Extended Applicability of Classical Phenolphthalein: Color Changing Polymeric Materials Derived from pH-Sensitive Acrylated Phenolphthalein Derivatives

Abstract

Polymerizable phenolphthalein derivatives with pH-sensitive properties were synthesized in the course of electrophilic aromatic substitution reactions. 4) were obtained and characterized. Copolymerization of 3 and 4 with acrylic acid (5a), N-(isopropyl)acrylamide (5b), and N,N-dimethylacrylamide (5c) enabled the synthesis of color switchable materials. Thereby, water-soluble pH sensitive linear polymers 6 and 7 were prepared using monomer 3. Additionally, cross-linked polymers 8 were prepared successfully by copolymerization of 4 and 5c. These pH-sensitive polymers form hydrogels in aqueous solution. Linear viscoelastic behavior depending on the concentration of the cross-linker was observed.

Polymers and Dyes: Developments and Applications

“…As another example of polymerizable triphenylmethane dyes, a radically polymerizable phenolphthalein derivative was obtained through reaction of phenolphthalein with N-(hydroxymethyl)acrylamide [57][58][59]. The latter compound possesses a relatively high reactivity towards nucleophilic attacks, which enables condensation with electron-rich aromatic substances under Friedel-Crafts-like conditions.…”

“…Moreover, the diacrylated phenolphthalein derivative can be used as a cross-linker to form superabsorbent and insoluble polymers while still being pH-sensitive. Therefore, these polymers are suggested for reusable materials for analytical purposes to indicate basic medium [57]. The color change of a cross-linked phenolphthalein-containing polymer from acidic to basic medium and back is shown in Figure 11.…”

Development of water‐based polymeric dye and its application as a colorant for waterborne polyurethane

“…WPD has been widely applied in different areas such as printing, textile dyeing, and hair dyeing . The applications of WPD in pH indication and iris implants are also under research . A lot of researches have verified that WPD is more superior than tradition dyes in terms of affinity, colorfastness, and safety …”

“…The application of WPD is limited by high production cost and complicated synthesis process . Hassabo et al .…”

Color Indicator for Supramolecular Polymer Chemistry: Phenolphthalein‐Containing Thermo‐ and pH‐Sensitive N‐(Isopropyl)acrylamide Copolymers and β‐Cyclodextrin Complexation

“…This results in an increasing delocalization of the π‐electron system, which causes a color change from colorless to purple. With the intention to reduce the toxicity, we modified phenolphthalein by introducing polymerizable groups in a previous study 3. By the use of a phenolphthalein‐acrylamide derivative, water‐soluble polymeric materials were prepared that showed the desired pH sensitivity.…”