Fast pyrolysis of silicones at low temperatures catalyzed by anatase titanium dioxide

Huang

ACS Appl. Mater. Interfaces

et al. 2021

Self Cite

The γ radiolysis behavior of polydimethylsiloxane (PDMS) in the radiation-thermal environments (dose rate, 0.2 Gy/s) is studied to pinpoint the basic knowledge of the temperature (20–70 °C) effects. The non-monotonous temperature effects on the formation of gas products, paramagnetic species in silica, and cross-linking density are proposed to correlate with the complex chemical reaction mechanisms. Besides, molecular dynamics simulation and theoretical calculation are first performed simultaneously based on the radical chemistry and intricate material composition, making it easier to comprehend and further harness the radiolysis mechanisms and structure deterioration of PDMS. The γ radiation-induced primary gas products and dominant cross-linking phenomena are reproduced by the molecular dynamics simulations with a reactive force field, and the reaction mechanisms and physicochemical interactions among PDMS chains, gas products, reactive radicals, and silica fillers are thoroughly studied at the atomic scale. The thermochemistry of the barrierless radical coupling reactions and reactions with explicit high-barrier transition states is calculated at the M06-2X theoretical level with the 6-311g(d, p) basis set. The barrierless reactions are all exothermal with the heat release of 321–618 kJ/mol, while the potential barriers for reactions with explicit transition states vary between 37 and 229 kJ/mol. The results show that γ radiation-induced radicals are crucial for the ensuing gas formation and cross-linking reactions, especially for the radical coupling reactions. The radical chemistry involved in the radiolytic PDMS is the key to understand and simulate its radiolysis behavior, according to the experimental and simulated results.

Section: Introductionmentioning

confidence: 99%

Gamma Radiation Chemistry of Polydimethylsiloxane Foam in Radiation-Thermal Environments: Experiments and Simulations

Huang

ACS Appl. Mater. Interfaces

et al. 2021

Self Cite

“…The structures of the SCDCEs were characterized by Fourier transform infrared spectroscopy (FTIR). It can be found that the SCDCEs samples exhibit several characteristic peaks: the absorption peaks at 3350 cm −1 and 3180 cm −1 indicate the presence of N-H stretching vibration [ 22 , 23 , 24 ]; the peak at 1680 cm −1 can be attributed to the C=O stretching vibration [ 23 , 24 ]; the absorption peak at 1200 cm −1 can be assigned to the Si-O-Si bonds [ 25 ]. To verify that the methoxy groups of MEMO are cross-linked to form Si-O-Si bonds, the Raman spectrum of SCDCEs was obtained ( Figure 2 b).…”

Section: Resultsmentioning

confidence: 99%

Mechanically Robust Dual-Crosslinking Elastomer Enabled by a Facile Self-Crosslinking Approach

Huang

Jin

et al. 2022

Materials

We propose a simple but rapid strategy to fabricate self-crosslinked dual-crosslinking elastomers (SCDCEs) with high mechanical properties. The SCDCEs are synthesized through one-pot copolymerization of Butyl acrylate (BA), acrylic amide (AM), and 3-Methacryloxypropyltrimethoxysilane (MEMO). Both the amino group on AM and the methoxy group on MEMO can be self-crosslinked after polymerization to form a dual-network crosslink consisting of hydrogen bonds crosslink and Si-O-Si covalent bonds crosslink. The SCDC endow optimal elastomer with high mechanical properties (the tensile strength is 6MPa and elongation at break is 490%) as the hydrogen bonds crosslink can serve as sacrificial construction to dissipate stress energy, while covalent crosslinking networks can ensure the elasticity and strength of the material. These two networks also contribute to the recoverability of the elastomers, leading them to recover their original shape and mechanical properties after being subjected to deformation in a short time.

“…Despite a minor side reaction from the substrate (A I peak), anodic signals form one broad peak. Such a feature suggests the chemical inhomogeneity of Ti(III) species, as they should be a series of hydroxyl oligomers ( Qin et al, 2020 ). Indeed, a minor Tindall effect was found with the deposition electrolyte “solution” (or should be called “sol”), although it is stable for several hours.…”

Section: Resultsmentioning

confidence: 99%

Room Temperature Electrodeposition of Ready-to-Use TiOx for Uniform p-n Heterojunction Over Nanoarchitecture

et al. 2022

The photocathodes are essential in photoelectrochemical systems for harvesting solar energy as green fuels. However, the light-absorbing p-type semiconductor in them usually suffers from carrier recombination issues. An effective strategy to address it is fabricating the p-n heterojunction to create an interfacial electric field. However, plenty of deposition process of the n-type layer for this purpose requires either sophisticated instruments or subsequent treatments, which may damage the vulnerable p-type structure. Herein, we report a mild approach for a ready-to-use n-type layer with full functionality. Structural analyses proved the successful coating of a uniform titania layer (up to 40 nm) over Cu2O without damaging its structure. Owing to the high Ti3+ content, the layer possesses excellent charge transport ability and requires no additional annealing. The heterojunction effectively facilitates the carrier separation and positively shifts the photocurrent onset potential for 0.2 V. The Mott–Schottky plot and the impedance study reveal an enhanced carrier collection with reduced charge transfer resistances. Such a nano-heterojunction can be further loaded with the hydrogen evolution catalyst, which almost doubles the photocurrent with an extended lifetime than that of the pristine Cu2O nanoarray. This approach puts forward a potentially scalable and efficient choice for fabricating photoelectrochemical devices.