J Mater Sci POLYMERS Polymers
Marvelous abilities for polyhedral oligomeric silsesquioxane to improve tribological properties of polyamide-imide/polytetrafluoroethylene coatings Chuanyong Yu1,2, Hongqi Wan1, Lei Chen1,* Jianmin Chen1
, Hongxuan Li1,*, Haixia Cui1,*, Pengfei Ju3, Huidi Zhou1, and
1
State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, People’s Republic of China 2 University of Chinese Academy of Sciences, Beijing 100080, People’s Republic of China 3 Shanghai Aerospace Equipment Manufacture, Shanghai 200245, People’s Republic of China
Received: 6 March 2018
ABSTRACT
Accepted: 17 May 2018
POSS-doped organic–inorganic nanocomposites (POSS referring to polyhedral oligomeric silsesquioxane) as a new generation of high-performance materials are of special significance, since they simultaneously possess the high rigidity and stability of inorganic species as well as the desired flexibility, ductility and processability of polymer species. Thus, octa(3-amino propyl) POSS (aminofunctionalized POSS, denoted as NH2-POSS) was incorporated into polyamideimide (denoted as PAI) to obtain a series of NH2-POSS/PAI hybrid composites. The molecular structures of NH2-POSS and NH2-POSS/PAI hybrid composites were analyzed by Fourier transform infrared spectrometry and X-ray diffraction. The impact of NH2-POSS on the thermal stability and mechanical properties of PAI as well as the tribological properties of PAI/PTFE-based (PTFE referring to polytetrafluoroethylene) bonded solid lubricant coatings was investigated. Findings indicate that the introduction of a proper amount of NH2POSS leads to an increase in the glass transition temperature (Tg) as well as hydrophobicity and microhardness of PAI. Besides, NH2-POSS contributes to reducing the friction coefficient and wear rate of PAI/PTFE-bonded solid lubricant coatings. Particularly, the introduction of 7% (mass fraction) of NH2POSS leads to a decrease in the wear rate of PAI/PTFE-bonded solid lubricant coating by about 50%. This could be attributed to the increase in the loadbearing capacity and decrease in the surface energy of the polymer matrix coatings upon the addition of NH2-POSS.
Ó
Springer Science+Business
Media, LLC, part of Springer Nature 2018
Address correspondence to E-mail:
[email protected];
[email protected];
[email protected] https://doi.org/10.1007/s10853-018-2475-1
J Mater Sci
Introduction Polymer matrix composites are widely applied for reducing the friction and wear of mechanical facilities, because they often possess outstanding flexural performance coupled with high stiffness and strength, relatively easy manufacturability, and light weight [1–3]. Among various polymer matrices, polyamide-imide (denoted as PAI) is of special significance for a wide range of lubrication coatings, due to its excellent mechanical properties, good thermal stability and chemical inertness, as well as high wear resistance [4, 5]. However, it needs to further improve the comprehensive properties of PAI coatings in order to ensure their safety under increasingly harsh service condition. Pointing to the abovementioned issue, some researchers have made attempts to introduce inorganic nanoparticles into PAI matrix, hoping to acquire PAI-based nanocomposites with improved overall performance [6]. Various inorganic nanoparticles such as carborundum nanoparticle [7, 8], titanium dioxide nanoparticle [9], aluminum oxide nanoparticle (Al2O3) [10], and carbon nanotube are considered to be promising in this respect. Silica nanoparticle is also promising, since it can be incorporated into PAI matrix via simple ultrasonic blending to afford functional silica/PAI composite films with greatly improved mechanical properties and thermal stability [11]. Moreover, hydrosilicate nanotubes are competitive in reducing the surface energy and increasing the hardness and wear resistance of PAI coatings [12]. However, inorganic nanoparticles with a large specific surface area and a high surface energy tend to agglomerate and possess poor compatibility with polymer matrix, which is unfavorable for their application in polymer matrix composites [13]. Therefore, some researchers are keeping eyes on organic–inorganic hybrid composites in order to integrate the high rigidity, good mechanical performance and high thermal stability of inorganic materials with the desired flexibility, ductility and processability of polymer materials [14–16]. In terms of the development of organic–inorganic hybrid composites, polyhedral oligomeric silsesquioxane (POSS) as an organic–inorganic hybrid nanofiller with a unique hollow cage structure and good molecule-regulation ability is worth special attention [17, 18]. This is because, on the one hand,
