1 The term “poly(siloxyethylene glycol)” was used by us in our previous paper10 for the following polymer skeleton:
with pendant vinyl groups (PVSE) was synthesized by polycondensation of oligo(ethylene glycol) (MW = 300) and diaminodivinylsilane. PVSE300 thus obtained is soluble in cold water. The PVSE300 coupled with a polythiol compound shows properties of a negative working photoresist. A negative tone image was obtained by development with water at 4°C. PVSE300 is a new type of Si-containing polymer resist which can be developed by water. 相似文献
Repeatable topological transformation of polymers for the modulation of material functions is a challenge. We have developed a method for repeatedly resetting a cyclic macromolecular architecture to a linear architecture by photostimulation, namely, topology‐reset execution (T‐rex) based on the photochemistry of hexaarylbiimidazoles (HABIs). We synthesized cyclic poly(dimethylsiloxane)s (PDMSs) of various ring sizes with HABIs linked in the chains. UV irradiation of the cyclic PDMSs produced telechelic linear PDMSs with triphenylimidazolyl radical (TPIR) end groups. After termination of UV irradiation, end‐to‐end recyclization occurred by the recoupling of TPIRs. The cyclic PDMSs also responded to ultrasound, which decreased their molecular weight (MW) by site‐specific cleavage of in‐chain HABI moieties, and we are able to reset the MWs by subsequent phototriggered T‐rex. Furthermore, T‐rex enabled solvent‐free switching of the rheological properties of the materials while retaining the liquid character of PDMS. 相似文献
Photoelectrochemical water splitting is regarded as a promising approach to the production of hydrogen, and the development of efficient photoelectrodes is one aspect of realizing practical systems. In this work, transparent Ta3N5 photoanodes were fabricated on n‐type GaN/sapphire substrates to promote O2 evolution in tandem with a photocathode, to realize overall water splitting. Following the incorporation of an underlying GaN layer, a photocurrent of 6.3 mA cm?2 was achieved at 1.23 V vs. a reversible hydrogen electrode. The transparency of Ta3N5 to wavelengths longer than 600 nm allowed incoming solar light to be transmitted to a CuInSe2 (CIS), which absorbs up to 1100 nm. A stand‐alone tandem cell with a serially‐connected dual‐CIS unit terminated with a Pt/Ni electrode was thus constructed for H2 evolution. This tandem cell exhibited a solar‐to‐hydrogen energy conversion efficiency greater than 7 % at the initial stage of the reaction. 相似文献
Modeling approaches are presented for detecting an anomalous route to phase synchronization from time series of two interacting nonlinear oscillators. The anomalous transition is characterized by an enlargement of the mean frequency difference between the oscillators with an initial increase in the coupling strength. Although such a structure is common in a large class of coupled nonisochronous oscillators, prediction of the anomalous transition is nontrivial for experimental systems, whose dynamical properties are unknown. Two approaches are examined; one is a phase equational modeling of coupled limit cycle oscillators and the other is a nonlinear predictive modeling of coupled chaotic oscillators. Application to prototypical models such as two interacting predator-prey systems in both limit cycle and chaotic regimes demonstrates the capability of detecting the anomalous structure from only a few sets of time series. Experimental data from two coupled Chua circuits shows its applicability to real experimental system. 相似文献
We investigated the palladium-catalyzed [2?+?2?+?1] cycloaddition of aryl- and trifluoromethyl-group-substituted internal alkynes and carbon monoxide, and revealed that the PdBr2 effectively catalyzed the intended reaction. The PdBr2-catalyzed reaction smoothly proceeded and provided aryl- and trifluoromethyl-group-containing cyclopentadienone derivatives in up to 92% yield. 相似文献
The preparation of a new class of "roofed" β-iminodisulfides from sterically congested, conformationally rigid chiral 2-thiazolidinones is described. A functional survey of palladium-catalyzed asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate with dimethyl malonate proved that symmetrical "roofed" β-iminodisulfides are efficient chiral ligands, showing enantioselectivity opposite that associated with chiral "roofed" β-iminothioether ligands. 相似文献
Let A be a finite group acting on a finite group G via automorphisms. Assume that
$$(|A|,|G|)=1$$
. We prove that if
$$C_G(A)$$
is a Hall
$$\pi $$
-subgroup of G, then G has a normal
$$\pi $$
-complement. 相似文献