Highly Photoluminescent CdTe/Poly(N‐isopropylacrylamide) Temperature‐Sensitive Gels

Abstract

DAST nanocrystal dispersion having fixed anisotropy may be enhanced by orientational factors. ExperimentalDAST, lauryl acrylate, and tricyclo[5.2.1.0 2,6 ]decane-4,8-dimethanol diacrylate (TD) were purchased from Aldrich Co. Inc. n-Dodecyltrimethylammonium chloride (DTMAC) and benzoin isopropyl ether (BIPE) were purchased from Tokyo Kasei Co., Ltd. DAST and BIPE were recrystallized twice from methanol and toluene, respectively. The other reagents were used without further purification. An ethanol solution (50 lL) containing DAST (5 mM) and DTMAC (5 mM) was injected into lauryl acrylate (5 mL) containing BIPE (0.1 M) and TD (1 wt.-%) according to the reprecipitation method [2]. The average nanocrystal size was obtained using a DLS-7000 dynamic light scattering analyzer (Otsuka Electronics); the viscosity and refractive index of the dispersion were 4.0 mPa s at 25 C and 1.444 at 20 C, respectively. A sample was positioned between the two poles of an electromagnet (Fluxdial precision electromagnet control system, Applied Magnetics Laboratory Inc.), which can operate at magnetic flux densities of up to 2.5 T, and the absorption spectra of the DAST nanocrystals dispersed in lauryl acrylate solution were measured in both the Faraday and Voigt configurations using a personal computer, the electromagnet, the detectable light from a Xe lamp light source (passed through a polarizer), a JASCO CT-25C monochromator, and a 2023 photodiode detector (New Forcus Inc.). After nitrogen gas had been bubbled through the DAST nanocrystal acrylate dispersion for 20 min, photocuring was performed in the magnetic field by irradiating the sample with UV light from a 500 W high-pressure mercury lamp (UI-501C, USHIO). To fix the anisotropic orientation of the DAST nanocrystal dispersion, we used a superconducting magnet (S15/17/40RT/13 horizontal magnet system, Oxford) having an output of up to 17 T. The optical rotatory dispersion spectra were measured using a JASCO J-820 spectropolarimeter.

Dual Stimuli-Responsive Supramolecular Hydrogel Based on Hybrid Inclusion Complex (HIC)

“…After the temperature was further increased from 40°C, the intensity of the emission decreased, which was probably with the shrinkage of the PNIPAM block. 34,35 Reversibility in Gel-Sol Transitions via Thermal Change and Supramolecular Substitution. The supramolecular hydrogel we obtained contains two distinct and independent physical cross-links.…”

Interfacing a Tetraphenylethene Derivative and a Smart Hydrogel for Temperature-Dependent Photoluminescence with Sensitive Thermoresponse

“…16,29 Favorably, the cytotoxicity of the TPE derivatives was argued to be lower than that of colloidal PL inorganic quantum dots, such as CdTe. 4,[14][15][16]30 The AIE luminogens have been reported to exhibit enhanced PL at low temperatures due to the RIR process; however, their thermoresponsive (TR) PL has not been very sensitive, reversible, or controllable. 4,[14][15][16]21,29 Among the PL stimuli-responsive hydrogels, poly(N-isopropylacrylamide) (PNIPAM) based fluorescent hydrogels have attracted much attention.…”

“…4,[14][15][16]21,29 Among the PL stimuli-responsive hydrogels, poly(N-isopropylacrylamide) (PNIPAM) based fluorescent hydrogels have attracted much attention. 1,6,9,[21][22][23]30 PNIPAM has been well acknowledged as a TR polymer, displaying a lower critical solution temperature (LCST) of 32°C in water with a reversible coil-toglobule transition. Usually, the PNIPAM-based fluorescent hydro-gels, reported from other research groups, exhibit an on−off feature during the temperature change around the PNIPAM LCST.…”

“…Usually, the PNIPAM-based fluorescent hydro-gels, reported from other research groups, exhibit an on−off feature during the temperature change around the PNIPAM LCST. 1,6,9,[21][22][23]30 An on−off PL feature imposes limits on potential applications, compared to a continuously TR PL system.…”

Side Chain Mediated Electronic Contact between a Tetrahydro‐4H‐thiopyran‐4‐ylidene‐Appended Polythiophene and CdTe Quantum Dots

“…[5][6][7][8][9][10] As inorganic constituent, nanocrystalline inorganic semiconductors (quantum dots) form an interesting class of materials because of their size-tunable photophysical properties [11][12][13][14][15][16][17] and high luminescence quantum yields. [13,14,[18][19][20][21][22] In addition, quantum dots can be relatively easily prepared by wet-chemical methods, [12,19,23,24] whereas the synthesis of bulk inorganic semiconductors often requires high temperatures or very low pressures. [25,26] Quantum dots are usually capped with a layer of organic molecules to prevent clustering of particles and to suppress nonradiative decay of excited states at the quantum dot surface.…”