Synthesis of resveratrol/POSS-based polymethacrylates and their
Applications in Fluorescent Anti-counterfeiting and DLP3D Printing
Keywords:Resveratrol, MA-POSS, UV click, fluorescent material, DLP3D printing
Abstract:
In order to meet the requirements of green, environmentally friendly, safe, and sustainable resins for digital light processing (DLP) 3D printing, as well as to enhance the comprehensive performance of the photosensitive resin methacrylate, this paper synthesized a trifunctional methacrylate monomer (REM) from the biomass resveratrol, and improved the performance of the REM/ POSS composites by adding different mass fractions (10%, 20%, 30%, and 50%) of MA- POSS to improve the properties of REM/POSS composites, a series of light-cured biomaterials (REM/POSS) were prepared by using an efficient UV click reaction, and the thermomechanical properties, mechanical properties, dielectric properties, and transparency of REM/POSS were investigated The results showed that the addition of MA-POSS resulted in a significant enhancement of the thermal stability of the REM/POSS composites, which was reflected in the enhancement of T5 %, T10 %, and End mass. Due to the cage-like nanopore structure of MA-POSS, the dielectric constant of the REM/POSS-30% composites presents a good advantage in the high-frequency range (DK value of 2.90 at 14.2 GHz). In addition, the thermal stability as well as the mechanical properties of REM/POSS-0% were superior to those of MEP/POSS-0% (MEP: commercial resin, bisphenol A-type difunctional methacrylate resin). Due to the resveratrol's diphenylethylene structure, QR codes prepared with MEP/POSS-20% resin show strong blue fluorescence under UV light, whereby they can be used for information storage and encryption. The successful printing of the "pyramid" proves that REM/POSS composite resins are suitable for DLP3D printing. Thus, REM/POSS composite resins may offer an alternative to petroleum-based materials as a sustainable and functional resin.
Introduction
Additive manufacturing, also known as 3D printing, is a disruptive manufacturing technology of great significance. Because of its unique advantages in manufacturing complex geometric parts, it is now used in various fields such as aerospace, medical engineering, consumer products, etc. 3D printing technology mainly includes digital light processing (DLP)[1, 2] 3D printing technologies mainly include digital light processing (DLP) and stereolithography (SLA).[3] DLP uses a digital micromirror device to create objects with complex geometries faster than SLA.DLP uses a light-curing polymer as the precursor material, which is irradiated with ultraviolet light, and the free radical-induced hierarchical photopolymerization leads to the successive construction of the liquid resin in the z-direction (longitudinal axis).[4] . It stands out among many 3D printing technologies because of its ability to produce high-precision 3D objects quickly, and the fine feature structure control makes DLP technology increasingly popular for industrial applications. Light-curing resins used for 3D printing are mainly divided into acrylate resins and epoxy resins[5] , Among them, methacrylate resins contain photoinitiators and photoactive monomers/crosslinkers, and the system can undergo efficient free radical polymerization under UV light irradiation.
However, most photosensitizing resins are made from expensive and unsustainable petroleum-based[6] However, most photosensitive resins are made from expensive and unsustainable petroleum, and some of these resins pose a safety risk to human health. For example, bisphenol A (BPA)-based acrylate resins are widely used in manufacturing and life and are successfully utilized in 3D printing[7, 8] However, numerous studies have shown that BPA has adverse effects on human reproduction and development, neural networks, cardiovascular, metabolic and immune systems.[9] The impact of BPA on the human reproductive and developmental, neural network, cardiovascular, metabolic and immune systems has been shown in numerous studies. In addition, the increasing popularity of optical 3D printing poses an environmental problem for society in terms of the difficulty of recycling used products.[10] This state of affairs places higher demands on the biosafety of polymers.
