Morphology and properties of UV-curing epoxy acrylate coatings modified with methacryl-POSS

doi:10.1016/j.porgcoat.2014.07.003

Progress in Organic Coatings

Volume 78, January 2015, Pages 404-410

https://doi.org/10.1016/j.porgcoat.2014.07.003 Get rights and content

Highlights

•
The M-POSS nanocages have chemically incorporated into the hybrid materials.
•
The addition of POSS enhanced both of the UV-curing rates and final double bond conversion.
•
The nanocomposite's T_g increased with the increasing M-POSS loadings.
•
The thermal stability and impact resistance of nanocomposites were enhanced by the addition of M-POSS.

Abstract

In this work, the morphology and properties of UV-curing epoxy acrylate (EA) coatings modified with methacryl polyhedral oligomeric silsesquioxanes (M-POSS) were studied. The M-POSS nanocages were introduced into EA UV-curing system via copolymerization at loadings between 0% and 10 wt%. The XRD and FTIR analysis indicated that M-POSS chemically incorporated into the hybrid materials and formed a cross-linked network between M-POSS and EA. The morphological analysis showed that the discrete spherical POSS-rich particles were dispersed in the EA matrix uniformly, and both of the number and mean diameter of POSS-rich particles increased with the increasing M-POSS loadings. The influence of M-POSS on the kinetics of the photopolymerization was determined by real time FTIR spectroscopy and the result showed that the addition of POSS enhanced both of the UV-curing rates and final double bond conversion. The DMA analysis showed that increasing the amount of M-POSS nanocages caused an increase on the nanocomposite's T_g. TGA curves showed that at the later period of degradation process, the thermal stability of nanocomposites was enhanced by M-POSS. With respect to the mechanical properties, the most remarkable trend was an improvement on the impact resistance of nanocomposites with the increasing POSS contents. Because both of the craze and plasticity deformation caused by POSS nanocages would absorb impact energy, hinder the growth of craze.

Introduction

The UV-curing technology has been widely used in industrial coatings owing to many advantages, including no emission of volatile organic compounds, low energy consumption, low process costs, high chemical stability, ultrafast curing rate and ambient temperature operation [1], [2]. The epoxy acrylate (EA) is one of the most important and extensively used acrylate monomer in UV-curing systems due to its excellent properties, such as superior chemical and solvent resistance, good adhesion properties and high mechanical strength [3], [4]. In the last few years, the improvement of thermal stability and mechanical properties of EA networks by the incorporation of nanofillers has drawn many attentions [5], [6], [7], [8].

In the last two decades, polyhedral oligomeric silsesquioxanes (POSS) have been used as a novel class of nanofillers with unique properties [9]. Polyhedral oligomeric silsesquioxanes (POSS) is a class of organic–inorganic hybrid nanomaterial constituted by an inorganic silica R_n(SiO_1.5)_n core cage structure, where n (n = 8, 10 or 12) is the number of silicon atoms of the cage and the R is a hydrogen atom or an organic functional group such as alkyl, alkylene, acrylate, hydroxyl, or epoxide unit. These functional groups attached on POSS make it easier to incorporate with thermoplastics or thermosets, and finally lead to the improvement of properties, such as thermal stability, thermomechanical and electrical properties, flame retardant as well as mechanical strength [10], [11], [12], [13]. POSS cages can be introduced into polymer systems via copolymerization or physical blending [14]. Traditionally, copolymerization is the most common approach used to obtain polymer/POSS nanocomposites. The incorporation of POSS monomer into polymers by this way can lead to the improvement of the miscibility and other properties [15], [16]. Nanocomposites obtained by physical blending, including melt blending and solution blending, own the advantages of being inexpensive and simple to scale up at industrial level, however, poor miscibility may exist generally [17], [18], [19], [20], [21].

In previous studies, few investigations have reported the synthesis of polymer/POSS nanocomposites employing UV-curing technology. Wang et al. [3] studied the preparation and thermal stability of UV-cured epoxy-based coatings modified with octamercaptopropyl POSS. The octamercaptopropyl-POSS was incorporated into epoxy acrylate networks by thiol-ene photopolymerization. La et al. [22] investigated novel anti-fouling coatings prepared with a UV-curable-molecular reinforcing material, methacryl-POSS, and a hydrophilic comonomer, polyethylene glycol methacrylate (PEGM). Water uptake of the UV-cured POSS–PEGM films was varied from 8% to 90% depending on the relative ratio between POSS and PEGM. Gao et al. [23] prepared the waterborne UV-curable EA coatings modified with methylacryloylpropyl-POSS and investigated the cure kinetics of the coating by differential scanning calorimetry (DSC). Few works have studied the influence of POSS on the kinetics of the photopolymerization and the mechanical properties of nanocomposites.

