Cationic Photopolymerization Initiated by a Photocatalytic Complex Sensitive to Visible Light at 520 nm
- PDF / 1,534,681 Bytes
- 10 Pages / 595.276 x 790.866 pts Page_size
- 32 Downloads / 175 Views
Cationic Photopolymerization Initiated by a Photocatalytic Complex Sensitive to Visible Light at 520 nm Yulan Zhou1 · Wanfeng Liao1 · Xiuyuan Ni1 Received: 14 September 2020 / Accepted: 19 October 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract For the cationic photopolymerization of high value, we designed a new visible-light initiator complex consisting of the visible-light sensitive titanium dioxide ( Pyx%:TiO2, x = 3, 6, 9, 12), octanioc acid and iodonium salt (Iod). The ternary complex was proved to efficiently initiate the cationic ring-opening polymerization of the epoxide under the light irradiation at the wavelength of 520 nm. By using gas chromatography-mass spectra (GC-MS), electron spin resonance (ESR) and 1 H-nuclear magnetic resonance (1H-NMR), the mechanism studies clearly presented that the Pyx%:TiO2 photocatalyzed the oxidation reaction of octanioc acid in the pathway of photo-Kolbe decarboxylation. Meanwhile, Iod was decomposed by the photocatalytic reduction reaction. The results of this visible-light photocatalytic cationic polymerization process were analyzed by using attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy and gel permeation chromatography (GPC). The conversion of the epoxide can reach up to 93.8%. Graphic Abstract
Keywords Photopolymerization · Visible-light sensitive · Photocatalytic initiator complex · Photocatalytic decarboxylation reaction · Cationic ring-opening polymerization Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10562-020-03437-z) contains supplementary material, which is available to authorized users. Extended author information available on the last page of the article
13
Vol.:(0123456789)
1 Introduction The reaction routes of photopolymerizations are divided into the free radical reaction for the polymerization of alkenes and the cationic reaction for ring-opening polymerization [1]. The cationic polymerization usually produces high performance materials with good modulus and tensile strength and takes the advantage of low oxygen inhibition [2, 3]. The cationic polymerization has been broadly used in the integrated circuits, dental materials and photoresists [4, 5]. For instance, in the cationic photopolymerization of epoxides, the epoxide is activated by the photoinitiator through the oxygen atom at the epoxy ring being protonated, followed by the ring-opening reaction [6]. The nucleophilic attack by other epoxides gives rise to a propagating chain with an active chain end. Besides the curing of epoxides, photochemical synthesis of the engineering plastics and biomedical materials, such as polyesters [7] and 2-oxazoline [8], has been recently developed by using the ring-opening polymerization. Currently, the commercialized photoinitiators are only sensitive to UV light [9]. Serving as a kind of classic cationic initiators, iodonium salts (Iod) such as diphenyliodonium hexafluorophosphate, absorb UV light at the wavelength shorter than 3
Data Loading...