the inorganic framework of POSS, the Si–O-Si backbone, can impart admirable heat resistance and mechanical properties to hybrid materials [19–21]. On the other hand, the organic groups of POSS can be designed and manipulated to be either reactive or inert, in order to improve the comprehensive properties of organic–inorganic hybrid composites either via realizing the chemical bonding or via increasing the compatibility between silsesquioxane and polymer matrix [22, 23]. In addition, POSS can form different structures with polymer matrix, such as starshaped, beaded or three-dimensional cross-linked networks, which is also favorable for improving the overall properties of organic–inorganic hybrid composites [24]. In fact, various functionalized POSS fillers have been found to be contributive to the thermal stability and mechanical properties of epoxy resin (denoted as EP), phenolic resin and acrylic resin. For example, Zhang et al. [25] found that, as compared with EP, EP/NH2-POSS [NH2 refers to octa(3-amino propyl)] hybrid composites exhibit significantly improved compatibility, thermal stability and tensile strength. Yari et al. [26] reported that the introduction of octa-hydroxyl functionalized POSS to acrylic resin contributes to greatly increasing the hardness, crosslink density, and wear resistance of the hybrid composites. These researches remind us that NH2-POSS could be incorporated into PAI matrix, thereby shedding light on the development of PAI-based bonded solid lubricant coatings with significantly improved mechanical and tribological properties. In this study, therefore, we incorporate NH2-POSS into PAI and/or polytetrafluoroethylene (denoted as PTFE) in order to acquire PAI/PTFE-based bonded solid lubricant coatings with potential in aerospace and aviation engineering. This article reports the preparation of NH2-POSS/PAI/PTFE composite coatings and the evaluation of their tribological properties in relation to structure characterizations.
Experimental details Materials Analytically pure N, N-dimethylformamide (DMF), ethanol and hydrochloric acid were commercially obtained from East Instrument Chemical Glass Co., Ltd (Shanghai, China). PTFE powder (ground with a planetary ball mill; average particle size: 25 lm) and
J Mater Sci
PAI resin were provided by Shanghai Research Institute of Synthetic Resins (Shanghai, China). NH2POSS was synthesized at our laboratory by dehydration condensation reaction.
composites was determined with a DSC 200 PC differential scanning calorimeter (Netzsch Grinding & Dispersing, Germany, temperature range: 25–350 °C) under N2 atmosphere and a heating rate of 10 °C/ min.
Preparation of NH2-POSS/PAI coatings With the assistance of ultrasonic blending, NH2-POSS was added into PAI resin at a mass fraction of 3, 5, 7 and 9%, respectively, to afford NH2-POSS/PAI hybrid composites. The as-obtained NH2-POSS/PAI hybrid composites are denoted as C1, C2, C3 and C4, respectively, depending on the content of NH2-POSS. PAI designated as C0 was used for a comparative study. PTFE and NH2-POSS/PAI hybrid nanocomposites were mechanically mixed at pre-set mass fractions. Prior to spraying, the steel (AISI 1045 steel) substrate surfaces were roughened by sandblasting to a surface roughness (Ra) of 2.00 ± 0.20 lm and ultrasonically cleaned twice with acetone for 10 min, for the sake of improving the bonding strength of the coatings. Then, NH2-POSS/PAI/PTFE composites were sprayed onto the steel block (12.35 mm 9 12.35 mm 9 19 mm) with a spray gun operating with 0.2 MPa gas. After solvent evaporation, the assprayed coatings were cured at an electric oven to afford as-fabricated bonded solid lubricant coatings designated as C0–C4/PTFE. The thickness of the C0– C4/PTFE was measured to be 25–30 lm with a MINITEST 1100 microprocessor coating thickness gauge.
