High-efficiency pentafluorostilbene-based photocatalysts dedicated to preparing fluorescent 3D printed polymer nanocomposites

Figures & data

Figure 1. Structures of investigated pentafluorostilbene derivatives.

Figure 2. 3D printing models employed for DLP technology: (a) study of the resolution of the prepared resins, (b) DMA measurements, (c) TGA measurements.

Figure 3. Absorption spectra of 1,2,3,4,5- pentafluoro-6-[(E)-styryl]benzene derivatives.

Table 1. Spectroscopic characterisation of 1,2,3,4,5-pentafluoro-6-[(E)-styryl]benzene derivatives.

Acronym	λmax-ab*[nm]	ϵ @λmax-ab*	ϵ@λ365nm	ϵ@λ405nm	ϵ@λ420
M1	293	19958	200	62	51
M2	365	9203	9203	3356	1159
M3	362	2397	2290	304	92
M4	362	27920	27502	3814	587
M5	368	2191	2179	567	217
M6	368	2265	1738	319	65
M7	366	24023	24014	5395	1078
M8	375	2587	2558	1217	555
M9	375	1695	1637	400	107
M10	375	28569	27021	11298	3078

λ_max-ab*[nm] – The wavelength corresponding to the absorption maximum for the longest wavelength band [nm]. ϵ _@λmax-ab* – molar extinction coefficient at λ_max-ab.

Table 2. Electrochemical and thermodynamic properties of 1,2,3,4,5-pentafluoro-6-[(E)-styryl]benzene derivatives.

Sample	Eox [mV]	E00 [eV]	ΔGet [eV]	Ered [mV]	KSV [M^−1]	Φet(S1)	τS1 [ns]	ket [M^−1s^−1]
M1	1771	3.72	−1.31	−1838	-	-	-	-
M2	1068	2.82	−1.11	−1820	40.09	0.46	2.10	1.91·10^9
M3	1029	2.94	−1.27	−1825	49.49	0.51	3.47	1.43·10^9
M4	957	2.93	−1.33	−1883	70.45	0.60	0.57	1.24·10^10
M5	1089	3.05	−1.32	−1805	27.29	0.36	0.38	7.18·10^9
M6	1043	3.18	−1.50	−1843	42.00	0.47	2.35	1.79·10^9
M7	921	3.02	−1.46	−1883	32.15	0.40	0.56	5.74·10^9
M8	1101	2.79	−1.05	−1790	77.69	0.62	8.72	8.91·10^8
M9	1053	2.97	−1.28	−1830	109.71	0.70	5.51	1.99·10^9
M10	976	2.83	−1.21	−1833	52.00	0.52	3.36	1.55·10^9

E_ox – Photosensitiser oxidation potential [mV]; Ag/AgCl reference electrode; E₀₀ – Singlet state energy of the photosensitiser determined from excitation and emission spectra; ΔG_et – Gibbs free energy [eV]; E_red – Photosensitiser reduction potential [mV]; K_SV – Stern–Volmer coefficient [M⁻¹]; Φ_et(S1) – electron transfer quantum yields in the singlet excited state; τ_(S1) – lifetime of the excited state of the sensitiser [ns]; k_et – electron transfer rate constant [M⁻¹s⁻¹]; Electrochemical measurements carried out in 0.1M solution of tetrabutylammonium hexafluorophosphate in acetonitrile; Ag/AgCl reference electrode; Pt working electrode, ‘-’ not calculated.

Figure 4. FT-IR spectrum changes for CADE epoxy monomer-based composition during cationic photopolymerisation under 365 nm UV-LED irradiation, employing IOD + M10 (1.0/0.1% w/w) initiator system.

Figure 5. Kinetic profiles obtained during the cationic photopolymerisation of the epoxy monomer CADE for two-component systems consisted of the IOD iodonium salt and the appropriate 1,2,3,4,5-pentafluoro-6-[(E)-styryl]benzene derivative (1.0/0.1% w/w) during irradiation with a UV-LED emitting a wavelength of 365 nm.

Table 3. The obtained conversion rates of CADE epoxy monomer during the cationic photopolymerisation process applying light sources in the UV-Vis range.

Acronym	ϵ@λ365nm	C@λ365nm	ϵ@λ405nm	C@λ405nm	ϵ@λ420	C@λ420nm
M1	200	np	62	np	51	-
M2	9203	46	3356	42	1159	-
M3	2290	47	304	45	92	-
M4	27502	45	3814	48	587	-
M5	2179	48	567	11	217	-
M6	1738	47	319	30	65	-
M7	24014	48	5395	34	1078	-
M8	2558	41	1217	34	555	-
M9	1637	54	400	42	107	-
M10	27021	59	11298	51	3078	47

ϵ – molar coefficient of extinction [dm³mol⁻¹cm⁻¹]; C – Conversion of epoxy groups monitored at ∼790 cm⁻¹ [%]; ‘-’ – no polymerisation

Table 4. The obtained values of induction time and kinetic curve slope during the process of cationic photopolymerisation initiated by UV- and Vis-LED light sources.

