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Article

The Fabrication of High-Hardness and Transparent PMMA-Based Composites by an Interface Engineering Strategy

by
Bo Cao
1,
Peng Wu
1,
Wenxiang Zhang
1,
Shumei Liu
1,2,* and
Jianqing Zhao
1,2,*
1
School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China
2
Key Lab Guangdong High Property & Functional Polymer Materials, and Key Laboratory of Polymer Processing Engineering, Ministry of Education, Guangzhou 510640, China
*
Authors to whom correspondence should be addressed.
Molecules 2023, 28(1), 304; https://doi.org/10.3390/molecules28010304
Submission received: 2 December 2022 / Revised: 23 December 2022 / Accepted: 27 December 2022 / Published: 30 December 2022
(This article belongs to the Special Issue Synthesis, Characterization and Application of Silicon Nanomaterials)
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Abstract

The high-hardness and transparent PMMA-based composites play a significant role in modern optical devices. However, a well-known paradox is that conventional PMMA-based composites with high loadings of nanoparticles usually possess high surface hardness at the cost of poor transparency and toughness due to the aggregation of nanoparticles. In this work, ideal optical materials (SiO2/PMMA composites) with high transparency and high surface hardness are successfully fabricated through the introduction of the flow modifier Si-DPF by conventional melt blending. Si-DPF with low surface energy and high transparency, which is located at the SiO2/PMMA interface, and nano-SiO2 particles are homogeneously dispersed in the PMMA matrix. As an example, the sample SiO2/PMMA/Si-DPF (30/65/5) shows outstanding transparency (>87.2% transmittance), high surface hardness (462.2 MPa), and notched impact strength (1.18 kJ/m2). Moreover, SiO2/PMMA/Si-DPF (30/65/5) also presents a low torque value of composite melt (21.7 N⋅m). This work paves a new possibility for the industrial preparation of polymer-based composites with excellent transparency, surface hardness, processability, and toughness.

1. Introduction

Poly (methyl methacrylate) (PMMA) has been widely used as an optical material for its high transparency, light weight, and low cost. Especially in recent years, PMMA has been used as display screens, lenses, and LED encapsulation materials [1,2,3]. PMMA has a high surface hardness and still needs to be improved by incorporating sufficient nanoparticles (i.e., SiO2 [4,5,6,7,8,9], TiO2 [9], ZrO2 [10], Al2O3 [11], and ZnO [12]) for wider applications. For instance, Tseng and coworkers [6] prepared the SiO2/PMMA composites (50/50 by weight) and the surface hardness reached 314 MPa, which was much higher than that of PMMA (196 MPa). Obviously, the high loading of nanoparticles is necessary to attain a high surface hardness of the composites.
However, the nanoparticles are easily packed together and inevitably form a large number of agglomerates in the PMMA matrix, which seriously deteriorates the properties of the composites, especially transparency [13,14]. Tadano et al. [7] introduced 9 wt% nano-SiO2 particles into PMMA to prepare the SiO2/PMMA hybrid films, and the transmittance of the samples was decreased from 91% to 72% due to the formation of SiO2 agglomerates. That is to say, the improvement in surface hardness of the PMMA-based composites by incorporating nanoparticles is achieved at the expense of reduced transparency. Moreover, the serious agglomeration of fillers generally results in poor processability and toughness of the composites, which is still urgently needed to be solved. Hence, incorporating nanoparticles into the PMMA matrix does not guarantee the fabrication of PMMA-based composites with high transparency and high surface hardness [15]. Only when nanoparticles do not aggregate and are uniformly dispersed in the PMMA matrix could high transparency and high surface hardness of the composites be simultaneously achieved [16]. In addition, achieving homogeneous dispersion of nanofillers in the polymer matrix is one of the hot research topics in modern material science [17].
PMMA-based composites are generally prepared by techniques including in-suit polymerization, modified polymerization, hot compression, and solution blending. It has been proven to be effective to introduce nanoparticles into PMMA by in-suit polymerization, forming a homogeneous dispersion of nanoparticles. A SiO2/PMMA composite (50/50) was synthesized via in-suit polymerization of methyl methacrylate and 2-(methacryloyloxy) ethyl isocyanate-modified SiO2 nanoparticles, and the composite simultaneously possessed a high surface hardness (363 MPa) and high transparency (>89% transmittance) [6]. Unfortunately, the application of the aforementioned method in the industry is difficult due to its complexity [18]. If the homogeneous dispersion of nanoparticles in the PMMA matrix is easy to be realized by melt blending, it is very convenient to fabricate ideal optical materials in an industry [19].
Our previous work demonstrated that the silicone/fluorine-functionalized flow modifier (Si-DPF) with low surface energy was located at the two-phase interface in the magnesium hydroxide/linear low-density polyethylene (MH/LLDPE) composites (80/20), and evidently improved the dispersion of MH particles [20]. In this work, the proposed flow modifier Si-DPF is applied to the production of SiO2/PMMA composites by a conventional melt processing technique, aiming to fabricate the SiO2/PMMA composites with high transparency, high surface hardness, excellent processability, and toughness. Herein, a small amount of Si-DPF (5 wt%) is introduced into SiO2/PMMA composites (the weight ratio of nano-SiO2 to PMMA is 10:90, 20:80, and 30:70, respectively). It is expected that the introduction of Si-DPF is conducive to the uniform dispersion of nano-SiO2 particles in the PMMA matrix, and the transparency of SiO2/PMMA composites is retained while the surface hardness is improved. Moreover, the dispersion and toughening mechanisms are explored. The present work provides a strategy for the development of transparent polymer-based nanocomposites for industrial production.