Molecular structure of NH2-POSS/PAI hybrid composites A proper amount of NH2-POSS/PAI hybrid composites was mixed with dried KBr pellets; and a Nicolet Avata360 Fourier transform infrared spectrometer (FTIR) was performed in a wavenumber range of 500–4000 cm-1 to determine the phase composition of the coatings. X-ray diffraction (XRD, Philips, Netherlands, Cu Ka radiation) patterns of NH2-POSS/PAI hybrid composites were recorded in a 2h range of 5°–60°. The thermogravimetric analysis (TGA) under N2 atmosphere and a heating rate of 10 °C/min were conducted in the temperature range of 25–800 °C with an STA 449 C analyzer (Netzsch Grinding & Dispersing, Germany). The glass transition temperature (Tg) of the NH2-POSS/PAI hybrid
Adhesion strength and mechanical properties of NH2-POSS/PI composite coatings The microhardness of NH2-POSS/PI composite coatings was measured with a microhardness tester (HXS-1000; Caikon, China) under an applied load of 10 N. The microhardness measurements were conducted at five different positions of each NH2-POSS/ PI composite coating, and the average of the five measurements is reported in this article. In the meantime, the pendulum hardness of NH2-POSS/PI composite coatings was determined with a pendulum hardness tester (PH-5856; BYK, German) within an angle range from 5° to 2°. According to Chinese National Standard GB/T 5210-2006 (pull-off test for adhesion determination of coating), the bonding strength of the NH2-POSS/PI composite coatings to steel substrate was determined with an Elcometer 506 Analogue & Digital Adhesion Tester (Elcometer, UK). The static water contact angles of the as-fabricated NH2-POSS/PI composite coatings were measured with an OCA15 contact angle goniometer (Dataphysics Company, Germany). With the assistance of sessile drop technique, 5 lL of ultrapure water (twice distilled) was dropped onto the surface of NH2-POSS/PI composite coatings. At least five repeat measurements were conducted for each NH2-POSS/PI composite coating, and the average of the repeat measurements is reported in this article. Moreover, a scanning electron microscope [SEM, JSM-5600LV, Japan; equipped with an energy dispersive spectrometer (EDS)] was performed to observe the morphology of C0–C4 coatings and the worn surface morphology of C0–C4/PTFE coatings.
Friction and wear test The friction and wear behavior of NH2-POSS/PAI hybrid coatings on AISI-1045 steel disks (12 mm 9 12 mm 9 19 mm) was evaluated with a ball-on-disk tribometer (CSM; Anton Paar, China) at room temperature. The stationary upper steel ball (SAE-52100, diameter: 6 mm) was driven to slide against the
J Mater Sci
lower rotary disk at an amplitude of 5 mm, a speed of 0.1 m/s and a load of 5 N for 27 min (referring to a sliding distance of 100 m). The wear volume of the NH2-POSS/PAI hybrid coatings was determined with a Micro-XAM-3D non-contact surface profiler (AEP, USA), and the wear rate was calculated as W = V/PL, where V is the wear volume loss (mm3) of the hybrid coatings in, P (N) is the applied load, and L (m) is the sliding distance. Three repeat tests were performed for each NH2-POSS/PAI hybrid coating; and the averages of the repeat tests are presented in this article.
Results and discussion Characterization of NH2-POSS/PAI hybrid composite coatings Figure 1 shows the FTIR spectra of PAI-based composite films with different contents of NH2-POSS. NH2-POSS shows obvious characteristic absorption peaks of Si–O-Si bond at 1108 cm-1 and the absorption peaks of Si–C bond and amino group at 1275 and 3444 cm-1, respectively [27]. Pure PAI shows the characteristic absorbance bands of amino acid group at 3200–3500 cm-1, the absorbance band of C=O bond in imide ring around 1720 and 1779 cm-1, and that of amide C-N bond at 1378 cm-1 [28]. During the imidization process, amino acids react with carboxyl groups to form secondary amides with a single absorbance peak at 3444 cm-1. With the introduction
Figure 1 FTIR spectra of PAI-based composite with different contents of NH2-POSS.