In our previous study, we have synthesized UV-curing EA/vinyl-POSS nanocomposites via physical blending [24]. The microstructure and thermal properties of the EA/vinyl-POSS composites was studied. In this work, in order to improve the dispersion of POSS molecules in EA matrix, methacryl-POSS (M-POSS) were introduced into UV-curing systems. Methacryl-POSS is a hybrid molecule with an inorganic silsequioxane as the cage-like core, and organic methacrylate groups attached at the corners of the cage. It is a kind of colourless and transparent liquid with low viscosity. It is soluble in most of polar organic solvents, acrylate and methacrylate monomers, and aromatic and aliphatic resins. The molecular structures of methacryl-POSS and epoxy acrylate are shown in Scheme 1. Methacryl-POSS was utilized because the methacrylate groups can copolymerize with epoxy acrylate (Scheme 2). The microstructure and morphology of EA/methacryl-POSS nanocomposites were investigated by FTIR, XRD, SEM and TEM. The influence of M-POSS on the kinetics of the photopolymerization was determined by real time FTIR spectroscopy. The glass transition temperature and thermal stability were tested by DMA and TGA, respectively. The mechanical properties of the EA/POSS nanocomposite films were investigated employing pencil hardness, impact resistance and flexibility tests.

Section snippets

Materials

Epoxy acrylate (EA, Product No.: CN120), as photosensitive oligomer, was provided by Sartomer USA, LLC, used as received. Methacryl-POSS (M-POSS, Product No.: MA0735, (C₇H₁₁O₂)_n(SiO_1.5)_n; n = 8, 10, 12, F_w: 1433.97) was obtained from Hybrid Plastics, Inc. Benzophenone (BP, M_w: 182.22 g/mol, CAS No.: 119-61-9) and triethanolamine (TEA, M_w: 149.19 g/mol, CAS No.: 102-71-6), as photoinitiators, were purchased from Sinopharm Chemical Reagent Shengyang Co., Ltd., China. Tripropylene glycol diacrylate

FTIR analysis

Fourier transform infrared spectroscopy (FTIR) is an effective method of investigating specific interactions during polymerization process. Fig. 1 shows the FTIR spectra of the uncured EA, EA film, M-POSS and 10% mass M-POSS reinforced EA film. The uncured EA and M-POSS are characterized by the stretching vibration band of carbon–carbon double bonds at 1635 cm⁻¹ and the absorption peak of carbon hydrogen bonds linked to carbon–carbon double bonds at 810 cm⁻¹. As can be seen from the FTIR spectra

Conclusions

The FTIR spectra of nanocomposites containing 10 wt% of POSS showed that the carbon–carbon double bonds at 1635 cm⁻¹ and 810 cm⁻¹ of nanocomposites were almost disappeared, and the intensity of band at 1120 cm⁻¹

Acknowledgments

The financial support of the National Natural Science Foundation of China (No. 51074053) is gratefully acknowledged.

References (33)

M. Sangermano et al.
Prog. Org. Coat.
(2005)
S. Ceccia et al.
Prog. Org. Coat.
(2008)
X. Wang et al.
Thermochim. Acta
(2013)
A. Fieberg et al.
Prog. Org. Coat.
(2002)
M.N. dos Santos et al.
Mater. Sci. Eng. A: Struct.
(2011)
H.M. Lin et al.
Mater. Chem. Phys.
(2011)
X.Y. Xiao et al.
Colloid Surf. A
(2010)
S.W. Kuo et al.
Prog. Polym. Sci.
(2011)
Y.J. Lee et al.
Polymer
(2006)
J. Boček et al.
Eur. Polym. J.
(2011)

M. Sánchez-Soto et al.

Eur. Polym. J.

(2009)

R. Bouza et al.

Compos. B: Eng.

(2014)

C. Ramírez et al.

Eur. Polym. J.

(2008)

Y. Ni et al.

Polymer

(2004)

M. Hoyos et al.

Polym. Degrad. Stabil.

(2011)

H. Zhang et al.

Eur. Polym. J.

