Printed circuit boards (PCBs) are ubiquitous in electronics and make up a substantial fraction of environmentally hazardous electronic waste when devices reach end-of-life. Their recycling is challenging due to their use of irreversibly cured thermoset epoxies in manufacturing. Here, to tackle this challenge, we present a PCB formulation using transesterification vitrimers (vPCBs) and an end-to-end fabrication process compatible with standard manufacturing ecosystems. Our cradle-to-cradle life-cycle assessment shows substantial environmental impact reduction of the vPCBs over conventional PCBs in 11 categories. We successfully manufactured functional prototypes of Internet of Things devices transmitting 2.4 GHz radio signals on vPCBs with electrical and mechanical properties meeting industry standards. Fractures and holes in vPCBs are repairable while retaining comparable performance over multiple repair cycles. We further demonstrate a non-destructive recycling process based on polymer swelling with small-molecule solvents. Unlike traditional solvolysis recycling, this swelling process does not degrade the materials. Through dynamic mechanical analysis, we find negligible catalyst loss, minimal changes in storage modulus and equivalent polymer backbone composition across multiple recycling cycles. This recycling process achieves 98% polymer recovery, 100% fibre recovery and 91% solvent recovery to create new vPCBs without performance degradation. Overall, this work paves the way for sustainability transitions in the electronics industry. Recycling of printed circuit boards (PCBs) is currently restricted by the intrinsic materials design of conventional PCBs. This work presents a vitrimer-based PCB that shows great end-of-life recyclability.

Recyclable vitrimer-based printed circuit boards for sustainable electronics

Foxtail millet husk has been used as a new source of silica for preparing copper catalysts via a sol–gel technique. X-Ray diffraction shows that silica is amorphous in the ash and catalyst I while in catalyst II it crystallizes to one of its polymorphs, β-cristobalite. Scanning electron micrographs show the particles to be well dispersed in the case of ash, but irregular and agglomerated in catalyst I and II. Transmission electron microscopy confirmed that catalyst II is a nano-composite. X-Ray fluorescence detected that the ash contains 98 % silica. The basic unit, SiO4 tethedra present in the prepared materials was discovered using IR spectroscopy. ESR observed the presence of Cu(II) in both catalyst. X-Ray photoelectron spectroscopy asserted the presence of only Cu(II) in catalyst I and both Cu(0) and Cu(II) in catalyst II. The prepared materials were utilized as catalyst in the oxidation of some tertiary amines to N-oxides, with molecular oxygen as the oxidant in methanol, under ambient conditions of temperature and pressure. The reaction was monitored online. Catalyst I shows better reactivity than II towards the oxidation reaction. High performance liquid chromatography was used to analyse the oxidation products.

Copper(II) immobilized on silica extracted from foxtail millet husk: a heterogeneous catalyst for the oxidation of tertiary amines under ambient conditions

Increased environmental awareness has necessitated the development of a simple and environmentally friendly method for metal recovery from waste printed circuit boards (WPCBs). Deep eutectic solvents (DESs) are environmentally friendly and non-aqueous lixiviants that can leach metal oxides to replace mineral acids. In this study, three choline chloride (ChCl)-based DESs were synthesized, using ethylene glycol, oxalic acid (OA), and glycolic acid (GA) as the hydrogen bond donors in the eutectic mixtures. The time-dependent leaching yields and saturated loading capacities of the DESs to typical metal oxides and Ag were evaluated. Considering the leaching performances, a simple and environmentally friendly method for metal recovery from WPCBs was established, based on two-stage DES leaching processes. The research object was the mixed metal powder collected from the mechanical processing of WPCBs. The results indicated that 90.35% of Zn, 87.47% of Pb, and 16.77% of Cu were removed from the mixed metal powder after calcination by leaching of the ChCl-GA DES and precipitation of the oxalic acid solution. When the residue was subjected to ChCl-OA DES leaching, Cu was recovered by diluting ChCl-OA DES with water. Specifically, 74.93% of Cu was separated in the form of CuC2O4·2H2O with a purity of >98 wt%. The Sn remaining in the aqueous solution was efficiently recovered by the addition of reduced Fe powder, and the recovery yield of Sn in the recovery product was 51.29%. Finally, the advantages of a simplified and environmentally friendly process framework, are highlighted by a comparison of the recovery strategy for WPCB proposed in this study with conventional pyro- and hydro-metallurgical approaches. 

Simple and environmentally friendly metal recovery from waste printed circuit boards by using deep eutectic solvents

One attractive strategy to discover more active and/or crop-selective herbicides is to make structural changes to currently registered compounds. This strategy is especially appealing for those compounds with limited herbicide resistance and whose chemistry is accompanied with transgenic tools to enable herbicide tolerance in crop plants. Bromoxynil is a photosystem II (PSII) inhibitor registered for control of broadleaf weeds in several agronomic and specialty crops. Recently at the University of Tennessee—Knoxville several analogues of bromoxynil were synthesized including a previously synthesized pyridine (2,6-dibromo-5-hydroxypyridine-2-carbonitrile sodium salt), a novel pyrimidine (4,6-dibromo-5-hydroxypyrimidine-2-carbonitrile sodium salt), and a novel pyridine N-oxide (2,6-dibromo-1-oxidopyridin-1-ium-4-carbonitrile). These new analogues of bromoxynil were also evaluated for their herbicidal activity on soybean (Glycine max), cotton (Gossypium hirsutum), redroot pigweed (Amaranthus retroflexus), ve...

Synthesis and evaluation of heterocyclic analogues of bromoxynil.

Development of banana fabric incorporated polymer composites for printed circuit board application

Due to the ever-increasing amount of electronic waste (e-waste) worldwide, the problem of the effective disposal of printed circuit board waste (WPCB), which are environmentally hazardous, difficult to recycle and economically valuable products, has become a major environmental challenge. Conventional WPCB recycling techniques have low efficiency and require tough processing, such as heat treatment and high pressure. This paper presents a new composite material for the manufacture of printed circuit boards (PCB) that can be easily recycled into their original components and reused. In addition, the most valuable PCB components (electronic components containing precious metals) can be easily separated from the printed circuit board and reused. This study demonstrates the benefit of using biodegradable polymers as binders for PCBs in terms of environmentally friendly and efficient recycling. 

/pdf/a-new-approach-to-designing-easily-recyclable-printed-3npf5isw.pdf

A new approach to designing easily recyclable printed circuit boards

Oxidation of heterocycles of the pyridine series under conditions of microwave irradiation was studied. It is established that oxidation of pyridine and 4-methylpyridine with hydrogen peroxide results in the corresponding N-oxides, and oxidation of 3-(piperidin-2-yl)pyridine gives δ-oximino-δ-(pyridyl-3-N-oxide)-valeric acid.

Microwave Activation in the Synthesis of Nitrogen Heterocycles, N-Oxides of Pyridine Series

Synthesis of some 1,4-dihydropyridines under the microwave irradiation

2-Substituted-1,3-oxazolidines still remain actively studied nitrogen-containing heterocycles due to their effective application in medicine, agriculture, and polymer and paint and varnish industry [1 2]. Among fairly few synthetic approaches to 1,3-oxazolidines, heterocyclization heterocyclization of vicinal aminoalcohols with various aldehydes and ketones occupies a special place. Depending on the activity of the starting reagents, the reaction time varies from 4 to 12 h. The yields of the target products are 65 95% [3 5].

Synthesis of 2-substituted-1,3-oxazolidines under microwave irradiation

An efficient method for the synthesis of 1,4-dihydropyridine derivatives in a flow microwave reactor

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

D. P. Khrustalev

Author Tools

Chat about Author