of POSS, the amino groups in both POSS and PAI react with carboxyl groups to generate primary amines with characteristic absorbance bands at 3500 and 3400 cm-1 as well as a bimodal absorbance peak whose intensity rises with the increase in POSS content. In the meantime, the introduction of POSS leads to a significant increase in the intensity of the absorbance band of primary amine N–H bond at 1617 cm-1; and with the increase in POSS content, the intensity of the absorbance peak of C-H bond near 2950 cm-1 also increases in association with the appearance of the strong absorbance peak of Si–C bond [3, 16]. Figure 2 shows the XRD spectra of NH2-POSS, PAI and 7% NH2-POSS/PAI composite coating. Pure NH2-POSS shows a distinct diffraction peak at 2h = 9.8°, and it corresponds to a d-spacing of 1.23 nm (calculated by Bragg equation), identical to that reported in literature. Besides, both pure PAI and NH2-POSS/PAI composite coating exhibit similar broad peaks at 2h = 19°, corresponding d-spacing is 0.73 nm. Moreover, the NH2-POSS/PAI composite coating shows the characteristic peaks of NH2-POSS near the broad peak of PAI, which indicates that
Figure 2 XRD spectra of NH2-POSS composite, PAI and 7% NH2-POSS/PAI composite coating.
J Mater Sci
NH2-POSS still retains a nanosize in the hybrid polymer and exhibits a uniform dispersion in the polymer matrix [29–31]. Figures 3 and 4 show the TGA curves and DSC (differential scanning calorimetry) curves of PAI and NH2-POSS/PAI composites. It can be seen that NH2POSS begins to decompose and lose weight at 240 °C (Fig. 3a), lower than the decomposition temperature of neat PAI. This demonstrates that the introduction of NH2-POSS has an insignificant effect on the thermal decomposition behavior of neat PAI with good thermal stability. Besides, as shown in Fig. 3b, 7% NH2-POSS/PAI composite exhibits better thermal stability than the PAI-based composites containing 3, 5, and 9% NH2-POSS. The increase in the thermal stability of NH2-POSS/PAI composites is attributed to their cross-linked network and the high bonding energy of Si–O-Si, which may hinder the movement of the polymer molecular chains and slow down the decomposition [32]. The glass transition temperature (Tg) of PAI and NH2-POSS/PAI composites can be obtained from the DSC curves shown in Fig. 4. The measured DSC thermograms display only one single Tg in the range of 220–250 °C. The Tg of pure PAI is relatively low (223 °C) and that of the hybrid composites increases with the increase in NH2-POSS content. Besides, the introduction of a relatively low content of 3% NH2-POSS leads to a significant increase in the Tg of the polymer-based composites. The introduction of over 3% NH2-POSS, however,
Figure 4 DSC curves of PAI-based composites with contents of NH2-POSS.
contributes to slightly increasing the Tg values; and in particular, the 7% NH2-POSS/PAI composite has the highest Tg. The increase in the Tg of NH2-POSS/PAI composites could be attributed to the unique threedimensional hollow cage structure of NH2-POSS and the high cross-linking density of the hybrid polymers. Therefore, it can be inferred that the maximum crosslinking density of the PAI-based composites is achieved at a NH2-POSS content of 7%. However, when the content of NH2-POSS is above 7%, the large steric hindrance of NH2-POSS molecules would cause an increase in the activation energy in association with the agglomeration of NH2-POSS molecules in
Figure 3 TGA curves of NH2-POSS and PAI-based composites in the temperature ranges of a 25–800 °C and b 25–500 °C.
J Mater Sci
the polymer matrix, thereby damaging the crosslinking density and lowering Tg [29, 33].
Surface properties and adhesion strength of PAI-based composite coatings The microhardness and pendulum hardness of PAI and NH2-POSS/PAI composite coatings are shown in Fig. 5. The microhardness of C0 coating (pure PAI) is about 23 HV, and the introduction of NH2-POSS leads to a significant increase in the microhardness of NH2-POSS/PAI composite coatings. In the meantime, the microhardness of the composite coatings increases with the increase in NH2-POSS content, and coating C4 has the highest hardness of 32 HV. Similar phenomenon is also observed with the pendulum hardness. In general, the addition of NH2-POSS particles contributes to significantly increasing the hardness of PAI-based composite coatings. This is because NH2-POSS contains the inorganic framework consisting of the hollow structure of Si–O–Si bond and the active functional groups as well, and both the inorganic framework and active functional groups are favorable for increasing the cross-linking density of the polymer matrix composites [34]. Figure 6 shows the bonding strength of various PAI-based composite coatings. As compared with C0, coatings C1–C4 possess a higher bonding strength; and in particular, the bonding strength of PAI-based composite coatings increases with the increase in NH2-POSS content. This is because, along with the
Figure 5 Microhardness and pendulum hardness of coatings C0, C1, C2, C3 and C4.