As a result, researchers are urgently searching for biomass materials that can replace petroleum-based biomass sources[11] to meet the need for environmentally friendly materials in materials science and chemistry, as well as to respond to the national call for "carbon peaking and carbon neutrality".[12] and in response to the national call for "carbon peaking and carbon neutrality". For the synthesis of sustainable materials, resveratrol[13] is a favored raw material. On the one hand, it is a natural polyphenol compound widely found in grape skins, red wine and some other fruits, with antioxidant, anti-inflammatory and cardiovascular properties. On the other hand, resveratrol has three highly reactive phenolic hydroxyl groups, which are easily involved in chemical reactions and can be used in the synthesis of acrylate resins[14, 15] Resveratrol has three highly active phenolic hydroxyl groups. Resveratrol contains a stilbene structure, which shows strong blue fluorescence under ultraviolet light irradiation[16, 17] Chen[18] et al. prepared a nanogel based on resveratrol triacrylate, which can clearly observe blue fluorescence under 310 nm UV light irradiation, and accordingly can be used for cellular imaging of human breast cancer cells.
However, methacrylate-based resins typically exhibit unsatisfactory dielectric properties, inadequate thermal stability and brittleness. [19] . To meet the needs of the printed electronics industry[20] and high-performance composites[21] many advanced fields, it is important to enhance the dielectric properties of acrylate resins. Polyhedral oligosilsesquioxane (POSS)[22] is a conformationally precise nanomolecule with a molecular diameter range of 1-3 nm, consisting of an inorganic core Si-O-Si cage structure and organic "arms" R (organic or inorganic functional groups) surrounding the inorganic core. Due to the large free volume of the POSS nanoparticles, the high porosity, the low molecular polarizability, and the rigidity of the internal inorganic cage structure, composites containing POSS are often characterized by a large free volume, high porosity, low molecular polarization, and a rigid internal inorganic cage structure. POSS-containing composites usually have low dielectric constants, stable mechanical properties, excellent thermal stability, and good compatibility. [23] Li et al[24] successfully synthesized benzoxazinyl polyhedral oligomeric sesquicarbazone (BZ-POSS) and used it to modify bisphenol A-type epoxy resin nanocomposites, and the dielectric constant was reduced to 2.28 at 1 MHz when BZ-POSS was added at 20%.
In this paper, the trifunctional methacrylate-terminated epoxide monomer REM was successfully synthesized from resveratrol feedstock, and the chemical structures of RE and REM were characterized using nuclear magnetic resonance (NMR) hydrogen spectroscopy, carbon spectroscopy (1 H NMR13 C NMR), high-resolution mass spectrometry (HRMS), and Fourier transform infrared spectroscopy (FT-IR) Hydroxypropyl methacrylate caged oligosilsesquioxane (MA-POSS) was introduced into the REM matrix as a reactive monomer, and hydroxyethyl methacrylate was used as a diluent to prepare the REM/POSS composites using UV click reaction. In addition, the bio-based resin (REM/POSS-0%) was combined with the bisphenol A propanetriol bis(methacrylate) (MEP/POSS-0%) for a comparative study. Heat loss analysis (TGA), tensile testing and dielectric constant measurements were used to evaluate the thermal stability, mechanical and dielectric properties of the composites. Finally, QR codes and "HZUN" letters were prepared using the REM/POSS-20% resin, and a composite resin was developed for digital light processing DLP printing technology. REM/POSS composites have potential as new luminescent materials for anti-counterfeiting applications due to their blue fluorescence under UV light and excellent overall performance. The REM/POSS composite material has the potential to be used as a new luminescent material in the anti-counterfeiting field due to its blue fluorescence under UV light and its excellent comprehensive performance, and it also provides a new resin with environmental friendly and high dielectric properties for DLP3D printing.
2.1 Materials
Bisphenol A-type resin (MEP, i.e., bisphenol A malonyl bis(methacrylate)) as well as resveratrol were purchased from Anegi Chemicals. Sodium hydroxide, epichlorohydrin, and methacrylic acid were from Sinopharm Chemical Reagent Co. Triphenylphosphine (TPP) and methylhydroquinone (THQ) were obtained from Aladdin. Hydroxyethyl methacrylate (HEMA) and (2,4,6-trimethylbenzoyl)diphenylphosphine oxide (TPO) were purchased from Bide Pharmaceuticals.MA-POSS was purchased from Changsha Baxi Instrument Co.
