6 research outputs found
Mixed carbon nanomaterial/epoxy resin for electrically conductive adhesives
The increasing complexity of printed circuit boards (PCBs) due to miniaturization, increased the density of electronic components, and demanding thermal management during the assembly triggered the research of innovative solder pastes and electrically conductive adhesives (ECAs). Current commercial ECAs are typically based on epoxy matrices with a high load (>60%) of silver particles, generally in the form of microflakes. The present work reports the production of ECAs based on epoxy/carbon nanomaterials using carbon nanotubes (single and multi-walled) and exfoliated graphite, as well as hybrid compositions, within a range of concentrations. The composites were tested for morphology (dispersion of the conductive nanomaterials), electrical and thermal conductivity, rheological characteristics and deposition on a test PCB. Finally, the ECAâs shelf life was assessed by mixing all the components and conductive nanomaterials, and evaluating the cure of the resin before and after freezing for a time range up to nine months. The ECAs produced could be stored at â18 °C without affecting the cure reaction.This research was funded by the Portugal Incentive System for Research and Technological Development,Project in Co-Promotion nâŠ039479/2019 (Factory of the Future: Smart Manufacturing 2019â202
Nanofluid Based on GlucoseâDerived Carbon Dots Functionalized with [Bmim]Cl for the Next Generation of Smart Windows
The design of new advanced materials and technologies is essential for the development of smart windows for the next generation of energyâefficient buildings. Here, it is demonstrated that the functionalization of glucoseâderived carbon dots with 1âbutylâ3âmethylimidazolium chloride results in a selfâstanding, waterâsoluble, viscous, reusable nanofluid with selfâimproving conductivity, thermotropy around 30â40 °C, and ultraviolet blocking ability. Its synthesis is straightforward, clean, fast, and cheap. At 36 °C (hot summer day), a sunâactuated thermotropic (TT) device incorporating a 95% w/w nanofluid aqueous solution exhibits a transmittance variation (ÎT ) of 9% at 550/1000 nm, which is amplified to 47/31% via the surface plasmon resonance effect. An integrated selfâhealing system enabling independent sunâactuated TT and voltageâactuated electrochromic (EC) operation is also produced. The lowâenergy EC device offers bright hot and dark cold modes (ÎT = 68/64%), excellent cycling stability, unprecedented coloration efficiency values (â1.73 Ă 106/â1.67 Ă 106 cm2 Câ1 (coloring) and +1.12 Ă 107/+1.08 Ă 107 cm2 Câ1 (bleaching) at ±2.5 V), and impressive memory effect. The disruptive design and sustainable synthesis of the new nanofluid proposed here will foster the agile development of novel products with improved ecological footprint.This research was funded by the National Funds by Foundation for Science and Technology (FCT) and by the FEDER funds through POCI-COMPETE 2020-Operational Programme Competitiveness and Internationalization in Axis I: Strengthening research, technological development and innovation (UID/QUI/00616/2013, UID/QUI/50006/2019, UID/Multi/00709/2013, UID/QUI/00313/2019, UID/CTM/50025, POCI-01-0145-FEDER-007491, POCI-01-0145-FEDER-007688, UID/CTM/50025, POCI-01-0145-FEDER-016884, PTDC/CTM-NAN/0956/2014, SAICT/PAC/0032/2015, POCI-01-0145-FEDER-016422, and NORTE-01-0145-FEDER-030858). R.F.P.P. acknowledges FCT-MCTES for SFRH/BPD/87759/2012 grant. R. Rego and M. Fernandes (UTAD, Vila Real) and E. Pereira (FCUP, Porto) are acknowledged for their assistance.info:eu-repo/semantics/publishedVersio
Functionalization of Poly(ethylene terephthalate) Fibers by Photografting of a Carbohydrate Derivatized with a Phenyl Azide Group
Layer-by-layer assembly of graphene oxide and 12-molybdosilicate composite films for the electrocatalytic reduction of chloroform in neutral aqueous solution
Non-Newtonian Thermosensitive Nanofluid Based on Carbon Dots Functionalized with Ionic Liquids
Non-Newtonian nanofluids present outstanding features in terms of energy transfer and conductivity with high application in numerous areas. In this work, non-Newtonian nanofluids based on carbon dots (Cdots) functionalized with ionic liquids (ILs) are developed. The nanofluids are produced using a simple, single-step method where the raw materials for the Cdots synthesis are glucose and waste biomass (chitin from crab shells). The use of ILs as both reaction media and functionalization molecules allows for the development of a new class of nanofluids, where the ILs on the Cdots surface represent the base-fluid. Here, the well-known benign IL 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) and a novel home-made IL (1-tosylate-3-methyl-imidazolium triflate) [Tmi][Trif] are used. The nanofluids obtained from both substrates show, apart from high conductivity and viscosity, light absorption, and good wettability, an appealing thermal sensitivity behavior. This thermal sensitivity is preserved even when applied as thin films on glass slides and can be boosted using the surface plasmon resonance effect. The results reported demonstrate that the new Cdots/IL-based nanofluids constitute a versatile and cost-effective route for achieving high-performance thermosensitive non-Newtonian sustainable nanofluids with tremendous potential for the energy coatings sector and heat transfer film systems