Figure 6 The bonding strength of coatings C0, C1, C2, C3 and C4.
organic–inorganic hybridization involving the connection of the amino groups with inorganic framework, the cross-linking density and interfacial bonding between the organic and inorganic species are obviously increased [35, 36]. However, when the content of NH2-POSS is above 7%, the NH2-POSS molecules in the PAI matrix would tend to agglomerate and the steric hindrance would rise, thereby decreasing the cross-linking density and bonding strength of the PAI-based composite coatings [34]. The SEM morphology and surface roughness of various PAI-based composite coatings are given in Fig. 7. It can be seen that the surface of coating C0 (pure PAI) is quite smooth; and the surfaces of the hybrid coatings C1–C4 become increasingly rough with the increase in NH2-POSS content. This well corresponds to relevant three-dimensional (denoted as 3D) profiles of the composite coatings. Moreover, when the content of NH2-POSS reaches 9%, the convex structure on the surface of coating C4 is obviously enlarged. The increase in the surface roughness of the PAI-based composite coatings containing an increased content of NH2-POSS content could be due to the surface migration effect and surface enrichment of NH2-POSS. In other words, the high concentration of NH2-POSS undergoes obvious phase separation on the surface of the composite coatings, thereby resulting in an increase in the surface roughness [6, 37].
J Mater Sci
Figure 7 SEM micrographs and 3D profile of coatings C0, C1, C2, C3 and C4.
J Mater Sci
Figure 8 Water contact angle of coatings C0, C1, C2, C3 and C4.
Figure 8 shows the water contact angles of various PAI-based composites. Coating C0 has a water contact angle of less than 90°, which means that pure PAI coating exhibits a certain degree of wettability. After the introduction of NH2-POSS, the composite coatings C1–C4 exhibit contact angles of 97°, 103°, 108° and 112°, respectively, showing a certain degree of hydrophobicity. Besides, the water contact angles of the PAI-based composite coatings increase with the increase in NH2-POSS content, which is in good agreement with the increases in the surface roughness and surface energy of the composite coatings therewith [38].
Friction and wear behavior of NH2-POSS/ PAI/PTFE hybrid coatings The friction coefficient-sliding distance curves of various NH2-POSS/PAI/PTFE hybrid coatings are shown in Fig. 9. As compared with NH2-POSS/PAI/ PTFE hybrid coatings containing different contents of NH2-POSS, C0/PTFE coating possesses a relatively high friction coefficient of 0.073. Namely, coating C1/ PTFE with 3% NH2-POSS exhibits a slightly decreased friction coefficient of 0.066; and coatings C2/PTFE, C3/PTFE and C4/PTFE with an increased content (5, 7, and 9%) of NH2-POSS exhibit relatively lowered friction coefficients of 0.065, 0.057, and 0.063. Figure 10 shows the 3D profiles of worn surfaces of coatings C0/PTFE, C1/PTFE, C2/PTFE, C3/PTFE,
Figure 9 Friction coefficient-sliding distance curves of coatings C0/PTFE, C1/PTFE, C2/PTFE, C3/PTFE and C4/PTFE.
and C4/PTFE and their two-dimensional profiles of sectional wear tracks. It can be seen that the wear track of C0/PTFE coating is the deepest and widest (Fig. 10a), which corresponds to its serious wear. With the increase in NH2-POSS content, the wear track becomes shallower and narrower, which indicates that the introduction of NH2-POSS markedly contributes to improving the wear resistance of PAI/ PTFE hybrid coating. This is also supported by the two-dimensional cross-sectional view of the wear tracks (Fig. 10b). The average friction coefficients and wear rates of NH2-POSS/PAI/PTFE coatings are shown in Fig. 11. The wear rate of the coatings decreases obviously with the increase in NH2-POSS content. Particularly, coating C3 with 7% NH2-POSS exhibits the lowest wear rate. Figure 12 shows the SEM images of the worn surfaces of C0/PTFE, C1/PTFE, C2/PTFE, C3/PTFE and C4/PTFE coatings. It can be seen that C0/PTFE coating is dominated adhesion wear, and C0–C4/ PTFE hybrid coatings are dominated by significantly reduced adhesion wear. This could be related to the decrease in the surface energy and interface adsorption capacity of the PAI/PTFE-matrix composite coatings upon the introduction of NH2-POSS [39]. Besides, the introduction of NH2-POSS also contributes to increasing the cross-linking density and hardness of PAI/PTFE-matrix composite coatings, thereby adding to the wear resistance of the coatings.