Acronym	dC/dt (@λ365nm)	t (@λ365nm)	dC/dt (@λ405nm)	t (@λ405nm)	dC/dt (@λ420nm)	t (@λ420nm)
M1	-	-	-	-	-	-
M2	0.36	9.46	0.22	21.75	-	-
M3	0.28	24.19	0.16	57.18	-	-
M4	0.69	1.84	0.39	6.08	-	-
M5	0.20	34.36	0.47	4.46	-	-
M6	0.21	26.35	0.06	83.91	-	-
M7	0.64	1.09	0.21	16.07	-	-
M8	0.12	47.84	0.09	64.11	-	-
M9	0.40	15.32	0.11	74.44	-	-
M10	0.42	7.71	0.71	1.46	0.23	6.36

t – induction time [s]; dC/dt – slope of the kinetic curve [s⁻¹]; ‘-’ no polymerisation

Figure 6. Effect of the amine group character present in the photosensitiser structure on the degree of CADE monomer conversion (light source LED@365 nm).

Figure 7. Influence of the substitution location of the amino group in the photosensitiser on the conversion rate of the CADE monomer (light source LED@365 nm).

Figure 8. Photosensitisers exhibiting the highest photocatalytic activity.

Figure 9. Changes in the FT-IR spectrum for an acrylate monomer-based TMPTA composition during radical photopolymerisation under 365 nm UV-LED irradiation, employing the IOD + M10 (1/0.1% w/w) initiator system.

Figure 10. Kinetic profiles achieved during the progress of radical photopolymerisation of acrylate monomer TMPTA for two-component systems consisting of the IOD iodonium salt and the corresponding 1,2,3,4,5-pentafluoro-6-[(E)-styryl]benzene derivative (1.0/0.1% w/w) during irradiation with a UV-LED emitting a wavelength of 365 nm.

Table 5. The obtained conversion rates of acrylate monomer TMPTA, the values of the induction time and the slope of the kinetic curve during the progress of radical photopolymerisation initiated by UV- and Vis-LED light sources.

Acronym	ϵ@λ365nm	C@λ365nm	dC/dt (@λ365nm)	t (@λ365nm)	ϵ@λ405nm	C@λ405nm	dC/dt (@λ405nm)	t (@λ365nm)
M1	200	10	0.03	26.25	62	-	-	-
M2	9203	35	0.13	3.76	3356	13	0.10	2.83
M3	2290	30	0.20	10.28	304	32	0.37	4.82
M4	27502	23	0.27	18.62	3814	23	0.29	17.73
M5	2179	20	0.08	18.51	567	20	0.08	18.91
M6	1738	36	0.40	5.82	319	15	0.18	2.07
M7	24014	21	0.31	18.42	5395	8	0.15	2.35
M8	2558	15	0.09	6.43	1217	33	0.35	16.31
M9	1637	38	0.37	29.72	400	28	0.11	22.06
M10	27021	44	0.94	9.66	11298	44	1.56	1.24

ϵ – molar coefficient of extinction [dm³mol⁻¹cm⁻¹]; C – Conversion of acrylate group monitored at ∼1634 cm⁻¹ [%]; dC/dt – slope of the kinetic curve [s⁻¹]; t – induction time [s]; ‘-’ no polymerisation

Figure 11. Changes in the FT-IR spectrum for resins based on CADE epoxy monomer and TMPTA acrylate monomer during hybrid photopolymerisation under 365 nm UV-LED irradiation using IOD + M9 (1.0/0.1% w/w) initiator system.

Figure 12. Kinetic profiles obtained during the photopolymerisation process of the hybrid acrylate monomer TMPTA and the epoxy monomer CADE for the two-component system consisting of the iodonium salt IOD/M10 (1.0/0.1% w/w) during irradiation with a UV-LED emitting a wavelength of 365 nm.

Table 6. The obtained conversion rates of acrylate monomer TMPTA and epoxy monomer CADE during the progress of hybrid photopolymerisation initiated by UV-LED light source.

	AIR		LAMINATE
Acronym	C@λ365nm ∼790 cm^−1	C@λ365nm ∼1634 cm^−1	C@λ365nm ∼790 cm^−1	C@λ365nm ∼1634 cm^−1
M1	-	-	11	13
M2	70	22	30	46
M3	80	40	22	74
M4	70	17	18	54
M5	77	57	22	51
M6	71	40	21	73
M7	63	12	20	63
M8	77	44	27	66
M9	75	40	17	75
M10	72	15	24	74

C – Conversion of epoxy group monitored at ∼790 cm⁻¹ / of acrylate group monitored at ∼1634 cm⁻¹ [%]; ‘-’ no polymerisation

Table 7. Formulation of photo-curable polymerising resins by radical mechanism.