(2009)

Cited by (58)

Micro-fabrication of glassy carbon with low shrinkage and high char yield using high-performance photocurable phthalonitrile (PN) resins
2024, Additive Manufacturing
Glassy carbons (GCs) are a significant class of materials that have attracted considerable attention in many scientific and technical fields due to their great thermal and chemical stability, excellent biocompatibility, and remarkable thermal and electrical conductivity. However, the thermal resistance and brittle nature of GCs pose limitations on their processing using conventional techniques such as melting extrusion or sintering. 3D printing as a rapidly developing technology advances product fabrication in prototyping and tooling provides a revolutionizing alternative of material processing with the advantage of accurately producing complex structures/shapes. This study demonstrates the micro-fabrication of GC objects based on novel photocurable high-performance phthalonitrile (PN) resins with a vat photopolymerization printing technology named as projection micro stereolithography (PμSL). In initial, soluble acrylate PN monomers are successfully developed and subsequently formulated into photopolymerizable resins. The resultant resins show excellent thermal and mechanical properties with T_g around 300 °C and flexural strength of 150 MPa after post thermal treatment. Being fabricated into 3D structures via PμSL printing, the obtained PN based objects are converted to GC products through pyrolysis in inert atmosphere with high char yield and low shrinkage. As a result, diverse microscale 3D GC objects are achievable and exhibit excellent structural integrity and fidelity. Our approach develops the micro-fabrication of dense and complex structured GC for the first time, providing a versatile functional platform for advancing next generation applications in medical tools, electrochemistry and precision micro-moulding as well as in energy and aerospace technologies.
Non-halogenated UV-curable flame retardants for wood coating applications: Review
2023, Progress in Organic Coatings
The prospective applications of wood in the furniture industries and building sector are constrained owing to its inherently flammable nature. The application of coatings with flame retardants (FRs) onto the wood substrate is a well-recommended approach to mitigate the risk of fire. Non-halogenated FRs, on the other hand, have gained popularity over halogenated FRs, as halogenated FRs are under regulatory scrutiny due to their carcinogenicity and bio-accumulation issues despite offering excellent FR performance. Furthermore, given the green chemistry principles, it is also recommended to use solvent-free or environmentally benign solvents to make such coatings. The ultraviolet (UV)-assisted curing process is advantageous as it can in practice avoid the use of solvents. A few relevant pieces of literature were found in the bibliographic search databases from January 2015 to December 2022 on UV-curable, non-halogenated FRs for wood coating applications. The current review focuses on the design strategies of reactive and non-halogenated FRs with UV-curable functionalities adapted in recent years, and their applications in various UV-curing polymeric systems such as epoxy acrylate, polyurethane acrylate, thiol-ene systems, and oligomeric systems obtained from bio-based oils'. The significant findings of several research groups, the major insights gained and perspectives are covered.
Polyhedral oligomeric silsesquioxane grafted covalent organic frameworks for simultaneously improved tribological and corrosion resistance of epoxy coatings
2022, Progress in Organic Coatings
In this work, polyhedral oligomeric silsesquioxane (POSS) was covalently grafted on 2D covalent organic framework of TpPa-1 through Schiff base reaction (POSS-TpPa-1) to synergistically improve the corrosion and tribological resistance of epoxy coating. The results show that compared with the hydrophilic TpPa-1, POSS-TpPa-1 exhibits excellent hydrophobicity, and the water contact angle can reach 134°. Furthermore, POSS-TpPa-1 with different weight ratios was added into epoxy coating, and the anti-corrosion and wear resistance of the composite coatings were studied through electrochemical impedance spectroscopy (EIS) and friction and wear tests, respectively. The EIS results show that when the additive amount of POSS-TpPa-1 is 2 wt%, the impedance modulus in the low frequency region can maintain 1.04 × 10⁹ Ω·cm² even after being immersed in 3.5 wt% NaCl solution for 60 days, indicating its good anti-corrosion performance. The friction and wear experiments show that the epoxy composite coating with 2 wt% POSS-TpPa-1 exhibits the lowest friction coefficient of 0.23, suggesting that POSS-TpPa-1 can effectively improve the friction resistance of the coating under the premise of good dispersion. This work develops a new composite filler to simultaneously improve the anticorrosion and wear resistance of epoxy coating, which might be able to trigger further studies to develop more advanced composite coating by incorporating 2D-COF.
Si-containing 3D cage-functionalized graphene oxide grafted with Ferrocene for high-performance supercapacitor application: An experimental and theoretical study
2022, Journal of Energy Storage
