Carbon dots (CDs) usually emit a strong blue light and excitation wavelength dependent long wavelength lights. This significantly limits their applications because one has to use a series of different excitation light sources to get different colors and the long wavelength emissions are usually very weak. We found that one type of CDs synthesized from p-phenylenediamine could emit various long wavelength lights (green to red) independent of the excitation wavelength when dispersed in different solvents. The photoluminescence quantum yields of the same CDs were 10–35% in different solvents for different color emissions. Based on this solvent-color effect, we further mixed the same CDs with different polymers to form solid CD films for various color emissions, and these film emissions were also excitation wavelength independent. Multicolor LEDs were demonstrated with the same CDs in solution and solid film states for color displays.
Poly(amidoamine) (PAMAM) dendrimers and hyperbranched poly(amidoamine)s are the first reported and most investigated luminescent polymers containing unconventional chromophores. The luminescence of these compounds is associated with the N-branched tertiary amine moiety, and the oxidation of the tertiary amine is assigned to the emitting source. However, in this paper, a series of novel siloxane–poly(amidoamine) (Si-PAMAM) dendrimers were synthesized by aza-Micheal reaction, and strong blue photoluminescence was observed even with the naked eye when these compounds were excited by a UV lamp. All of these compounds were not oxidated at all. Studies on the molecular structure showed that N → Si coordination bonds existed in these compounds, and those N → Si bonds caused the aggregation of carbonyl groups which show the strong luminescence.
Thermal conductivities of silicone rubber filled with ZnO in a wide volume range were measured in order to study the effect of formed conductive particle chains on thermal conductivities. With the increasing of content of ZnO particles in silicone rubber, the amount of formed conductive chains increases and the conductive chains tend linearly to increase the thermal conductivity of the composite. The experimental results obtained were also analyzed using the Nielsen and Agari models to explain the effect of ZnO filler on the formation of thermal conductive networks. Thermal conductivities of a polymer filled with high volume content of particles evidently increased with the adding of small size fillers. The scanning electron microscopy (SEM) showed that percolation threshold has been reached at 31.4 vol% ZnO filler loading, and the hybrid fillers are more densely packed than single fillers in the silicone rubber matrix. There occurs a positive temperature coefficient (PTC) phenomenon in thermal resistance in composites of silicone rubber filled with ZnO. POLYM. COMPOS., 28:125-130, 2007.
Heck coupling reactions are introduced as an efficient method to prepare porous polymers. Novel inorganic-organic hybrid porous polymers (HPPs) were constructed via Heck coupling reactions from cubic functional polyhedral oligomeric silsesquioxanes (POSS), iodinated octaphenylsilsesquioxanes (OPS) and octavinylsilsesquioxanes (OVS) using Pd(OAc)2 /PPh3 as the catalyst. Here, two iodinated OPS were used, IOPS and p-I8 OPS. IOPS was a mixture with 90% octasubstituted OPS (I8 ) and some nonasubstituted OPS (I9 ), while p-I8 OPS was a nearly pure compound with ≥99% I8 and ≥93% para-substitution. IOPS and p-I8 OPS reacted with OVS to produce the porous materials HPP-1 and HPP-2, which exhibited comparable specific surface areas with SBET of 418 ± 20 m(2) g(-1) and 382 ± 20 m(2) g(-1) , respectively, with total pore volumes of 0.28 ± 0.01 cm(3) g(-1) and 0.23 ± 0.01 cm(3) g(-1) , respectively. HPP-1 showed a broader pore size distribution and possessed a more significant contribution from the mesopores, when compared with HPP-2, thereby indicating that IOPS may induce more disorder because of the geometrical asymmetry. HPP-1 and HPP-2 possessed moderate carbon dioxide uptakes of 134 and 124 cm(3) g(-1) at 1 bar at 195 K, making them promising candidates for CO2 capture and storage. The synthesized porous polymers may be easily post-functionalized using the retained ethenylene groups.
Developing sponge materials integrating excellent flame retardancy, multitasking separation performance, and efficient emulsion-breaking ability is significant but challenging for the remediation of oil spills causing fires and environmental damages. Herein, a superhydrophobic oil-water separation sponge material, containing a melamine-formaldehyde (MF) sponge substrate, magnetic polydopamine (PDA) coating, and branched polydimethylsiloxane (PDMS) brush, through dopamine-mediated surface initiated atom transfer radical polymerization (SI-ATRP) is fabricated. The synergistic flame resistance of the MF substrate and PDMS brush significantly improves its adaptability in fire. More importantly, the decorated PDMS brushes can effectively overcome the size mismatch between sponge macropores and tiny emulsified droplets, while remaining the intrinsic macroporous characteristic. When treating W/O emulsions, the PDMS brushes stretch up to act as "interface-breaking blades" to accelerate the coalescence of emulsified water droplets. Meanwhile, such PDMS brushes can serve as "oil-trapping tentacles" to efficiently capture oil droplets when treating O/W emulsions. Such material design synergistically contributes to satisfactory separation efficiency (98.7%) and ultrahigh permeation flux (up to 1.35 × 10 5 L m −2 h −1 ), even for treating high viscosity emulsions. Besides, the reported sponge also inherits robust durability, superior recyclability, and convenient magnetic collection. These features make the sponge promising for multitasking and highly efficient oil-water separation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.