J Mater Sci
Figure 10 Three-dimensional profiles of a worn surfaces of coatings C0/PTFE, C1/PTFE, C2/PTFE, C3/PTFE, and C4/PTFE and twodimensional profiles of b the sectional wear tracks.
Figure 11 Average friction coefficients and wear rates of coatings C0/PTFE, C1/PTFE, C2/PTFE, C3/PTFE, and C4/PTFE.
Conclusions A series of NH2-POSS/PAI hybrid nanocomposites with well-defined structure are prepared with the assistance of ultrasonic blending. Structure
characterizations by FTIR and XRD indicate that the amino groups of NH2-POSS nanoparticles are chemically bonded to the molecular chains of PAI. The hollow structure of NH2-POSS with Si–O-Si bond as the inorganic framework, in association with the increase in the cross-linking density of the hybrid composites upon the addition of NH2-POSS, contributes to increasing the thermal stability, microhardness and bonding strength of NH2POSS/PAI hybrid composites. Moreover, the addition of NH2-POSS contributes to significantly decreasing the surface energy of NH2-POSS/PAI/ PTFE composite coatings, thereby reducing the friction and wear of the PAI/PTFE-matrix composite coatings (Fig. 13). Particularly, NH2-POSS/ PAI/PTFE composite coating containing 7% NH2POSS exhibits the lowest friction coefficient and wear rate among various tested coatings, displaying promising potential as a high-performance bonded solid lubricant coating.
J Mater Sci
Figure 12 SEM images of worn surfaces of C0/PTFE, C1/PTFE, C2/PTFE, C3/PTFE and C4/PTFE coatings.
Figure 13 Synthesis route of PAI and tribological mechanism of NH2-POSS/PAI/PTFE lubrication coatings.
Acknowledgements
References
The funding from the National Natural Science Foundation of China (Grant Nos. 51775533 and U1637204) is gratefully acknowledged. The authors also wish to express their gratitude to Mr Yuan (Dongming Yuan, Beijing University of Chemical Technology) for providing linguistic assistance during the preparation of this manuscript.
[1]
[2]
Demian C, Liao H, Lachat R, Costil S (2013) Investigation of surface properties and mechanical and tribological behaviors of polyimide based composite coatings. Surf Coat Technol 235(12):603–610 Jia JH, Zhou HD, Gao SQ, Chen JM (2003) A comparative investigation of the friction and wear behavior of polyimide composites under dry sliding and water-lubricated condition. Mater Sci Eng A 356(1–2):48–53
J Mater Sci
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
Devaraju S, Vengatesan MR, Alagar M (2011) Studies on thermal and dielectric properties of ether linked cyclohexyl diamine (ELCD)-based polyimide POSS nanocomposites (POSS-PI). High Perform Polym 23(2):99–111 Mehdipour-Ataei S, Sarrafi Y, Hatami M (2004) Novel thermally stable polyimides based on flexible diamine: synthesis, characterization, and properties. Eur Polym J 40(9):2009–2015 Li Z, Song H, He M, Liu J, Yang S (2012) Atomic oxygenresistant and transparent polyimide coatings from [3,5-bis(3aminophenoxy)phenyl]diphenylphosphine oxide and aromatic dianhydrides: Preparation and characterization. Prog Org Coat 75(1–2):49–58 Sadhasivam B, Muthusamy S (2016) Thermal and dielectric properties of newly developed L-tryptophan-based optically active polyimide and its POSS nanocomposites. Des Monomers Polym 19(3):1–12 Basavarajappa S, Arun KV, Davim JP (2009) Effect of filler materials on dry sliding wear behavior of polymer matrix