In this study, photoinitiated cationic polymerization of epoxy resins by photoinduced electron transfer reactions using four new chromophoric dyes, namely (3E)-1,1′-bis(2-ethylhexyl)-6,6′-dipyren-1-yl-3,3′-biindole-2,2′(1H,1′H)-dione (ISOIV), (3′E)-1,1′′′-diethyl-1′,1′′-bis(2-ethylhexyl)-1H,1′′′H-5,6′:3′,3′′:6′′,5′′′-quaterindole-2′,2′′(1′H,1′′H)-dione (ISOV), (3E)-6,6′-bis(9-ethyl-9H-carbazole-3-yl)-1-[(2R)-2-ethylhexyl]-1′-[(2S)-2-ethylhexyl]-3,3′-biindole-2,2′(1H,1′H)-dione (ISOVIII) and 3,3′-(6-bromokinoksalin-2,3-diyl)bis(9-ethyl-9H-carbazole) (TPDC6), and diphenyliodonium hexafluorophosphate (Ph2I+PF6−; DPI) under sunlight is reported. Upon irradiation, photoexcited dye forms an exciplex with DPI. Electron transfer reactions within the exciplex result in the formation of ionic species capable of initiating ring-opening polymerization of an epoxy resin. It is shown that among the investigated dyes, ISOVIII and TPDC6 exhibited higher initiation efficiency in accordance with their stronger electron-donating nature due to the presence of carbazole groups. © 2021 Society of Industrial Chemistry. 

Highly conjugated isoindigo and quinoxaline dyes as sunlight photosensitizers for onium salt‐photoinitiated cationic polymerization of epoxy resins

In both organic and polymer synthesis, photochemistry of Charge Transfer Complexes (CTCs) is considered as a powerful approach to expand visible-light-driven radical chemistry reaction. We report herein on the development of a class of useful CTCs using pyridinium salts as efficient electron acceptors (combined with N, N, 3, 5-tetramethylaniline, TMA) to achieve a multi-wavelength (375-560 nm) metal-free LED photopolymerization process under mild conditions (open to air, without monomer purification and inhibitor removal). The UV-vis absorption spectra and molecular modeling simultaneously verified its potential blue-green absorbing wavelength range. Also, their good thermal initiation behavior at relatively low temperature makes it easier to achieve thick samples and/or polymerization in the shadow region in practice. More importantly, with excellent photoinitiating capability, the formulation was successfully applied to direct laser write (DLW) and high-resolution 3D printing, yielding series of objects with well-defined structures, such as letters, ring, solid square and chess piece. These new pyridinium salt acceptors further extend the applicability to visible photopolymerizable resins and additive-containing formulations for efficient surface and deep curing. This article is protected by copyright. All rights reserved.

Charge Transfer Complexes (CTCs) with Pyridinium Salts: Towards Efficient Dual Photochemical/Thermal Initiators and 3D Printing Applications.

The photopolymerization synergistic thermal polymerization process has been successfully applied in the preparation of very opaque composites. In this work, the fabrication of opaque few layer graphene (FLG) composites was...

Enhanced dual photo/thermal initiating systems for preparation of few layer graphene filler-based composites and 3D printing

In this work, the effect of the side group of a series of silane coupling agents, as well as the subsequent anchoring of an imidazole derivative, for TiO2 particles, within the polypropylene polymeric matrix, with emphasis on their mechanical properties and their crystallization kinetics, and their rate of degradation. Differences were the following: the 3-Glicydoxypropyltrimethoxysilane was the best in photostability overall. On the other hand, 3-Chloropropyltrimethoxysilane promoted the degradation. All the other silane coupling agents avoided the anatase's photocatalytic activity, inhibiting the polymer matrix's degradation. 

Study of the photodegradation of polypropylene: Effect of the silane coupling agents as organosilicon coatings in TiO2 fillers, evaluation of the thermomechanical properties.

This article presents, for the first time, the efficacy and curing depth analysis of photo-thermal dual polymerization in metal (Fe) polymer composites for 3D printing of a 3-component (A/B/M) system based on the proposed mechanism of our group, in which the co initiators A and B are Irgacure-369, and charge-transfer complexes (CTC), respectively; and the monomer M is TMPTA filled by Fe. Our formulas show the depth of curing (Zc) is an increasing function of the light intensity, but a decreasing function of the Fe and photoinitiator concentrations. Zc is enhanced by the additive [B] which produces extra thermal radical for polymerization under high temperature. The heat (or temperature) increase in the system has two components : (i) due to the light absorption of Fe filler, and (ii) heat released from the exothermic photopolymerization of the monomer. The heat is transported to the additive (or co-initiator) [B] to produce extra radical R' and enhance the monomer conversion function (CF). The CF has two opposite trends in their time profiles: (i) for small Fe concentration (F), it is a time decaying function; and (ii) for large Fe, it is a time increasing profile. This switching feature predicted by our formula is also justified by our measured data. The Fe filler leads to temperature increase, but also limits the light penetration leading to lower CF and Zc, which could be overcome by the additive initiator [B] in thick polymers. the new finding of optimal Fe for maximal CF and Zc are explored theoretically. 

Modeling the Enhanced-Efficacy and Curing-Depth of Photo-Thermal Dual Polymerization in Metal (Fe) Polymer Composites for 3D Printing

Imidazole based dual photo/thermal initiators for highly efficient radical polymerization under air with a metal-free approach

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.

Qiang Ma

Author Tools

Chat about Author

Papers

Imidazole based dual photo/thermal initiators for highly efficient radical polymerization under air with a metal-free approach