2. Results and Discussion

2.1. Phase Morphology

Improving the dispersion of nano-SiO2 particles in the PMMA matrix is a key to fabricating transparent SiO2/PMMA composites [21,22,23]. As we know, the more the nano-SiO2 particles are loaded, the more serious the SiO2 agglomeration. To display the effect of Si-DPF on the dispersion of highly filled nano-SiO2 particles, the morphology of nano-SiO2 particles in the samples SiO2/PMMA (30/70) and SiO2/PMMA/Si-DPF (30/65/5) is observed by SEM. Obviously, Si-DPF changes the dispersion of nano-SiO2 particles. There is a large amount of SiO2 agglomerates in the sample SiO2/PMMA (30/70) (Figure 1(a1,a2)), whereas nano-SiO2 particles are uniformly dispersed in the PMMA matrix for SiO2/PMMA/Si-DPF (30/65/5) (Figure 1(b1,b2)), indicating that Si-DPF plays an important role in the dispersion of highly filled nano-SiO2 particles.
Furthermore, to obtain the size and dispersion mechanism of nano-SiO2 particles, TEM tests are carried out on SiO2/PMMA composites, as shown in Figure 2.
Clearly, for the samples without Si-DPF, there exists a large amount of SiO2 agglomerates in the PMMA matrix (Figure 2(a1–a3)), where the average size of SiO2 agglomerates is about 430 nm, 450 nm, and 480 nm, respectively. By contrast, for the SiO2/PMMA composites with 5 wt% Si-DPF, the nano-SiO2 particles exhibit a homogeneous dispersion in the PMMA matrix and almost retain their original size of 20–40 nm without aggregation (Figure 2(b1–b3),c). Figure 2(d1) provides a TEM image of the sample SiO2/PMMA/Si-DPF (30/65/5), in which a relatively thinner interface between the nano-SiO2 particles and PMMA matrix is observed. The elemental mapping image (EMI) analysis is performed and the results are shown in Figure 2(d1–d3). Si signals are observed in the nano-SiO2 particles, and F signals are observed in the interface, indicating that Si-DPF tends to be located at the interface between the SiO2 particles and the PMMA matrix. Both SEM and TEM tests indicate that Si-DPF is able to effectively prevent nano-SiO2 particles from aggregating.

2.2. Surface Hardness

The surface hardness of SiO2/PMMA composites is evaluated by the nanoindentation tests [24]. Figure 3a shows that the PMMA matrix has a surface hardness of 236.4 MPa. The surface hardness of the samples is increased as the loading of nano-SiO2 particles, and the surface hardness is increased to 284.2 MPa for SiO2/PMMA (10/90), 355.8 MPa for SiO2/PMMA (20/80), and 491.2 MPa for SiO2/PMMA (30/70). As expected, the surface hardness is slightly decreased for the samples with Si-DPF. The results show that the long molecular chains of silicone in Si-DPF endow the samples with flexibility and reduce their hardness. Figure 3b shows the load-displacement curves by the nano-indenter. The harder sample requires more loading force for the tip to penetrate the same depth of 500 nm from the surface to the interior of the samples. The results in Figure 3a,b demonstrate that the surface hardness of SiO2/PMMA composites is obviously increased with the loading of nano-SiO2 particles and is easy to be adjusted.