composites—a taguchi approach. J Miner Mater Charact Eng 08(5):379–391 Suresha B, Chandramohan G, Sadananda Rao PR, Sampathkumaran P, Seetharamu S (2007) Influence of SiC filler on mechanical and tribological behavior of glass fabric reinforced epoxy composite systems. J Reinf Plast Compos 26(6):565–578 Boyadzhiev S, Georgieva V, Rassovska M Characterization of reactive sputtered TiO2 thin films for gas sensor applications. https://doi.org/10.1088/1742-6596/253/1/012040 Cai H, Yan F, Xue Q, Liu W (2003) Investigation of tribological properties of Al2O3–polyimide nanocomposites. Polym Test 22(8):875–882 Ma X, Lee NH, Oh HJ, Hwang JS, Kim SJ (2010) Preparation and characterization of silica/polyamide-imide nanocomposite thin films. Nanoscale Res Lett 5(11):1846–1851 Gubanova G, Kononova S, Bronnikov S, Romashkova K, Sukhanova T, Korytkova E, Timpu D, Cristea M, Harabagiu V (2014) Nanocomposites based on aromatic polyamideimide and magnesium hydrosilicate nanotubes. J Macromol Sci B 53(4):555–567 Raftopoulos KN, Koutsoumpis S, Jancia M, Lewicki JP, Kyriakos K, Mason HE, Harley SJ, Hebda E, Papadakis CM, Pielichowski K (2015) Reduced phase separation and slowing of dynamics in polyurethanes with three-dimensional POSS-based cross-linking moieties. Macromolecules 48(5):1429–1441 Sanchez C, Ribot F, Rozes L, Alonso B (1999) Design of hybrid organic-inorganic nanocomposites synthesized via sol–gel chemistry. J Mater Chem 9(1):1007–1047
[15] Novak BM (1993) Hybrid nanocomposite materials—between inorganic glasses and organic polymers. Adv Mater 5(6):422–433 [16] Chandramohan A, Nagendiran S, Alagar M (2012) Synthesis and characterization of polyhedral oligomeric silsesquioxane–siloxane-modified polyimide hybrid nanocomposites. J Compos Mater 46(7):773–781 [17] Li G, Wang L, Ni H, Pittman CU (2001) Polyhedral oligomeric silsesquioxane (POSS) polymers and copolymers: a review. J Inorg Organomet Polym 11(3):123–154 [18] Leu CM, Yaote Chang A, Wei KH (2003) Synthesis and dielectric properties of polyimide-tethered polyhedral oligomeric silsesquioxane (POSS) nanocomposites via POSSdiamine. Chem Mater 15(11):2261–2265 [19] Wright ME, Schorzman DA, Feher FJ, Jin R (2003) Synthesis and thermal curing of aryl-ethynyl-terminated coPOSS imide oligomers: new inorganic/organic hybrid resins. Chem Mater 15(1):264–268 [20] Huang J, He C, Xiao Y, Mya KY, Dai J, Siow YP (2003) Polyimide/POSS nanocomposites: interfacial interaction, thermal properties and mechanical properties. Polymer 44(16):4491–4499 [21] Zeng L, Liang G, Gu A, Yuan L, Zhuo D, Hu JT (2012) High performance hybrids based on a novel incompletely condensed polyhedral oligomeric silsesquioxane and bismaleimide resin with improved thermal and dielectric properties. J Mater Sci 47(6):2548–2558. https://doi.org/10. 1007/s10853-011-6078-3 [22] Chiou CW, Lin YC, Wang L, Hirano C, Suzuki Y, Hayakawa T, Kuo SW (2014) Strong screening effect of polyhedral oligomeric silsesquioxanes (POSS) nanoparticles on hydrogen bonded polymer blends. Polymers 6(3):926–948 [23] Zhang W, Mu¨ller AHE (2013) Architecture, self-assembly and properties of well-defined hybrid polymers based on polyhedral oligomeric silsesquioxane (POSS). Prog Polym Sci 38(8):1121–1162 [24] Gong C, Liang Y, Qi Z, Li H, Wu Z, Zhang Z, Zhang S, Zhang X, Li Y (2015) Solution processable octa(aminophenyl)silsesquioxane