2.2 Syntheses of RE and REM
In a 250 ml round bottom flask, resveratrol (21.9 mmol) and epichlorohydrin (438.0 mmol) were added, equipped with a magnetic stirrer and reflux condenser, and the temperature was raised to 90°C. After the temperature was raised to 90°C, sodium hydroxide (65.7 mmol), which had been fully dissolved in 48 ml of ethanol, was added dropwise to the reaction system. The entire reaction was carried out under nitrogen atmosphere (Scheme 1). The completion of the reaction was monitored by thin layer chromatography and the resulting products were separated by column chromatography. The RE obtained was a white solid in 85% yield.
The synthesized RE (7.6 mmol) was taken in a 100 ml three-necked flask, TPP (1.0% by mass of solids) was added as catalyst, THQ (0.2% by mass of solids) was added as cross-linking inhibitor, methacrylic acid (34.1 mmol) was added under nitrogen atmosphere, equipped with a magnetic stirrer and a reflux condenser, and the reaction was heated up to 105°C for 4 hours (Scheme 1). After the reaction, the product was dissolved in dichloromethane and washed three times with hot 10 wt% NaCl solution, dried over anhydrous sodium sulfate, evaporated under reduced pressure and placed in a vacuum oven to remove the solvent, resulting in a clear, viscous liquid with 90% REM yield.
2.3 Sample preparation of REM/POSS composites
79.9 wt% MEP, 20 wt% HEMA, and 0.1 wt% TPO were stirred well and introduced into the mold, and then cured under UV light for 10 min, and this sample was named MEP/POSS-0%. Under the same conditions, MEP was replaced with REM and the sample was named REM/POSS-0%. To this, different mass percentages of MA-POSS (10 wt%, 20 wt%, 30 wt% and 50 wt%) were added. The percentages were sequentially named REM/POSS-10%, REM/POSS-20%, REM/POSS-30%, and REM/POSS-50%, all of which are the ratio of the total mass of the mixture (Table 1).
A resin for a DLP3D printer (model: ANYCUBIC Photon Ultra) comprised 10wt% REM,10wt% MA-POSS,75%wt HEMA,5wt% TPO. Specifically, the resin was introduced into the sample chamber and exposed to a UV light source at a wavelength of 405 nm, and each layer was cured for a duration of 8 s, with a layer thickness of about 0.05 mm. After printing was completed, the sample was removed from the holder, and washed with ethanol to remove residual chemicals such as the surface inhibited by oxygen from unreacted resin.
Table 1. Different compositions of photocurable resin consist of, REM, REP, MA-POSS, HEMA and TPO. All the compositions were prepared in % (w/w).
Scheme 1. (A) Synthetic route for preparing (RE) and (REM), (B) The structural formula of MEP. (C) UV curing route of REM/POSS composites.
2.4 Instrumental Methods
1. Nuclear magnetic resonance spectrometer (NMR)
The chemical structures of RE and REM were tested by1 H-NMR,13 C-NMR using a nuclear magnetic resonance spectrometer (model: BrukerAvance 400) with the frequency set to 400 MHz. All tests were dissolved with CDCl3 containing an internal standard, which was tetramethylsilane (TMS). 2、Fourier infrared spectroscopy (FT-IR)
The chemical structures of RE and REM were qualitatively analyzed by FT-IR spectrometer (model: Nicolet 7000 Antaris), and the test wavelength range was 4000-600 cm-1 .
3. Plastic-Film Tensile Properties Test Methods
An electronic type tensile testing machine (Model: AI-7000M) was used to test the mechanical properties of the composite resin samples. Specifically, the tensile test was conducted in accordance with GB/T 13022-91 with a tensile rate of 10 mm/min. all mechanical tests were conducted at least five times to determine the average performance and associated errors. 4、Scanning electron microscope
A scanning electron microscope (model: Zeiss Sigma 500) was used to observe the fracture morphology of the silicone resin samples after brittle fracture by liquid nitrogen.
5、Thermogravimetric analyzer
A thermogravimetric analyzer (Model: Nerzsch TG 209 F1) was used to test the thermal stability of composite resins, N2 atmosphere, with a set temperature range of room temperature to 800°C, and a temperature increase rate of 10°C/min. 6、 Shore hardness tester
Shore hardness tester (Model: HS-A) was used to test the hardness of samples with a thickness of 0.64mm. Collect the hardness value of three and more points and calculate the average value. Finally the Shore A hardness is converted to convert to Shore D hardness (D=A-50).