2.3. Optical Properties

The transparency of SiO2/PMMA composites is crucial for their application as optical materials [25,26]. Figure 4a shows the transmittance spectra of the PMMA matrix, Si-DPF, and SiO2/PMMA samples, and the thickness of the samples is 1 mm. As seen, both PMMA and Si-DPF exhibit excellent transparency, which have a 91.1% and 86.8% transmittance at a wavelength of 760 nm, respectively. The transparency of SiO2/PMMA samples is decreased as the loading of nano-SiO2 particles, which originated from SiO2 agglomeration in the PMMA matrix. The aggregation of nanoparticles in a polymer matrix increases the refraction of light and leads to a decrease in transparency. The transmittance is decreased to 80.4% for SiO2/PMMA (10/90), 78.6% for SiO2/PMMA (20/80), and 77.3% for SiO2/PMMA (30/70) at a wavelength of 760 nm. The dispersion of nano-SiO2 particles is improved by the introduction of Si-DPF and the transparency of SiO2/PMMA samples is obviously increased. The transmittance is increased to 86.5% for SiO2/PMMA/Si-DPF (10/85/5), 86.6% for SiO2/PMMA/Si-DPF (20/75/5), and 87.2% for SiO2/PMMA/Si-DPF (30/65/5) at a wavelength of 760 nm, indicating that Si-DPF has an obvious advantage in improving the transparency of SiO2/PMMA composites. The transparency of the composites could also be observed with the naked eye. The images of SiO2/PMMA samples, as well as the PMMA matrix and Si-DPF, are displayed in Figure 4(b1–b8), which is unable to be distinguished by sight.
Moreover, the haze (H) is also used to evaluate the optical property of the composites, which is given by the ratio of the light diffusely scattered (Td) to the total light transmitted [27].
Tt) [H (%) = Td/Tt × 100%]
In Figure 4c, PMMA shows that the haze value is 20.01%. For SiO2/PMMA (10/90), when light passes through the interface, light-scattering would happen due to the different refractive index between the nano-SiO2 particles and the PMMA matrix, showing a higher haze value (37.27%). However, to our surprise, the haze value is decreased as the increase of nano-SiO2 particles loading, and the corresponding values are decreased to 27.04% for SiO2/PMMA (20/80) and 17.66% for SiO2/PMMA (30/70). This is attributed to the more serious agglomeration of SiO2 particles at the higher loading. The average size of SiO2 agglomerates increased and the total area of the interface between the PMMA matrix and SiO2 particles decreased. Consequently, the light-scattering is weakened and the haze values of the samples present a downward trend [28,29,30]. With the addition of Si-DPF, the nano-SiO2 particles exhibit a homogeneous dispersion in the PMMA matrix, and the total area of the interface between the PMMA matrix and SiO2 particles is obviously increased. The haze values are increased to 57.10% for SiO2/PMMA/Si-DPF (10/85/5), 38.35% for SiO2/PMMA/Si-DPF (20/75/5), and 34.26% for SiO2/PMMA/Si-DPF (30/65/5), respectively. The results further confirm that the Si-DPF is effective in improving the dispersion of nano-SiO2 particles in the PMMA matrix.
Table 1 summarizes the reported transparency and surface hardness enhancement for PMMA-based composites with various nanoparticles. As seen, few studies on PMMA-based composites have focused on transparency and surface hardness simultaneously. It is noted that the PMMA-based composites with higher nano-SiO2 particle contents in this work show higher transparency and higher surface hardness enhancement. This work provides a relatively more efficient and facile method to improve the transparency and surface hardness of PMMA-based composites.

2.4. Processability

The processability of the composites is critical for engineering applications, which is evaluated by the torque rheology test. Figure 5 shows the torque vs. time curves for SiO2/PMMA composites. As seen, the equilibrium torque of composite melt is increased as the loading of nano-SiO2 particles and Si-DPF can decrease the melt torque. For samples SiO2/PMMA (10/90), SiO2/PMMA (20/80), and SiO2/PMMA (30/70), the stable torque values are 19.0 N⋅m, 23.1 N⋅m, and 26.3 N⋅m, respectively. With the addition of Si-DPF, the torque values of the samples are decreased, and the corresponding ones are decreased to 15.0 N⋅m for SiO2/PMMA/Si-DPF (10/85/5), 17.1 N⋅m for SiO2/PMMA/Si-DPF (20/75/5), and 21.7 N⋅m for SiO2/PMMA/Si-DPF (30/65/5), respectively, indicating an improvement in processability. The complex viscosity η* is also used to evaluate the processability of composites, and Figure 5b shows the curves of complex viscosity (η*) vs. frequency (ω) for the samples. As seen, the η* of samples are obviously increased with the loading of nano-SiO2 particles, and the viscosity values of SiO2/PMMA samples are decreased with the addition of Si-DPF. This result is ascribed to the improvement in the dispersion of nano-SiO2 particles; that is, Si-DPF tends to be located at the interface, which prevents nano-SiO2 particles from aggregation and results in a decrease in the melt viscosity [20].

