to attain high bioavailability.

High-Performance UV-Vis Light Induces Radical Photopolymerization Using Novel 2-Aminobenzothiazole-Based Photosensitizers

The popularity of using the photopolymerization reactions in various areas of science and technique is constantly gaining importance. Light-induced photopolymerization is the basic process for the production of various polymeric materials. The key role in the polymerization reaction is the photoinitiator. The huge demand for radical and cationic initiators results from the dynamic development of the medical sector, and the optoelectronic, paints, coatings, varnishes and adhesives industries. For this reason, we dealt with the subject of designing new, highly-efficient radical photoinitiators. This paper describes novel photoinitiating systems operating in UV-Vis light for radical polymerization of acrylates. The proposed photoinitiators are composed of squaraine (SQ) as a light absorber and various diphenyliodonium (Iod) salts as co-initiators. The kinetic parameters of radical polymerization of trimethylolpropane triacrylate (TMPTA), such as the degree of double bonds conversion (C%), the rate of photopolymerization (Rp), as well as the photoinitiation index (Ip) were calculated. It was found that 2-aminobenzothiazole derivatives in the presence of iodonium salts effectively initiated the polymerization of TMPTA. The rates of polymerization were at about 2 × 10-2 s-1 and the degree of conversion of acrylate groups from 10% to 36% were observed. The values of the photoinitiating indexes for the most optimal initiator concentration, i.e., 5 × 10-3 M were in the range from 1 × 10-3 s-2 even to above 9 × 10-3 s-2. The photoinitiating efficiency of new radical initiators depends on the concentration and chemical structure of used photoinitiator. The role of squaraine-based photoinitiating systems as effective dyeing photoinitiators for radical polymerization is highlighted in this article.

Radical photoinitiation with LEDs and applications in the 3D printing of composites

Radical initiation upon LED light irradiation is discussed herein as well as its application in additive manufacturing. The ability of manufacturing complex structures, freedom of design, low energy consumption, fast prototyping, and excellent spatial resolution are the main benefits of the 3D printing technology by photopolymerization. Therefore, the 3D printing of composites through photopolymerization processes is developing rapidly in the academia and industry, and has been a turning point of additive manufacturing (AM). In the present review, an overview of radical initiation with LEDs (i.e., the photopolymerization LED technology, the photoinitiating systems, and the polymerizable media) and of the main 3D printing methods by photopolymerization, materials, and their applications in different fields has been carried out. As a challenging topic, the issue of light penetration in a filled matrix for the access to composites is discussed, including the light transmittance of the composite, the mismatch of the refractive index between the filler and the monomer, the factors of the filler, and the adverse influence of low light penetration on the 3D printing process. In particular, the popular applications of 3D printing by photopolymerization in biomedical science, electronic industry, materials for adsorption, and 4D printing are discussed. Overall, this review gives an overview of the 3D printing of polymer matrix composites through photopolymerization processes as a benchmark for future research and development.