7, using the material dielectric constant and shielding effectiveness test system (Model: E5063A Coaxial Prober-2 test samples (thickness of 0.64mm) of the dielectric constant and dielectric loss. Measure 5 times, discard the maximum value and minimum value, and take the average value.
9. Thermo Scientific HAAKE MARS rheometer
Viscosity was tested at 25°C over a range of shear rates from 0.1 to 600s−1 .
10, PHOTON ULTRA 3D printer (Model: PHCTCN ULTRA) for composite resin printing.
3. Results and discussion
3.1 Synthesis and characterizations of RE and REM
Fig. 1. (A)1 H NMR spectra of RE, (B)1 H NMR spectra of REM, (C) FT-IR of RE (red line) and REM (blue line).
The reaction of resveratrol with epichlorohydrin under alkaline conditions gave RE. The phenolic hydroxyl group of resveratrol was located at around 9-10 ppm, once the reaction took place, the epoxide functionalities of H4,5 , H2 , and H1,3 appeared at 4.25-3.96, 3.34, and 2.74-2.97 ppm, respectively (Fig. 1(A)), which indicated the complete glycidylation of resveratrol, and the chemical shifts of the endo-olefins, i.e., H8 and H11 , were located at 6.99 and 6.90 ppm, respectively. shifts were located at 6.99 and 6.90 ppm, respectively.The chemical shifts of all the protons in the REM after the reaction of RE with methacrylic acid are shown in Fig. 1(B). The results show that the chemical shifts of Ha -He corresponding to REM are essentially unchanged compared to those of H6 -H10 for RE. Hk and Hl are located at 5.62 and 6.16 ppm, respectively, which correspond to two different chemical environments on the double bond of methacrylate, and the single peak of Hm at 1.96 ppm corresponds to the methyl group of methacrylate, and the hydroxyl peak at 2.77 ppm corresponds to the hydroxyl peak (Hn ), and the peaks of H at 3.96- The proton peak at 4.38 ppm originates from the alkyl group between the ester and ether bonds (Hf -Hj ).
The FT-IR spectra of RE and REM are shown in (Fig. 1(C)). The C-H stretching vibration in the endo-olefin is located at 3008 cm−1 , while the C-C stretching vibration overlaps with that of the aryl ring, and the absorption at 968 cm−1 confirms the E conformation of RE. On the other hand, the oxocycloalkane moiety usually has peaks at 856, 910 and 1257 cm−1 due to the asymmetric and symmetric bending vibrations of the hydrocarbons. The peaks for ether bonds in the oxirane moiety appear at 1034 and 1069 cm−1 and the strong absorption at 1170 cm−1 belongs to the aryl ether functional group.RE exhibits typical aromatic-C=C vibrational absorption at 1510 and 1630 cm−1 . Upon reaction with methacrylic acid, the intensity of the peak at 3400 cm−1 was significantly enhanced, corresponding to the stretching vibration of -OH in REM. 1740 cm−1 and 1630 cm−1 corresponded to the C=O and -C=C stretching vibration peaks, respectively, while the characteristic absorption peaks of -C-O-C (alkyl epoxide) at 856, 910, and 1257 cm−1 almost disappeared. These results were consistent with the conversion of epoxy end-groups to methacrylate, and the FT-IR,1 H NMR, and13 C NMR (Figure S1) results clearly confirmed the successful synthesis of REM, while the molecular mass of REM was further determined to be 654.2693 using high resolution mass spectrometry (ESI-MS) (Figure S2).
3.2. Curing behavior of MEP Composites and different REM/POSS Composites
Fig. 2 (A). Corresponding FT-IR spectra after UV-Curing. (B). Corresponding optical transmittance spectra after UV-Curing.
