IMAGING SCIENCE AND PHOTOCHEMISTRY

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2019, 37(5): 0-0.

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The Perparation and Application of Crosslinkable Fluorine-containing Particles via Photopolymerization in Supercritical Carbon Dioxide

LI Xingzhou, HOU Zunyan, HE Yong

2019, 37(5): 392-401. DOI: 10.7517/issn.1674-0475.190610

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Two kinds of fluorinated oligomers containing acrylate double bonds in side chains were prepared by two-step method of free radical random copolymerization and acylation. A series of polyfunctional oligomers with different double bond content and fluorine content were prepared by adjusting the kinds of reactants, ratio and the dosage of chain transfer agent. The prepared fluorine-containing oligomer was used as a raw material to carry out photopolymerization granulation in supercritical carbon dioxide. The fluorine-containing particles obtained by polymerization are added as a reinforcing phase to the TPGDA photocurable formulation to achieve chemical crosslinking of the particles and the resin, which significantly increases the crosslinking density of the substrate, improves hydrophobicity, reduces water absorption and enhances thermal stability.

The Synthesis and Properties of UV-LED Sensitive Coumarin-carbazole-based Oxalate Photoinitiators

ZHOU Ruchun, LIU Yizhuo, CHEN Shixiong, WANG Weijie, CHEN Siqi, JIN Ming

2019, 37(5): 402-414. DOI: 10.7517/issn.1674-0475.190613

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In this paper, two coumarin-carbazole based oxalate photoinitiators (2-OAME and 4-OAME) were designed and synthesized. By introducing the coumarin into carbazole group, the π-conjugated structure is enlarged, resulting to the good absorption properties in UV-visible light range. The photophysical and photochemical properties were characterized by UV-Vis absorption spectra and FT-RTIR. The two photoinitiators exhibit excellent light absorption properties in the near UV-Vis range and have good photoinitiated polymerization ability under excitation by the LED light source. The 4-OAME molecule exhibited better photoinitiated polymerization ability under the same conditions than 2-OAME. The two photoinitiators have great application potential in the field of near-ultraviolet-visible LED photopolymerization.

Synthesis and Structure-activity Relationship of Coumarin-based Oxime-esters as Two-photon Photoinitiators

LI Mengqi, QIU Wanwan, HU Peng, ZHU Junzhe, LIU Ren, LI Zhiquan

2019, 37(5): 415-427. DOI: 10.7517/issn.1674-0475.190603

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Development of efficient two-photon initiators (2PIs) are critical to promote two-photon 3D printing speeds. On the basis of photodecarboxylation, two unimolecular 2PIs that contain coumarin moieties (as two-photon absorption chromophores) and oxime-ester groups (as initiation functional groups) were synthesized. The investigation of the photophysical and photochemical behaviors of the oxime-esters were conducted via quantum-chemical calculations and experimental tests. The results indicated that the 2PIs exhibits a broad absorption band ranging from 400 to 500 nm. Under visible LED light irradiation, the investigated oxime-esters decomposed and formed active free radicals to effectively induce polymerization of acrylates. Interestingly, the photoinitiators exhibit a good photobleaching property. In two-photon polymerization tests with acrylate formulations, the oxime-ester derivatives can be used to build complex 3D microstructures with high spatial resolution. The possible photopolymerization mechanism was proposed according to the quantum chemical calculation results.

Effect of Monomers Structures on Properties of Self-healing Photocured Materials Based on Ion Interaction

HAN Jiwei, GONG Haoran, YUE Dewei, JIANG Shengling, SUN Fang

2019, 37(5): 428-437. DOI: 10.7517/issn.1674-0475.190602

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In this paper, the effects of soft and hard monomer structures and their proportions on photopolymerization behaviour, and mechanical and self-healable properties of self-healing photocured materials were investigated. The results show that changing the structures and proportions of hard and soft monomers did not change the photopolymerization behaviour of the photocurable self-healing system. Increasing the content of the soft monomer and decreasing the content of the hard monomer can increase the tensile strain and healing efficiency of materials, and decrease the tensile stress. The rigid rings of the hard monomer can increase the internal friction between the polymer chains, thereby increasing the tensile stress of the materials, while the soft monomer containing flexible ether chains can reduce the van der Waals force between the chains and enhance the chain mobility, thereby improving the tensile strain and healing efficiency of the materials. Sample IB7-BA3 with butyl acrylate (BA) and isobornyl acrylate (IBOA) shows good comprehensive performance and its tensile stress, tensile strain and healing efficiency are 1.42 MPa, 295% and over 90%, respectively.