2.5. Toughness

Usually, the toughness of high-filled PMMA is decreased. To assess the toughness of SiO2/PMMA composites with and without Si-DPF, the notched impact test of the PMMA matrix and the SiO2/PMMA composites is conducted, and the results are shown in Figure 6. As seen, the PMMA matrix presents an impact strength of 1.12 kJ/m2. Undoubtedly, the notched impact strength of SiO2/PMMA samples is decreased, as the loading of nano-SiO2 particles and the strengths are decreased to 1.04 kJ/m2 for SiO2/PMMA (10/90), 0.99 kJ/m2 for SiO2/PMMA (20/80), and 0.96 kJ/m2 for SiO2/PMMA (30/70). The decrease in strength originated from the SiO2 agglomerates in the PMMA matrix. By contrast, the notched impact strength of SiO2/PMMA/Si-DPF (10/85/5), SiO2/PMMA/Si-DPF (20/75/5), and SiO2/PMMA/Si-DPF (30/65/5) are 1.17 kJ/m2, 1.21 kJ/m2, and 1.18 kJ/m2, respectively. These samples exhibit a higher notched impact strength and better toughness compared to the PMMA matrix, showing that Si-DPF has a positive effect on improving the toughness of SiO2/PMMA composites. Si-DPF with low surface energy tends to be located at the phase interface, which not only plays the role of dispersing nano-SiO2 particles but also transfers the energy. When the samples are impacted by the external force, the energy is transferred to the small aggregates, which act as a stress concentration point to dissipate energy; thus, the toughness is improved.
Nano-SiO2 particles aggregate easily due to the high surface energy. Therefore, weakening the interaction between nano-SiO2 particles is critical for improving the dispersion of nano-SiO2 particles. Si-DPF with low surface energy prefers to locate at the SiO2/PMMA interface, forming a protective layer on the SiO2 particles, and reducing the SiO2 agglomeration. For the highly filled SiO2/PMMA composites, the uniformly dispersed particles could help to improve the transparency of the composites while maintaining high surface hardness. As a protective layer, Si-DPF contributes to the relative sliding of nano-SiO2 particles under an applied stress during the melt blending stage, reducing the melt viscosity of the samples and thus improving processability.

3. Experimental

3.1. Main Materials

The commercially available poly (methyl methacrylate) (PMMA, CM-211) was purchased from Chimei Taiwan Co., Ltd., with a melt flow rate of 7 g/10 min (Tainan, Taiwan, China). Silica (nano-SiO2, A-200, 2.2 g/cm3) was supplied by Shandong Dongyue Silicone Material Co., Ltd., with a specific area of 180–220 m2/g and a mean diameter of 10–40 nm (Zibo, Shandong, China). The synthesis of the silicone/fluorine-functionalized flow modifier (Si-DPF) referred to our previous work (CST. 2021, 214, and 108994) [20].

3.2. Fabrication of SiO2/PMMA Composites

PMMA was dried in a vacuum oven at 80 °C for 12 h. SiO2/PMMA composites were prepared by melt blending in a twin-screw extruder at a screw speed of 150 rpm. The extruder was configured with ten heating zones, and the extrusion was carried out at zone temperatures of 165 °C, 170 °C, 170 °C, 175 °C, 175 °C, 175 °C, 180 °C, 180 °C, 185 °C, and 185 °C, respectively. After being granulated and dried, the pellets were injection-molded on an injection-molding machine to obtain different specimens. The temperatures of the injection-molding machine were set in a range from 175 °C to 195 °C. The formulation of SiO2/PMMA samples is listed in Table 2.