The cured composites were characterized by FT-IR (Fig. 2(A)), and the increase in POSS content led to an increase in the intensity of the absorption peak of the ester carbonyl group (C=O) at 1740 cm−1 , the tensile vibrational absorption peak of the silicon-oxygen bond (Si-O-Si) appeared at 1037 cm−1 , and the tensile vibrational absorption peak of the carbon-carbon double bond (C=C) at 1630 cm−1 weakened significantly after curing, but a small amount of C=C remained and gradually enhanced with the increase of MA-POSS. However, a small amount of C=C is still retained, and the absorption peaks gradually increase with the increase of MA-POSS, which is mainly due to the retention of the rigid stilbene structure of REM and the rigid cage structure of MA-POSS that restricts the chain movement to a certain extent.[25] REM is a trifunctional methacrylate monomer with a planar structure and rigid resveratrol units, and when the conversion reaches a certain level, the propagating chain and the remaining C=C bonds are restricted by many bulky branched chains connected with resveratrol units, which hinders the reaction and prevents the conversion from increasing.[15] .. The multiple double bonds and rigid structure allow the preservation of the stilbene structure, which still shows blue fluorescence under UV irradiation after curing. In addition, the REM/POSS composites had high transparency (Fig. 2(B)), with UV transmittance as high as 88% for REM/POSS-50% and 85% for REM/POSS-0%, which showed a decreasing trend with the increase of POSS mass fraction, which was attributed to the yellowing phenomenon of the acrylate-based resins after curing.
3.3. Thermal property of MEP Composites and REM/POSS Composites.
Fig. 3.TGA of MEP Composites and different REM/POSS Composites.
Table 2. Thermal stability of MEP Composites and REM/POSS Composites.
Fig. 3 shows the thermogravimetric analysis (TGA) of REM/POSS with pure commercial resin, pure bio-based resin, and different MA-POSS contents, and the data collection is shown in Table 2. The results show that the thermal stability of REM/POSS-0% is better than that of MEP/POSS-0%, which is reflected in the fact that there is no significant difference in the initial decomposition temperature (T5 %), and that REM/POSS-0%'s T10 %, and Tp % are better than that of MEP/POSS-0%. The End mass of REM/POSS-0% (22.0%) was 15.6% higher than that of MEP/POSS-0% (6.6%) at 328.7 °C, 425.7 °C and 800 °C, respectively. This was attributed to the inherent rigid stilbene structure of resveratrol, and the trifunctional methacrylate structure resulted in a higher crosslink density of the polymer. Based on this, the incorporation of rigid MA-POSS also greatly enhances the thermal stability. It can be observed that the T5 % and T10 % of the polymers are significantly enhanced with the increase of MA-POSS content from 10% to 50%, and the End mass increases incrementally with the increase of MA-POSS content, reaching 36.9% when the addition amount is 50%, which is 14.9% higher than that of REM/POSS-0% and 30.3% higher than that of MEP/POSS-0%. This is mainly due to the fact that more heat is required to break the stabilized Si-O-Si bonds in POSS. In addition, POSS introduces nanopores in the crosslinked network, which reduces the thermal conductivity of the composite resin and increases the initial decomposition temperature.POSS can form stable and heat-resistant silica particles by polycondensation at high temperatures, which makes the residual amount increase with the increase of POSS content[26] POSS.
3.4. Mechanical property of MEP Composites and REM/POSS Composites.
Tensile tests were performed on the pure commercial and REM/POSS composite resins, and the results are shown in Fig. 4(A), which shows that the mechanical properties of the pure resveratrol-based resins were significantly better than those of the commercial type.The tensile strength of REM/POSS-0% (57.3 MPa) was 7.0 MPa higher than that of MEP/POSS-0% (50.3 MPa).The fracture elongation (22.9%) was 14.7% higher than that of MEP/POSS-0% (8.2%). The mechanical properties of the REM/POSS composites showed a decreasing and then increasing trend as the addition content of MA-POSS increased from 10% to 50%, and the tensile strength and elongation at break were gradually balanced. Figure 4(B) shows that the Shore hardness D are all in the range of 47-50, and the Shore hardness of MEP/POSS-0% is higher than that of REM/POSS-0%, and the hardness also tends to decrease firstly and then increase with the incorporation of MA-POSS.The excellent mechanical properties of the REM/POSS composites are mainly attributed to the tri-functional methacrylate structure provided by REM, which offers high cross-linking density for the cured The excellent mechanical properties of REM/POSS composites are mainly due to the trifunctional methacrylate structure provided by REM, which provides a high cross-linking density for the cured resin, and the methacrylate groups of active MA-POSS and the diluent hydroxyethyl methacrylate can participate in the cross-linking reaction, and the cross-linking of multiple dimensions forms a complex and tight network structure, and the rigid cage structure of MA-POSS and the stilbene structure of REM also enhance the mechanical properties of the composites to a certain extent. The tendency of decreasing and then increasing can be explained by the fact that the characteristics of silica gel become more and more obvious as the proportion of POSS in the system increases. Compared with acrylate resins, silicone has poorer intermolecular forces and therefore lower mechanical properties. When POSS is increased to 50%, cracks encountering POSS and crystal domains during fracture will change their extension path, called "crack deflection"[27] which leads to the improvement of toughness and strength Fig.6. (C).
