Simultaneous in-situ Construction of Hybrid Films by Photoreaction

中山大学化学院 Simultaneous in-situ Construction of Hybrid Films by Photoreaction Yuan Bo Applied Chemistry 06.6.26

中山大学化学院 CHAPTER 1 Aim of the work

Organic-inorganic Hybrid materials • “molecular level mixing” • Hard, tough, chemically stable, durable, easy toprocess • Sol-gel process • generally refers the hydrolysis and polycondensation of alkoxide precursors followed by aging and drying. • Hybrid materials containing silica • Hybrid materials containing titania • Better optical and balanced physical properties

In this study, UV curable hybrid coatings with nano-titania were prepared by the in situ method. • Triarylsulfonium salt which produces super reactive free radicalsandprotonic acid as exposed to UV irradiation has been used for simultaneous in situ construction of organic crosslinking network and nano-titania hybrid films. • The formation and morphology of the titania particles could be controlled by extending pre-exposure to moisture and retarding the free radicalphotopolymerization of acrylates.

CHAPTER2 EXPERIMENTAL

Materials • Tetrabutyl titanate ( TBT, 99% from Aldrich) • Epoxy acrylate resin (EB600, from UCB) • Hydroxyethyl methacrylate (HEMA, from Mitsubishi chemical corporation) • Triarylsulfonium hexafluoroantimonate mixture (Uvacure 1592, U1592, from UCB) • 1-Hydroxy-cyclohexyl –phenyl-ketone (Irgacure184, Ir184, from Ciba) • Diphenyl(2,4,6 trimethylbenzoyl)phosphineoxide (Runtecure 1108, TPO, from Runtec Co. Ltd.) • 2,2,6,6-Tetramethyl piperidine oxide (TEMPO) was recrystallized after obtained from Acros Chemical Corporation.

Figure 2-1 Schematic diagram for the humid cabinet and PET cell 2.1 Preparation of the hybrids • A. Instant UV-irradiation as soon as the wet film was placed into the humid cabinet. • B. Exposure to moisture in humid cabinet for 90min after UV-irradiation. • C. UV-irradiation after the wet film exposed to moisture in the cabinet for a controlled period (5, 15, 30 min, respectively) • Method A is default for the preparation of cured hybrid film unless otherwise specified.

Table 2-1 Compositions of raw material *Oraganic component was composed of epoxy acrylate, monomer, photoinitiator and Tween-80.The weight ratio resin(EB600) /monomer(HEMA) =6/4; Tween-80: 0.5% in wt

2.2 Results and discussion

Scheme 2-2 Dual effect of triarylsulfonium salt for TBT hydrolysis and acrylates polymerization 2.2.1 Synthesis of the in-situ cured hybrid films Scheme 2-1 Photogeneration of free radical and super protonic acid from triarylsulfonium salt under UV irradiation

2.2.1 Synthesis of the in-situ cured hybrid films Figure 2-1 FT-IR spectra for S5-TBT30 hybrid sample during UV irradiation (a)1700~1600 cm-1 and (b) 1250~400 cm-1

2.2.2 Morphology of the in-situ cured hybrid films Figure 2-2 SEM micrographs of hybrid films： (a) S5T1-TBT30-A2;(b) S5T1-TEM0.3-TBT30-A4; (c) S5T1-TEM0.6-TBT30-A10

2.2.2 Morphology of the in-situ cured hybrid films Figure 2-3 SEM micrographs of hybrid films： (d) S5-TBT30-A6;(e) S5-TBT30-C5 (UV for 6min); (f) S5-TBT30-C15(UV for 6min);(g) S5-TBT30-C30(UV for 6min)

2.2.3 XPS analysis of the in-situ cured hybrid films Reported BE of Ti2p for TiO2: 458.1 eV Figure 2-4 XPS spectra of Ti2p(a) in the hybrid cured films prepared by different method

2.2.4 DMA analysis of the in-situ cured hybrid films Figure 2-5 DMA scanning for the hybrid films with different moisture exposure time before UV-irradiation

2.2.5 Physical properties of the in-situ cured hybrid films Table 2-2 Physical properties of the hybrid films

The cured hybrid film was transparent with slight yellow.

2.3Conclusion Titania based hybrid films were prepared by the controlled dual photoreactions and a in-situ sol-gel reaction. Triarylsulfonium salt, was used for trigging free radical polymerization of acrylates and producing super protonic acid to drive TBT into titania nano-particle. The formation and morphology of the titania particles could be controlled by extending pre-exposure to moisture and braking the free radical photopolymerization of acrylates.

2.3Conclusion XPS analysis indicated that moisture pre-exposure was favorable for improving the titania content in the surface layer of UV-cured film. Physical properties tests showed that the hardness and flexibility of the cured hybrid film were simultaneously improved.

谢谢！！ • 衷心感谢杨建文老师、曾兆华老师与张夏虹师姐不厌其烦的耐心指导。他们认真踏实又富于创新精神的研究态度以及实事求是的为人精神对我影响甚深；在我以后的学习、研究与工作中，我将以他们为榜样不懈地努力到底！

Simultaneous in-situ Construction of Hybrid Films by Photoreaction