UV Light Effect on Cationic Photopolymerization of the SU8 Photoresist and Its Composites with Carbon Nanotubes: New Evidence Shown by Photoluminescence Studies

Abstract

The effect of UV light on the cationic photopolymerization of the SU8 negative photoresist is shown by photoluminescence (PL) studies. Our results demonstrate that the cationic photopolymerization reaction of the SU8 photoresist takes place predominantly under the influence of the UVA light. Using UVA light, the influence of carbon nanotubes [of the types single-walled carbon nanotubes (SWNTs), double-walled carbon nanotubes (DWNTs), multiwalled carbon nanotubes (MWNTs), and SWNTs functionalized with carboxyl groups (SWNTs-COOH)] on the cationic photopolymerization process of the SU8 photoresist is shown by PL studies. The cationic photopolymerization of the SU8 photoresist is monitored by the variations of the two emission bands with maxima at ∼400−429 nm and 523−556 nm. The increase in the relative intensity of the PL band at ∼523− 556 nm is dependent on (i) the carbon nanotube concentration in the SU8 photoresist matrix; (ii) the type of carbon nanotubes, i.e., SWNTs, DWNTs, and MWNTs; and (iii) the nonfunctionalized and functionalized state of SWNTs. The results reported in this work demonstrate that PL can be used as a complementary method to Raman scattering and IR spectroscopy in the investigation of the cationic photopolymerization reaction of the SU8 negative photoresist. A decrease in the wrapping angle of carbon nanotubes with the SU8 photoresist is highlighted by anisotropic PL studies.

The Photoluminescence and Vibrational Properties of Black Phosphorous Sheets Chemically/Electrochemically Functionalized in the Presence of Diphenylamine

“…The main Raman lines observed in Figure 5 a–c have maxima at ~415–498 cm −1 , 621–825 cm −1 , 906–1003 cm −1 , 1184 cm −1 , 1331 cm −1 , 1367 cm −1 , 1497 cm −1 , 1581 cm −1 and 1614 cm −1 , belonging to macromolecular compound of DPA, i.e., PDPA doped with PTA heteropolyanions. These Raman lines are attributed to the vibrational modes caused by the deformation of the benzene ring, out-of-side of the benzene plane, P-O in the PO 4 structures of the heteropolyanion, of C-H bond in the benzene ring, C aromatic ring - N in the radical cation type structural units N, N′-diphenyl benzidine, C-C stretching in the benzene ring + C-H bond in the benzene ring, C=N stretching, C=C stretching in the quinoid ring and C-C stretching in the benzene ring, respectively [ 37 , 38 , 39 , 40 ].…”

“…In our case, the variation of the Raman line attributed to the A 1g vibrational mode from 362 cm −1 to 378 cm −1 can be explained by taking into account the compression of the layers containing P atoms, which is induced by PDPA. In Figure 6 d, it can be seen that the IR spectrum of PDPA doped with the PTA heteropolyanions is characterized by the IR bands having maxima at 696 cm −1 , 748 cm −1 , 812 cm −1 , 874 cm −1 , 922 cm −1 , 1022 cm −1 , 1074 cm −1 , 1176 cm −1 , 1315 cm −1 , 1454 cm −1 , 1499 cm −1 and 1595 cm −1 , attributed to the vibrational modes of the inter-ring deformation, ring deformation, W-O c -W (O c corresponds to oxygen from the corner of the heteropolyanion structure), W-O e -W (O e corresponds to oxygen from the side of the heteropolyanion structure), W=O, the deformation of the quinoid ring, the stretching of the P-O-W bond, the C-H bond in the benzene (B) ring, C aromatic - N, the stretching of the C=N + C-H bond in the benzene ring, the stretching of the C-C bond in the benzene (B) ring + the stretching vibration of the C=C bond in the quinoid ring (Q) and the stretching of the C=C bond in the -NH + =Q=Q=NH + - structure, respectively [ 37 , 38 , 39 ].…”

Anisotropic Photoluminescence of Poly(3-hexyl thiophene) and Their Composites with Single-Walled Carbon Nanotubes Highly Separated in Metallic and Semiconducting Tubes

“…Thus, the r values in the case of the solution of P3HT, P3HT/S-SWNTs and P3HT/M-SWNTs were equal to 0.045, 0.018 and 0.037. The θ PL values of P3HT in the absence and in the presence of S-SWNTs and M-SWNTs between the macromolecular compound adsorption and emission dipoles were calculated with the relation r = 0.4[(3cos 2 θ PL − 1)/2] [ 28 , 29 ], these being equal to 50.2°, 52.9° and 51.2°, respectively.…”

Photoinduced ring-opening polymerizations

“…Among works reported about RICFP, epoXy composite materials containing ZrO2 and SiO2 nanopowders, kaolin clay, and carbon fibers have been carried out and the possibility to UV-crosslink glass fibers reinforced epoXy composite has been demonstrated for the first time [355][356][357][358][359]. Very recently, the integration of carbon nanotubes in a matriX based on the commercial SU-8 epoXy photoresist have allowed obtaining composite materials under UV-A irradiation [360].…”