Development of novel reversible thermometer from N‐isopropylacrylamide and dicyanodihydrofuran hydrazone probe

Abstract

A simple‐structured polymeric colorimetric thermometer with selective colorimetric changes over a specific temperature range was developed. Thermo‐responsive poly(N‐isopropylacrylamide‐co‐Dicyanodihydrofuran hydrazone) [Poly(NIPAM‐co‐DCDHFH)] organogel imprinted with DCDHFH chromophoric probe was prepared via free radical polymerization. The DCDHFH chromophore bearing a vinyl group was prepared by azo‐coupling of DCDHF with a diazonium salt of 2‐amino‐5‐nitrophenol bearing a vinyl substituent. The poly(NIPAM‐co‐DCDHFH) consists of DCDHFH chromophore and N‐isopropylacrylamide (NIPAM) monomers. The chemical structure of DCDHFH probe was verified by 1H NMR and FT‐IR. The thermochromic property can be attributed to a heat‐stimulated polymer self‐assembly process controlling the inner hydrophobicity leading to charge delocalization on the molecular system of the DCDHFH chromophore. Poly(NIPAM‐co‐DCDHFH) functioned as a thermochromic detector displaying colorful shifts between yellow (422 nm) and blue (580 nm) with raising the temperature of the aqueous poly(NIPAM‐co‐DCDHFH). These color shifts were correlated to the temperature increment from 28 to 46°C owing to the phase changes of the poly(NIPAM‐co‐DCDHFH) copolymer in aqueous media. The morphological features of the organogel nanofibers were studied by transmission electron microscope (TEM) and scanning electron microscopy (SEM). The working mechanism accounting for the thermochromic performance of poly(NIPAM‐co‐DCDHFH) was explored. The cytotoxicity of the poly(NIPAM‐co‐DCDHFH) hydrogel was also evaluated. This is a significant study for a variety of potential applications, such as functional apparel and medicinal applications.

Preparation of Self-Healing Anthocyanidin-Containing Thermochromic Alginate Ink for Authentication Purposes

“…Using a Brookfield model DV-III (Stoughton, MA) with Brookfield software, we were able to ascertain the hydrogel ink (Cy 5 ) rheological characteristics. According to the previously reported procedure, 21 the rheometer was first leveled and autozeroed. Viscosities of the hydrogels were reported at different concentrations of anthocyanidin.…”

“…Functional materials are distinguished with native features and functions. , They can be reported as a category of engineered structures with suitable surface morphology. – In particular, a colorimetric thermometer is intriguing as it provides a straightforward tool for monitoring of temperature by the observation of colorimetric variations without the need for specialized equipment or trained staff . Paints, thermometer strips, inks, switchers, sensors, mapping probes, and smart windows are some of the numerous commercial and scientific applications of thermochromic pigments. – Due to their fast responsiveness, a nanoparticle polymer thermometer composed of nanostructured self-assemblies is of special interest. Thermometers based on polymers are often made using a number of different polymers and chromophores .…”