3.3. Analysis and Characterization

Scanning electron microscopy (SEM) images were obtained with a Nova NanoSEM430 scanning electron microscope (FEI, Hillsboro, OR, USA) operating at 20 kV. Samples were fractured in liquid nitrogen and the fracture surfaces were coated with gold before observation. Transmission electron microscopy (TEM) images were obtained with a JEM 2100F transmission electron micrograph (JEOL, Tokyo, Japan) operating at 100 kV. Samples were prepared by cutting the blends into approximately 50 nm slices with an RMC PowerTome. Transmittance spectra of the samples were recorded on a Hitachi U-3900H spectrometer (Hitachi, Tokyo, Japan) in a range from 500 to 800 nm. The haze of the samples was measured by an SGW-820 haze meter (Shanghai INESA Physico-Optical Instrument, Shanghai, China) under standard illuminant D65 and in compliance with ASTM D1003. The surface hardness of the samples was measured on a TTX-NHT3 nanoindentation instrument (Anton Paar, Graz, Austria) with a Berkovich diamond tip at room temperature. The test speed was constant at 5 mN/min and the maximum depth was 500 nm. The processability of the samples was measured on a Haake XSS-300 torque rheometer (Haake, Vreden, Germany) at a rotation rate of 50 rpm at 180 °C for 10 min. The complex viscosity of the samples (the sample disks with 25 mm diameter and 1 mm thickness) was carried out on a stress-controlled rheometer (AR-G2, TA Instruments, NC, USA) in a dynamic frequency sweep from 0.1 to 628 rad s−1 at a strain of 1% within the linear viscoelastic range at 180 °C. According to the ISO 179-1:2000 standards, the impact strength of the samples was tested on a Zwick5113 impact pendulum machine (ZwickRoell, Ulm, Germany). At least five specimens were tested for each measurement and the average results were reported.

4. Conclusions

We successfully achieved the properties of high transparency, high surface hardness, excellent processability, and toughness in high-performance SiO2/PMMA composites by using the conventional melt mixing technique, solving the well-known problem that high loading of nano-SiO2 particles is easy to aggregate and the problem of SiO2 agglomerates deteriorating the transparency and toughness of the composites. The 30 wt% nano-SiO2 particles, uniformly dispersed in the PMMA matrix with the help of Si-DPF located at the phase interface, facilitated the building of a perfect composite with high transparency and high surface hardness, compared with SiO2/PMMA composites with a serious agglomeration of SiO2. In addition, the fabricated SiO2/PMMA composites also presented excellent toughness and processability. This work provides a quick and effective strategy for improving the production efficiency of commercially available polymer-based composites with high transparency and high surface hardness, which pave a way for their application as ideal optical materials, such as display screens, lenses, and LED lighting.

Author Contributions

Conceptualization, B.C. and J.Z.; methodology, B.C. and P.W.; software, W.Z.; validation, P.W. and W.Z.; investigation, B.C. and P.W.; data curation, S.L.; writing—original draft preparation, B.C.; writing—review and editing, J.Z.; visualization, P.W.; supervision, S.L. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by Guangdong Basic and Applied Basic Research Foundation (No. 2021A1515110134) and the Opening Project of Key Laboratory of Polymer Processing Engineering (South China University of Technology), Ministry of Education (No. KFKT2102).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Conflicts of Interest

The authors declare no conflict of interest.