Fig. 4. (A) Tensile Strength and Elongation at break of MEP Composites and different REM/POSS Composites. (B) Toughness of MEP Composites and REM/POSS Composites.
3.5. Dielectric properties of MEP Composites and different REM/POSS Composites.
The arrival of the 5G era has prompted the rapid development of the electronics and information industry, which has increasing requirements for low dielectric constant materials[28] In the signal transmission process, signal delay and circuit loss are often accompanied. In the signal transmission process, often accompanied by signal delay and circuit loss, signal delay and dielectric material dielectric constant of the relationship between the dielectric constant as shown in equation (1).
(1)
Where Td is the signal delay , K is the coefficient and DK is the dielectric constant of the dielectric material. It can be seen that the lower the dielectric constant of the material, the lower the signal delay and the higher the signal fidelity. Therefore, in the context of the deep development of the fifth-generation communication technology, the use of low dielectric materials has become an effective way to reduce the signal hysteresis time[29] . The dielectric properties of composites have been studied in relation to the REM/POSS composition, as shown in Figure 5(A), the dielectric constants of all composites decrease slightly in the range of 2 GHz to 14.2 GHz due to the fact that the dipoles of the polymers are not able to keep up with the frequency change and are not fully polarized with the increase in frequency. The difference in dielectric constant between the commercial resin and the REM/POSS resin is very small. the REM/POSS-0% has a dielectric constant of 3.24 at 2 GHz. the dielectric constant increases when MA-POSS is added at 10%, which may be caused by the difficulty in mixing the POSS homogeneously in the viscous poorly flowing REM matrix (Fig. S4), and the results of the rheometer tests show that the shear rate of 600s−1 , the viscosity of REM/POSS-10% was 3164 cp (Figure S5), which was corroborated by the larger agglomerates in the SEM images of REM/POSS-10%, as shown in Figure 6 (A).The dielectric constant showed a decreasing tendency with the addition of 20% and 30% of MA-POSS, especially with the addition of 30% MA POSS is uniformly distributed in the REM matrix with only trace agglomerations Fig 6 (B), the dielectric constants of this composite are 2.97 and 2.90 at 2 GHz and 14.2 GHz, respectively, and this change may be due to the intrinsic porosity of MA-POSS and the molecular symmetric structure of MA-POSS leads to the equilibrium of dipole moments, and the polarization effect is weakened . However, when the MA-POSS content was further increased to 50%, the dielectric constant increased, which can be attributed to the fact that the excess MA-POSS somewhat compromised the integrity of the crosslinked network and exposed more polar groups[26] The potential aggregation of MA-POSS Fig 6 (C) and the interfacial polarization between the REM matrix and MA-POSSS[30, 31] also contribute to the deterioration of dielectric properties. The interfacial phenomenon can also explain the increase in dielectric loss of REM/POSS-50% composites with increasing POSS content.
Fig.5. (A) Dielectric constant and (B) Dielectric loss of MEP Composites and different REM/POSS Composites.
