Bolesław Szadkowski , Wojciech Raj , Emmanuel Beyou , Joanna Pietrasik , Anna Marzec
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引用次数: 0
Abstract
This study focuses on the synthesis and characterization of novel pH-sensitive color materials based on alizarin, (1,2-dihydroxyanthraquinone), a natural pigment with versatile properties. The polymer-based indicators were prepared by grafting poly(methyl methacrylate) (PMMA) and poly(2-hydroxyethyl methacrylate) (PHEMA) from alizarin through an ester pH-liable bond, allowing for easy tunability of their physicochemical properties. The synthesis process involved the esterification of alizarin using 2-bromo-2-methylpropionyl bromide, facilitated by triethylamine as an acid scavenger. The resulting alizarin served as a difunctional initiator for atom transfer radical polymerization (ATRP) of methyl methacrylate and 2-hydroxyethyl methacrylate. The molecular structures of the synthesized hybrids were confirmed using 1H NMR and GPC analyses. The color characteristic, surface energy, thermal stability, and pH sensing activity of the alizarin-based hybrids were studied according to the type of grafted polymer nature as well as their degree of polymerization. PHEMA-grafted alizarin showed more rapid and more visible color changes under the influence of NH3 vapours compared to PMMA hybrids, due to their less hydrophobic nature. Furthermore, kinetic plots demonstrated various hydrolysis rates, with PMMA hydrolysis being slower than that of PHEMA due to its stronger hydrophobic character. UV–Vis spectra and GPC traces confirmed the occurrence of hydrolysis and successful cleavage of the ester bond links between the grafted polymers and alizarin with a decrease of the molar mass by a factor of two as expected. Such behavior offers opportunities for tailoring degradation profiles and achieving specific release profiles upon application of a wide range of polymers with varied character. The designed polymer-based pigments exhibited a high ability to monitor calorimetrically the pH changes, especially in alkaline conditions. Overall, this study contributes to the broadening of the application of alizarin-based materials, paving the way for further exploration and development in the field of functional materials.
期刊介绍：
Dyes and Pigments covers the scientific and technical aspects of the chemistry and physics of dyes, pigments and their intermediates. Emphasis is placed on the properties of the colouring matters themselves rather than on their applications or the system in which they may be applied.
Thus the journal accepts research and review papers on the synthesis of dyes, pigments and intermediates, their physical or chemical properties, e.g. spectroscopic, surface, solution or solid state characteristics, the physical aspects of their preparation, e.g. precipitation, nucleation and growth, crystal formation, liquid crystalline characteristics, their photochemical, ecological or biological properties and the relationship between colour and chemical constitution. However, papers are considered which deal with the more fundamental aspects of colourant application and of the interactions of colourants with substrates or media.
The journal will interest a wide variety of workers in a range of disciplines whose work involves dyes, pigments and their intermediates, and provides a platform for investigators with common interests but diverse fields of activity such as cosmetics, reprographics, dye and pigment synthesis, medical research, polymers, etc.
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