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  30. Wu, G.; Guo, S.; Yin, Y.; Sun, G.; Zhong, Y.; You, B. Hollow Microspheres of SiO2/PMMA Nanocomposites: Preparation and Their Application in Light Diffusing Films. J. Inorg. Organomet. Polym. 2018, 28, 2701–2713. [Google Scholar] [CrossRef]
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Figure 1. SEM images of SiO2/PMMA (30/70) (a1,a2) and SiO2/PMMA/Si-DPF (30/65/5) (b1,b2).
Figure 1. SEM images of SiO2/PMMA (30/70) (a1,a2) and SiO2/PMMA/Si-DPF (30/65/5) (b1,b2).
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Figure 2. TEM images of SiO2/PMMA composites. (a1) SiO2/PMMA (10/90), (a2) SiO2/PMMA (20/80), (a3) SiO2/PMMA (30/70), (b1) SiO2/PMMA/Si-DPF (10/85/5), (b2) SiO2/PMMA/Si-DPF (20/75/5), and (b3,d1) SiO2/PMMA/Si-DPF (30/65/5). (c) SiO2 particle size of SiO2/PMMA composites. (d2,d3) Elemental mapping images of Si and F.
Figure 2. TEM images of SiO2/PMMA composites. (a1) SiO2/PMMA (10/90), (a2) SiO2/PMMA (20/80), (a3) SiO2/PMMA (30/70), (b1) SiO2/PMMA/Si-DPF (10/85/5), (b2) SiO2/PMMA/Si-DPF (20/75/5), and (b3,d1) SiO2/PMMA/Si-DPF (30/65/5). (c) SiO2 particle size of SiO2/PMMA composites. (d2,d3) Elemental mapping images of Si and F.
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Figure 3. Surface hardness of the PMMA matrix and SiO2/PMMA composites. (a) Hardness. (b) Load-displacement curves.
Figure 3. Surface hardness of the PMMA matrix and SiO2/PMMA composites. (a) Hardness. (b) Load-displacement curves.
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Figure 4. (a) Transmittance spectra of PMMA matrix, Si-DPF, and SiO2/PMMA samples with a thickness of 1 mm. (b) Images of PMMA matrix (b1), Si-DPF (b2), and SiO2/PMMA samples (b3–b8). (c) The haze value of the PMMA matrix and SiO2/PMMA samples.
Figure 4. (a) Transmittance spectra of PMMA matrix, Si-DPF, and SiO2/PMMA samples with a thickness of 1 mm. (b) Images of PMMA matrix (b1), Si-DPF (b2), and SiO2/PMMA samples (b3–b8). (c) The haze value of the PMMA matrix and SiO2/PMMA samples.
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Figure 5. (a) Torque rheological analysis of SiO2/PMMA composites. (b) Complex viscosity versus frequency of samples. Temperature: 180 °C.
Figure 5. (a) Torque rheological analysis of SiO2/PMMA composites. (b) Complex viscosity versus frequency of samples. Temperature: 180 °C.
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Figure 6. Impact strengths of the PMMA matrix and SiO2/PMMA composites.
Figure 6. Impact strengths of the PMMA matrix and SiO2/PMMA composites.
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Table 1. A comparison of the transmittance and surface hardness enhancement in PMMA-based composites with various nanoparticles.
Table 1. A comparison of the transmittance and surface hardness enhancement in PMMA-based composites with various nanoparticles.
SamplesStrategyFiller Loading [wt%]Transmittance [%, 760 nm]Surface Hardness Enhancement [%]Year [Ref]
SiO2/PMMAIn situ polymerization37.59080.02005 [4]
SiO2/PMMA478-2005 [5]
ZnO/PMMA565-2018 [12]
SiO2/PMMA≈388-2020 [9]
TiO2/PMMA≈387-2020 [9]
SiO2/PMMAModified polymerization5089.585.22006 [6]
SiO2/PMMA13.590-2019 [8]
ZrO2/PMMAHot compression1.5-12.32011 [10]
Al2O3/PMMA3-29.82020 [11]
SiO2/PMMASolution blending9.172-2014 [7]
SiO2/PMMAMelt blending3087.295.5This work
Table 2. Formulation of various SiO2/PMMA samples.
Table 2. Formulation of various SiO2/PMMA samples.
SamplesSiO2 (g)PMMA (g)Si-DPF (g)
SiO2/PMMA (10/90)1090-
SiO2/PMMA/Si-DPF (10/85/5)10855
SiO2/PMMA (20/80)2080-
SiO2/PMMA/Si-DPF (20/75/5)20755
SiO2/PMMA (30/70)3070-
SiO2/PMMA/Si-DPF (30/65/5)30655
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Cao, B.; Wu, P.; Zhang, W.; Liu, S.; Zhao, J. The Fabrication of High-Hardness and Transparent PMMA-Based Composites by an Interface Engineering Strategy. Molecules 2023, 28, 304. https://doi.org/10.3390/molecules28010304

AMA Style

Cao B, Wu P, Zhang W, Liu S, Zhao J. The Fabrication of High-Hardness and Transparent PMMA-Based Composites by an Interface Engineering Strategy. Molecules. 2023; 28(1):304. https://doi.org/10.3390/molecules28010304

Chicago/Turabian Style

Cao, Bo, Peng Wu, Wenxiang Zhang, Shumei Liu, and Jianqing Zhao. 2023. "The Fabrication of High-Hardness and Transparent PMMA-Based Composites by an Interface Engineering Strategy" Molecules 28, no. 1: 304. https://doi.org/10.3390/molecules28010304

APA Style

Cao, B., Wu, P., Zhang, W., Liu, S., & Zhao, J. (2023). The Fabrication of High-Hardness and Transparent PMMA-Based Composites by an Interface Engineering Strategy. Molecules, 28(1), 304. https://doi.org/10.3390/molecules28010304

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