Preparation and Properties of New Photoinitiator for UV-LED Photo Source

PANG Yulian, ZHAO Liying, GAO Ming, ZOU Yingquan

2019, 37(5): 438-444. DOI: 10.7517/issn.1674-0475.190707

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One photoinitiator based on the 3,4-ethylenedioxythiophene (EDOT) was synthesized through introducing an acetylehienyl and an acetyl group respectively into two active sites of the EDOT. The structure was characterized by ¹HNMR spectroscopy. UV-Vis absorption spectroscopy, thermal stability were also tested. We also measured its photoinitiating activity with real-time FTIR technology. The results show that the photoinitiator has good absorption in the range of 365-405 nm, which is better than 2-isopropylthioxanthone(ITX) and suitable for UV-LED photocuring systems. Meanwhile, its thermal stability is better than ITX and the photoinitiating activity is comparable to ITX.

Synthesis and Photopolymerization of Benzophenone Macromolecular Photoinitiators

HAO Yajuan, LI Jingfang, LI Dongbing, YANG Jinliang, NIE Jun

2019, 37(5): 445-455. DOI: 10.7517/issn.1674-0475.190710

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Two macromolecular photoinitiators PPI 1 and PPI 2 were synthesized and characterized. The results showed that the UV absorption behavior of PPI 1 and PPI 2 are similar to that of 4-BP, the molar extinction coefficient are higher,the rate of photodegradation are faster. Without the addition of EDAB,compared to PPI 1 and PPI 2, as the molecular weight (functionality) of photoinitiator increased, the polymerization rate increased and the final double bond conversion rate of HDDA increased. The extraction amount of film cured by PPI 1 was 44.5% than that of 4-BP,PPI 2 was 40% than that of 4-BP respectively,after immersed in CH₂Cl₂ solution for 5 days.

Synthesis of Mercapto-based MTQ Resin and Its Effect on Photocuring Properties of Acrylate System

LIU Tongzheng, WANG Yong, XUE Tanlong, WANG Tao

2019, 37(5): 456-464. DOI: 10.7517/issn.1674-0475.190520

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The mercapto-based MTQ resin(SH-MTQ) was synthesized by hydrolysis copolymerization of hexamethyldisiloxane, γ-(methacryloyloxy)propyltrimethoxysilane and tetraethyl orthosilicate under acidic conditions. The obtained resin was analyzed by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy (¹HNMR), gel permeation chromatography and thermogravimetry. The effect of mercapto-based MTQ resin on the photocuring of TPGDA was investigated by using 1-hydroxycyclohexyl phenyl ketone (184) as a photoinitiator. It was found that the addition of mercapto-based MTQ resin increased the photocuring rate and double bond conversion rate of TPGDA, and the properties of cured film hardness, thermal stability, transmittance and contact angle also increased.

Research Progress of POSS-containing Photoresist Materials

YOU Fengjuan, HAN Jun, YAN Chenfeng, WANG Liyuan

2019, 37(5): 465-472. DOI: 10.7517/issn.1674-0475.190605

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Photoresists are the key materials for micro-pattern processing. Polyhedral oligomeric silsesquioxane (POSS) is a kind of reinforcement material for polymer with regular cage structure. The polymer modified by POSS realizes organic-inorganic nano-hybridization. The introduction of rigid structure of POSS hinders the movement of polymer molecules, and so significantly increases the glass transition temperature (T_g), reduces the dielectric constant and improves the mechanical properties of the polymers. The etch resistance of POSS-containing photoresists is also enhanced. Based on these advantages, POSS-containing photoresist materials have attracted extensive attention. The research progress on POSS-containing photoresists is briefly introduced.

Photo-curing 3D Printing and Its Application in Dental Field

LUO Shen, XU Hang, ZHANG Ting, QUAN Haoyuan, ZHU Xiaoqun

2019, 37(5): 473-484. DOI: 10.7517/issn.1674-0475.190527

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The first 3D printing machine which was based on the photo-curing technology was invented in the 1988. After more than 30 years of development, photo-curing 3D printing has the technology of SLA, DLP, LCD, CLIP, two-photon polymerization, holographic 3D printing technology and so on. Due to the character of high resolution, fast printing speed, photo-curing 3D printing technology has been widely applicated in several fields. Among these applications, the application of photo-curing 3D printing in the dental field is the most potential and highest value-added. The dental field has a distinctive and very individual character. At the same time, the dental field requires the printing sample with high resolution, which matches with the photo-curing 3D printing perfectly. In this article, the type, principle and the advantages and disadvantages of the photo-curing 3d printing were introduced and its application in dental field was also described briefly.

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