In this work, graphene oxide sheets were functionalized with Octa(aminopropyl)silsesquioxane. Then, Octa(aminopropyl)silsesquioxane-functionalized graphene oxide (GO-Amine-SSQ) was grafted with Ferrocene through Friedel-Craft reaction. Structural properties of the prepared composite (GO-Amine-SSQ-Fc) were analyzed by XPS, FT-IR, XRD, Raman, SEM, TEM, and BET tests. Results confirmed the successful synthesis and high porosity. Next, the electrochemical properties of GO-Amine-SSQ-Fc were characterized by CV, GCD, and EIS techniques in the 3E system. The GO-Amine-SSQ-Fc electrode showed a specific capacitance of 574 F g⁻¹ at 1 A g⁻¹, retention capacitance of 90.1% after 10,000 charge-discharge cycles, low resistance, and efficient diffusion of ions. After confirming the excellent electrochemical performance of this electrode, a symmetric supercapacitor system (GO-Amine-SSQ-Fc//GO-Amine-SSQ-Fc) was tested by CV and GCD techniques, to determine practical application of system. GO-Amine-SSQ-Fc//GO- Amine-SSQ-Fc system recorded a specific capacitance of 304 F g⁻¹ at 0.5 A g⁻¹, retention capacitance of 92.5% over 10,000 charge-discharge cycles, and specific energy of 10.14 Wh kg⁻¹ at a specific power of 500 W kg⁻¹. Also, the results of computational methodology show that the interaction of SSQ, Fc and GO layer in GO-Amine-SSQ-Fc composite, makes it effective as an electrode material for supercapacitors. This excellent performance, as a result of the unique structure of Amine-SSQ groups and the superior electrochemical behavior of Ferrocene groups, suggests that GO-Amine-SSQ-Fc composite has great potential for energy storage devices.
High-performance UV-curable epoxy acrylate nanocomposite coatings reinforced with aramid nanofibers
2022, Progress in Organic Coatings
UV-curing epoxy acrylate (EA) nanocomposite films with different amounts of aramid nanofibers (ANFs) synthesized by a bottom-up method were prepared. The effects of the ANFs on the coating microstructures, curing kinetics, optical light transmittance, mechanical properties, and thermal stability were investigated. Although the ANFs strongly absorb UV light, ANF incorporation did not decrease the final CC bond conversion of the nanocomposites. The UV transmittance of the nanocomposite films decreased dramatically with increasing ANF content, but all films maintained a high visible transmittance. Relative to neat EA, the tensile strength of the 0.05 wt% ANF-reinforced nanocomposites increased by 36%, and the elongation at break of the 0.1 wt% ANF-reinforced nanocomposites increased by 194%. This was mainly attributed to the favorable ANF mechanical properties and their strong interactions (hydrogen bonds and π–π stacking) with EA. This work demonstrates that a small amount of ANFs can enhance the UV-shielding and mechanical properties of UV-curable EA coatings without affecting the transparency or final conversion.
High-transparency polysilsesquioxane/glycidyl-azide-polymer resin and its fiberglass-reinforced composites with excellent fire resistance, mechanical properties, and water resistance
2021, Composites Part B: Engineering
Citation Excerpt :
The use of commercial allyl-functional POSS, on the one hand, can increase the mutual solubility between polymers and, on the other hand, can form stable organic-inorganic building blocks in the network structure; an example of this is the application of allyl-functional POSS in coatings, resins, and composites [33,34]. This is mainly because the allyl structure is compatible with other typical organic groups and can also undergo polymerization with unsaturated groups [35]. These POSS possess the reaction characteristics of unsaturated polyester resins and can be used as a substitute for traditional thermosetting resins [34–36].
New high-performance polymer composites are desirable for various industrial applications. Two unsaturated polysilsesquioxanes (AcPhPOSSⅠ and AcPhPOSSⅡ) were designed and synthesized successfully, and their thermosetting resins (AcPhPOSS@GAP) and fiberglass-doped composites (AcPhPOSS@GAP@GF) were prepared by thermal curing of AcPhPOSS and glycidyl azide polymer (GAP). AcPhPOSS@GAP exhibited excellent transparency, especially AcPhPOSSⅡ@GAP with a transparency and haze of 84.0% and 3.0%, respectively. The heat and smoke release rates of AcPhPOSS@GAP@GF were about 69% and 50% lower, respectively, than those of AcPhPOSS@GAP. Further, the flexural strength and flexural modulus of AcPhPOSS@GAP@GF remained above 80 MPa and 11,000 MPa, respectively, after water treatment. This was due to the strong adhesion between the fiberglass and the matrix, which enabled them to effectively withstand the impact of adverse external conditions. AcPhPOSS@GAP@GF presented a low dielectric loss and high thermal conductivity, which prevented damage caused by heat accumulation. Thus, the prepared materials have excellent application prospects.

View all citing articles on Scopus

View full text

Morphology and properties of UV-curing epoxy acrylate coatings modified with methacryl-POSS

Highlights

Abstract

Introduction

Section snippets

Materials

FTIR analysis

Conclusions

Acknowledgments

Prog. Org. Coat.

Prog. Org. Coat.

Thermochim. Acta

Prog. Org. Coat.

Mater. Sci. Eng. A: Struct.

Mater. Chem. Phys.

Colloid Surf. A

Prog. Polym. Sci.

Polymer

Eur. Polym. J.

Eur. Polym. J.

Compos. B: Eng.

Eur. Polym. J.

Polymer

Polym. Degrad. Stabil.

Eur. Polym. J.