3.6 Application of information anti-counterfeiting.
In daily life, the security and storage of information play a very important role, and once threatened will seriously disturb the order of social development, and the development of secure anti-counterfeiting and authentication technology is a powerful means to overcome this challenge. Fluorescent anti-counterfeiting technology is well known and the most commonly used anti-counterfeiting technology because of its advantages such as wide material source, low cost, easy to use, good concealment and simple reaction mechanism[32, 33] The ideal fluorescent anti-counterfeiting material is the most commonly used anti-counterfeiting technology. The ideal fluorescent anti-counterfeiting material[34] The ideal fluorescent anti-counterfeiting material should have the following characteristics: tiny or colorless appearance under natural light, strong and multi-colored fluorescence under ultraviolet light, excellent stability, no biological toxicity, and compliance with safety and environmental protection standards. We selected the REM/POSS-20% composite resin with the best overall performance to be used for information security and information storage, as shown in Scheme 2, using a mask plate to encode the QR code onto the surface of the REM/POSS-20% composite material under UV light irradiation. The QR code is invisible under daylight, as in Figure 7 (D), but exhibits strong blue fluorescence under UV light irradiation, making it easy for smartphones to scan and encrypt the information. It was convenient for smartphones to scan and encrypt the information for retrieval (Figure S3). The letter "HZNU" was prepared by the same photo-printing process, as in Figure 7 (C). The results show that REM/POSS composites can be used as promising new luminescent materials in the field of information security and storage.
Scheme 2. Encipher message and scan.
3.7 Sample of the REM/POSS composites by DLP-based 3D printer
The widespread use of 3D printing technology in several fields has led to a significant increase in the demand for printing resins. Therefore, the development of renewable biomass resins that can replace conventional petroleum-based resins is of great significance for achieving sustainable development and reducing dependence on fossil fuels.
The performance of DLP3D printing resins after curing depends greatly on their photosensitivity, which will further affect the fine control of molded parts. In the layer-by-layer curing process, the layer thickness and the exposure time of each layer are the most important parameters[35] . REM/POSS composite resin was used for DLP printing to prepare three-dimensional patterns with well-defined structures. After debugging at a fixed wavelength of 405 nm, the printing parameters were determined, specifically, the curing time of each layer was 8 s, the thickness of each layer was 50 μm, and the "pyramid" shape pattern was successfully printed, which has a small volume shrinkage, good transparency, high precision, green environmental protection, and blue fluorescence under the irradiation of 365 nm UV (Figure 7). Figure.7.(a,b). In DLP printing, a resolution of less than 100 μm is considered a high-resolution benchmark for most commercial resin targets. In this work, we achieved a resolution of 50 μm, which exceeds that of some commercially available resins.REM/POSS-20% During 3D printing, there is no waste of resources due to cutting, and the material utilization rate of DLP printing can reach 60%, or even 90%[1] The material utilization rate of DLP printing can reach 60% or even 90%.
Fig.7. (A) DLP 3D printed pyramid of 2.5 cm × 2.5 cm; (B) DLP 3D printed pyramid of 2.0 cm × 2.0 cm; (C) Mask prepared letter "HZNU". (D) Mask prepared QR code.
Conclusions
Methacrylate monomer REM with trifunctionality was successfully prepared from resveratrol and used to prepare REM/MA-POSS composites. The results showed that with the increase of MA-POSS content, the mechanical properties showed a tendency of decreasing and then increasing, the tensile strength and elongation at break were gradually brought to equilibrium, and the thermal stability of REM/POSS composites was obviously enhanced. Compared with MEP/POSS-0%, REM/POSS-0% exhibits superior thermal stability as well as mechanical properties, which is mainly due to the inherent rigid stilbene structure of REM and more methacrylate groups involved in cross-linking. When 30 wt% MA-POSS was added, the dielectric properties of the resveratrol-based resin were optimized, with the dielectric constant decreasing to 2.90 at 14.2 GHz.QR codes were directly encoded onto the surface of the REM/POSS-20%-based composites and verified for information storage and encrypted retrieval under UV irradiation for applications. The successful printing of the "pyramid" structure using advanced DLP3D printing technology validates the applicability of MEP/POSS composite resin in DLP3D printing. Given the biocompatibility of resveratrol-based resins, we foresee their future applications, especially in the production of dental resins, biomedical and daily life products. In addition, this study offers a potential solution for reducing dependence on petroleum resources, which is important for promoting sustainable development and environmental protection.
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