Preparation and characterization of 3-chloropropyl polysiloxane-based heat-curable silicone rubber using polyamidoamine dendrimers as cross-linkers

Facile Preparation of Polysiloxane-Modified Asphalt Binder Exhibiting Enhanced Performance

The development of polymer-modified asphalt (asphalt = asphalt binder) is significant because the polymer modifier can improve the performance of asphalt mixture and meet the requirements of the modern asphalt pavement. Herein, we present a novel polysiloxane-modified asphalt with enhanced performance, formed by simply mixing hydroxy-terminated polysiloxane (HO-PDMS) into base asphalt at 140 °C. The interaction mechanism of HO-PDMS in base asphalt was characterized by FT-IR, GPC, and DSC. It reveals that HO-PDMS polymers have been chemically bonded into the asphalt, and, thus, the resultant asphalt exhibits optimal compatibility and storage stability. The results based on fluorescence microscopy and a segregation test prove that HO-PDMS has good compatibility with base asphalt. Moreover, by virtue of the intriguing properties of polysiloxane, the present asphalt possesses improved low- and high-temperature properties, higher thermal stability, and enhanced hydrophobicity compared to conventional asphalt when using an appropriate dosage of HO-PDMS. DSC indicated that the Tg of modified asphalt (-12.8 °C) was obviously lower than that of base asphalt (-7.1 °C). DSR shows that the rutting parameter of modified asphalt was obviously higher than that of base asphalt. BBR shows that modified asphalt exhibited the lowest stiffness modulus and the highest creep rate with an HO-PDMS dosage of 6% and 4%, respectively. These results demonstrate that polysiloxane-modified asphalt can be promisingly utilized in realistic asphalt pavement with specific requirements, particularly high-/low-temperature resistance.

Self-Healing Coating with a Controllable Release of Corrosion Inhibitors by Using Multifunctional Zinc Oxide Quantum Dots as Valves

As an intelligent response system, self-healing anticorrosion materials containing nanocontainers have aroused increasing demands. It is highly expected that the nanocontainers can rapidly respond on corrosion signals to efficiently release corrosion inhibitors, meanwhile to avoid an undesirable leakage before the local corrosion happening. Herein, zinc oxide quantum dot (ZnO-QD)-sealed hollow mesoporous TiO₂ nanocontainers loading with 14.2% benzotriazole (BTA) inhibitor have been successfully prepared [hollow mesoporous titanium dioxide nanospheres (HMTNs)-BTA@ZnO-QDs]. ZnO-QDs play the multifunctional roles on anticorrosion of the self-healing coating. The corrosion tests of coatings on the carbon steel well demonstrate that ZnO-QDs can not only act as a valve to seal and release BTA on the time but also act as a precursor to produce the protective film of Zn(OH)₂ by the reaction of Zn²⁺ ions with OH^- around the cathode region to inhibit the corrosion of carbon steel. After being soaked in 3.5% NaCl solution for 30 days, the |Z|_0.01 Hz value of the coating with HMTNs-BTA@ZnO-QDs still maintains at 2.87 × 10⁷ Ω cm². Once the defects are formed in the coating, the acid-responsive ZnO-QD valves are rapidly decomposed to release BTA inhibitor; meanwhile, the resulted Zn(OH)₂ layer prevent the carbon steel substrate from corrosion in the cathode area. Therefore, it could be promising that the present design of the nanocontainers matching with the multifunctional ZnO-QDs can offer a valuable strategy to construct the self-healing and anticorrosion coatings with a multiresponse to the corrosion environment.

One Stone for Multiple Birds: A Versatile Cross-Linked Poly(dimethyl siloxane) Binder Boosts Cycling Life and Rate Capability of an NCM 523 Cathode at 4.6 V