	Monomer formulation [%]			Initiating system
Resin 1	Ebecryl 4858	Ebecryl 130	Photomer 4012	IOD	M10
	70	15	15	1%	0.10%
Resin 2	Ebecryl 4740	Ebecryl 130	Photomer 4012
	70	15	15
Resin 3	Ebecryl 4858	Ebecryl 45	Photomer 4012
	70	15	15
Resin 4	Ebecryl 4740	Ebecryl 45	Photomer 4012
	70	15	15
Resin 5	Ebecryl 1291	Ebecryl 130	Photomer 4012
	70	15	15
Resin 6	Ebecryl 1291	Ebecryl 45	Photomer 4012
	70	15	15

Figure 13. Determination of printing characteristics for radical resins (1-6).

Table 8. 3D printing conditions and determined parameters for resins 1–6.

Formulation	Equation	Critical energy [mJ/cm^2]	Light penetration depth [µm]	Light intensity [mW/cm^2]	3D printer power [%]
Resin 1	y = 336.29ln(x) – 1693.20	153.69	326.38	7.96	80
Resin 2	y = 270.87ln(x) – 1293.50	118.55	267.76
Resin 3	y = 303.86ln(x) – 1510.30	144.08	302.14
Resin 4	y = 301.75ln(x) – 1488.70	138.87	299.91
Resin 5	y = 316.37ln(x) – 1674.70	199.04	316.39	9.95	100
Resin 6	y = 264.55ln(x) – 1377.80	182.74	263.41

Table 9. Formulation of radical resins 2a–2e.

Resin 2
	Monomers (w/w/w)			Initiating system (w/w)
	Ebecryl 4740	Ebecryl 130	Photomer 4012	IOD	M10
(a)	70%	15%	15%	1%	0.1%
(b)					0.3%
(c)					0.5%
(d)					0.8%
(e)					1.0%

Figure 14. Kinetic profiles achieved during radical photopolymerisation of 2a-2e resins applying LED@405 nm light source.

Table 10. The obtained conversion rates of acrylate monomers, the values of the induction time and the slope of the kinetic curve during the progress of hybrid photopolymerisation initiated by Vis-LED light source (LED@405 nm).

	Resin 2
	M10 [%]	C [%]	dC/dt	t [s]
(a)	0.10	77.70	0.44	22.70
(b)	0.30	76.15	0.24	23.80
(c)	0.50	76.76	0.16	25.90
(d)	0.80	73.30	0.15	31.20
(e)	1.00	72.14	0.12	33.30

C – conversion of acrylate groups ∼6165 cm⁻¹ [%]; dC/dt – slope of the kinetic curve [s⁻¹]; t – induction time [s]

Table 11. Formulation of radical resin 2a and resin 7.

Resin 2
	Monomers (w/w/w)			Initiating system (w/w)		ZnO (w/w)
	Ebecryl 4740	Ebecryl 130	Photomer 4012	IOD	M10
Resin 2a	70%	15%	15%	1%	0.1%	-
Resin 7						10%

Figure 15. Determination of printing characteristics for resin 2 and resin 7.

Table 12. 3D printing conditions and determined parameters for resins 2 and 7 (resin 2 + 10% ZnO).

Formulation	Equation	Critical energy [mJ/cm^2]	Light penetration depth [µm]	Light intensity [mW/cm^2]	3D printer power [%]
Resin 2	y = 270.87ln(x) – 1293.50	118.55	267.76	7.96	80
Resin 7	y = 169.71ln(x) – 709.90	65.56	170.63

Figure 16. Photographs of the print obtained with resin 2 using DLP technology; images taken on an optical microscope and camera; images taken under visible light and with a UV flashlight.

Figure 17. Photographs of the print obtained with resin 7 using DLP technology; images taken on an optical microscope and camera; images taken under visible light and with a UV flashlight.

Figure 18. Photographs of a print obtained with resin 2 using DLP technology; images obtained on a scanning electron microscope.

Figure 19. Photographs of a print obtained with resin 7 using DLP technology; images obtained on a scanning electron microscope.

Figure 20. SEM-EDS analysis of (a) the resin 2 print, (b) the resin 7 print.

Figure 21. Dynamical mechanical analysis (DMA) analysis showing storage and loss moduli, and loss factor as a function of temperature for resin 2 (without nanoparticles) and resin 7 (with nanoparticles).

Table 13. 3D printing conditions and determined parameters for resins 1–7. Glassy at −25, rubbery at +120.

Formulation	Tg [°C]	E’glassy [GPa]	E’ruberry [MPa]	T at failure [°C]	υe [kmol·m^−3]
Resin 1	61.7	3.91	38.3	>160	35.2
Resin 2	50.3	2.84	52.8	>160	48.5
Resin 3	55.1	3.83	43.9	>160	40.3
Resin 4	50.2	2.78	68.0	>160	62.4
Resin 5	64.4	3.81	116.5	123	106.9
Resin 6	63.4	3.70	129.7	122	119.0
Resin 7	44.5	2.91	44.9	>160	41.2

Figure 22. Thermogravimetric analysis (TGA) and differential thermogravimetric analysis (DTGA) show the relative weight change and its derivative with temperature up to 700°C.

Data availability statement

The data that support the findings of this study are openly available in Mendeley Data at https://data.mendeley.com/datasets/52m89r83df/1.