covalently cross-linked sulfonated polyimides for proton exchange membranes. J Membr Sci 476(476):364–372 [25] Zhang Z, Liang G, Wang J, Ren P (2007) Epoxy/POSS organic–inorganic hybrids: viscoelastic, mechanical properties and micromorphologies. Polym Compos 28(2):175–179 [26] Yari H, Mohseni M, Messori M, Ranjbar Z (2014) Tribological properties and scratch healing of a typical automotive nano clearcoat modified by a polyhedral oligomeric silsesquioxane compound. Eur Polymer J 60:79–91 [27] Song G, Li X, Jiang Q, Mu JX, Jiang Z (2015) A novel structural polyimide material with phosphorus and POSS
J Mater Sci
[28]
[29]
[30]
[31]
[32]
[33]
[34]
synergistic for atomic oxygen resistance. Rsc Adv 5(16):11980–11988 Sec¸kin T, Ko¨ytepe S, Adıgu¨zel HI˙ (2008) Molecular design of POSS core star polyimides as a route to low-j dielectric materials. Mater Chem Phys 112(3):1040–1046 Sethuraman K, Prabunathan P, Alagar M (2014) Thermomechanical and surface properties of POSS reinforced structurally different diamine cured epoxy nanocomposites. Rsc Adv 4(85):45433–45441 Chen-yi Wang, Wen-tao Chen, Chang Xiao-yan, Zhao Jian (2016) Fluorinated polyimide/POSS hybrid polymers with high solubility and low dielectric constant. Chin J Polym Sci 34(11):1363–1372 Ferna´ndez MD, Ferna´ndez MJ, Cobos M (2016) Effect of polyhedral oligomeric silsesquioxane (POSS) derivative on the morphology, thermal, mechanical and surface properties of poly(lactic acid)-based nanocomposites. J Mater Sci 51(7):3628–3642. https://doi.org/10.1007/s10853-015-96865 Wu YW, Ye MF, Zhang WC, Yang RJ (2017) Polyimide aerogels crosslinked through cyclic ladder-like and cage polyamine functionalized polysilsesquioxanes. J Appl Polym Sci 134(37):45296. https://doi.org/10.1002/APP.45296 Pistor V, Puziski L, Zattera AJ (2015) Effect of glycidylisobutyl–POSS on the thermal degradation of the epoxy resin. J Mater Sci 50(10):3697–3705. https://doi.org/10. 1007/s10853-015-8930-3 Wang X, Hu Y, Song L, Xing W, Lu H, Lv P, Jie G (2011) UV-curable waterborne polyurethane acrylate modified with
[35]
[36]
[37]
[38]
[39]
octavinyl POSS for weatherable coating applications. J Polym Res 18(4):721–729 Aparicio M, Jitianu A, Rodriguez G, Al-Marzoki K, Jitianu M, Mosa J, Klein LC (2017) Thickness-properties synergy in organic–inorganic consolidated melting-gel coatings for protection of 304 stainless steel in NaCl solutions. Surf Coat Technol 315:426–435 Lukauskait_e R, Cˇernasˇe_ jus O, Sˇkamat J, Zabulionis D, Stonys R, Kalpokait_e-Dicˇkuvien_e R, Antonovicˇ V (2017) The effect of Al Mg substrate preparation on the adhesion strength of plasma sprayed Ni Al coatings. Surf Coat Technol 316:93–103. https://doi.org/10.1016/j.surfcoat. 2017.02.069 Liao W, Huang X, Ye L, Lan S, Fan H (2016) Synthesis of composite latexes of polyhedral oligomeric silsesquioxane and fluorine containing poly(styrene–acrylate) by emulsion copolymerization. J Appl Polym Sci. https://doi.org/10.1002/ APP.43455 Chen L, He C, Huang Y, Huang J, Zhang Y, Gao Y (2016) POSS-based fluorinated azobenzene-containing polymers: photo-responsive behavior and evaluation of water repellency. J Appl Polym Sci. https://doi.org/10.1002/app.43540 Pan Z, Wang T, Chen L, Idziak S, Huang Z, Zhao B (2017) Effects of rare earth oxide additive on surface and tribological properties of polyimide composites. Appl Surf Sci 416:536–546