Increasing working voltage is a promising way to increase the energy density of lithium-ion batteries. Cycling and rate performance deteriorated due to excessive electrolyte decomposition and uncontrolled formation of a cathode-electrolyte interface (CEI) layer at a high voltage. A new concept is proposed to construct a high-voltage-stable electrode-electrolyte interface. An elastomeric poly(dimethyl siloxane) (PDMS) binder is incorporated into the electrode to modify the LiNi_0.5Co_0.2Mn_0.3O₂ (NCM 523) particle surface via an in situ cross-linking reaction between hydroxy-terminated PDMS and methyl trimethoxy silane promoted by moisture at ambient conditions (MPDMS). Improved electrochemical performance is achieved with the MPDMS binder in terms of reversible capacity (201 vs 185 mAh·g^-1 at 0.2C), capacity retention (80 vs 68%, after 300 cycles at 1C), and rate performance (55.6% increase at 5C), as demonstrated by the NCM 523||Li half-cell. The NCM 523||graphite full-cell also shows improved performance at 4.6 V (147 vs 128 mAh·g^-1, 82 vs 76%, after 200 cycles at 1C). The mechanism studies indicate that MPDMS exerts multiple effects, including cathode surface passivation, solvation structure tuning, electrolyte uptake enhancement, and mechanical stress relief. This work provides an inspiring route to realize high-voltage application of lithium-ion battery technology.

Theoretical Investigation of the Hydrolytic Mechanism of α-Functionalized Alkoxysilanes as Effective Crosslinkers and the Difficulty of Deep Vulcanization in RTV Silicone Rubber

The reactions between α-, γ-ethylenediaminemethyl trimethyl-ketoxime silane (α-, γ-EAMOS) and H₂O were investigated on the geometries of stationary points, the reaction pathway (IRC), thermodynamic and kinetic analysis by density functional theory (DFT) at the B3LYP/6-311G (d, p) level. Interestingly, the results showed that the hydrolysis activity of α-EAMOS is higher than that of γ-EAMOS, due to the influence of an amino substituent in position α-C on silicon. α-EAMOS can be used as a superior crosslinker for room temperature vulcanized (RTV) silicone rubber to achieve rapid crosslinking without a toxic catalyst. Besides, compared with the reaction between α-EAMOS and H₂O, the reactivity between α-EAMOS and hydroxy siloxane (HO⁻Si(CH₃)₂⁻OSiH₃) was discussed. Particularly, it revealed that the deep vulcanization of RTV silicone rubber is difficult.

Impacts of Different Functional Groups on the Kinetic Rates of α-Amine Ketoximesilanes Hydrolysis in the Preparation of Room Temperature Vulcanized Silicone Rubber

α-Amine ketoximesilanes are proven to be effective crosslinkers in the preparation of ketone-oxime one-component room temperature vulcanized (RTV) silicone rubber without the use of toxic metal catalyst. This work aimed to investigate the hydrolysis kinetic of α-amine ketoximesilanes, which is vitally important for the preparation of RTV silicone rubber. Five kinds of α-amine ketoximesilanes, namely α-(N,N-diethyl)aminomethyltri(methylethylketoxime)silane (DEMOS), α-(N,N-di-n-butyl)aminomethyltri(methylethylketoxime)silane (DBMOS), α-(N-n-butyl)aminomethyltri(methylethylketoxime)silane (n-BMOS), α-(N-cyclohexyl)aminomethyltri(methylethylketoxime)silane (CMOS) and α-(β-aminomethyl)aminomethyltri(methylethylketoxime)silane (AEMOS), were successfully obtained and confirmed using Fourier transform infrared spectrometer (FT-IR) and hydrogen-1 nuclear magnetic resonance ( ¹H NMR). Kinetics of hydrolysis reactions were measured by FT-IR and conductivity. Our results illustrated that the kinetic constant rates ranged from 12.2 × 10^−4 s^−1 to 7.6 × 10^−4 s^−1, with the decreasing order of DEMOS > n-BMOS > DBMOS > CMOS > AEMOS at the given temperature and humidity. Better performances of thermal stability could be achieved when using the α-amine ketoximesilanes as crosslinkers in the preparation of RTV silicon rubber than that of RTV silicone rubber with the use of methyltri(methylethylketoxime)silane (MOS) as a crosslinker and organic tin as a catalyst.

Preparation and characterization of silicone rubber cured via catalyst-free aza-Michael reaction

A novel silicone rubber of high strength and stable dimension was cured via catalyst-free aza-Michael reaction.

Preparation and characterization of room temperature vulcanized silicone rubber using α-amine ketoximesilanes as auto-catalyzed cross-linkers

A series of α-amine ketoximesilanes were prepared and used as auto-catalyzed cross-linkers in one component room temperature vulcanized (RTV) silicone rubber.