Polymer Nanocomposite Paper with High

Subscriber access provided by La Trobe University Library

Article

Bioinspired Graphene Oxide/Polymer Nanocomposite paper with high strength, toughness, and dielectric constant Shiqiang Song, Yinghao Zhai, and Yong Zhang ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.6b08606 • Publication Date (Web): 26 Oct 2016 Downloaded from http://pubs.acs.org on October 26, 2016

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

ACS Applied Materials & Interfaces is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 24

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

Bioinspired Graphene Oxide/Polymer Nanocomposite paper with high strength, toughness, and dielectric constant Shiqiang Song a, Yinghao Zhai a, Yong Zhang a,* a

School of Chemistry and Chemical Engineering, State Key Laboratory for Metal Matrix Composite Materials, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China.

Abstract: Graphene/graphene oxide (GO)-based paper is attracting great interest owing to its multiple functionalities. In this study, we successfully synthesized a triblock copolymer by atom transfer radical polymerization (ATRP) method in terms of molecular design. The copolymer was comprised of polydimethylsiloxane (PDMS) and poly (glycidyl methacrylate) (PGMA) segments. To the copolymer, the PDMS segments provided flexible characteristic and the PGMA segments provided reactive groups and adhesiveness. Due to the above characteristics, the copolymer was used as an adhesive between the adjacent graphene oxide (GO) nanosheets for fabrication of GO/PDMS-PGMA papers. The papers showed a good combination of high tensile strength and toughness. The tensile strength and toughness of GO/PDMS-PGMA (85/15) paper reached as high as 309 MPa and 6.55 MJ·m-3, which were 3.4 and 8.2 times higher than that of pure GO paper. Furthermore, the papers also had high dielectric constant, which may enable this kind of materials to be used in electronic and engineering fields. Keywords: graphene oxide, ATRP, graphene oxide-based paper, mechanical properties, dielectric constant

1. Introduction Graphene oxide (GO) with many functional groups on its surface is an ideal candidate for the fabrication of artificial nacre. The GO-based nacres have shown a wide range of application for biological scaffold,1-2 energy storage,3 drug delivery,4 high-power anodes,5 supercapacitors,6 etc. Recently, many reports on graphene or GO-based nanocomposites have been reported. As revealed in literature,7 the special layered structure and the strong interfacial interaction of the graphene or GO-based nacres are responsible for their

ACS Paragon Plus Environment


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

unique mechanical performance. Two dimensional graphene or GO sheets served as the layered structure at nanoscale have ultrahigh tensile strength and modulus, and the interaction among the graphene or GO sheets has become the strategic point during the construction of graphene or GO-based nacres. Graphene or GO-based nacres are mainly constructed by three approaches, i.e., ionic bonding, covalent bonding and hydrogen bonding. Firstly, metal ions including Mg2+ and Ca2+ were introduced into the interlayer of GO, which increased the tensile strength and Young’s modulus of nacrces.8 Secondly, covalent bonding was much more reliable between GO sheets and adhesives, and it could avoid the easy destruction in solution or change of pH value for ionic bonding. Glutaraldehyde as a linear small molecule was used to covalently crosslinking GO sheets,9 and 10,12-pentacosadiyn-1-ol as a long chain linear molecule was used to construct the covalent bonding with GO nanosheets.10 Polyallylamine as a polymer was used to prepare covalent bonded GO composites.11 Thirdly, H-bonding was used as a typical non-covalent crosslinking method to prepare GO composites. Compared with covalent bonding, H-bonding is more easily formed between GO and polymers or small molecules. Ruoff et al. fabricated GO-based nacres via hydrogen bonding between colloidal and the GO nanosheets.12 Both poly (vinyl alcohol) and poly (methyl methacrylate) (PMMA) were used to prepare GO composites through hydrogen bonding.13 The three approaches can be used to fabricating graphene or GO nacres with good mechanical properties. However, despite taking into account the three approaches and key points during the construction of the graphene or GO nacres, the obtained nacres often showed improvement for a single performance rather than the comprehensive performance. Many efforts have focused on the interactions among the graphene or GO sheets, and the characteristics of polymers in the interlayer of GO have not drawn enough attention. In fact, the polymers played an important role of obtaining the comprehensive properties of graphene or GO nacres. For example, the GO papers used Mg2+ and Ca2+ as crosslinking agents showed increased tensile strength, but the resultant composites often exhibited lower toughness.8 A linear copolymer sodium alginate (SA) was used as a crosslinking agent for GO to get composite papers, and the composite papers showed higher toughness. Chitosan (CS), a copolymer generally obtained by deacetylation of chitin, showed high toughness. When CS was introduced into GO interlayers, the obtained GO/CS composites showed not only increased tensile strength but also higher toughness.14 Therefore, in order to construct graphene/GO-based films with combination of high strength, flexibility, and other


Page 2 of 24

Page 3 of 24

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


properties, it is necessary to consider the properties of polymers as crosslinking agents in the process of the construction of graphene or GO nacres. In this paper, we successfully synthesized a triblock copolymer which consisted of two different repeating units in terms of molecular design. The “soft segment” polydimethylsiloxane (PDMS) could provide the copolymer with flexible characteristic and the “active segment” poly(glycidyl methacrylate) (PGMA) could provide the copolymer with reactive groups. The epoxy groups in side chains of PDMS-PGMA could form H-bonding with GO sheets. Based on the above consideration, we prepared a GO based nacre using PDMS-PGMA as an adhesive to crosslink GO sheets by a vacuum-assisted self-assembly (VASA) method. The resultant GO/PDMS-PGMA composites papers exhibited high tensile strength and high toughness, which were many-folds higher than those of previous materials crosslinked by H-bonding. GO/PDMS-PGMA papers also showed lower dielectric loss and higher dielectric constant. Because of the combination of exceptional mechanical strength and dielectric properties, the GO/PDMS-PGMA papers showed potential in wide applications such as electronic and engineering materials.

2. Experimental 2.1. Materials Flake graphite (99.8%) with average particle size of 4.5 μm was purchased from Alfa Aesar (China) Chemical Co., Ltd. Glycidyl methacrylate (GMA, 97%) was purchased from J&K chemical Co. and passed through a basic alumina column before used. Hydroxyl terminated polydimethylsiloxane (OH-PDMS-OH) with Mw of 4200 was obtained from Sigma Aldrich and used as received. All the other chemicals were used as received unless otherwise noted. 2.2. Characterization FTIR spectra were obtained on a Perkin-Elmer Paragon 1000PC spectrometer as the background from 400–4000 cm-1. XPS measurements were carried out on an RBD upgraded PHI-5000C ESCA system (Perkin-Elmer) with Al Kα radiation (hυ =1486 eV). X-ray diffraction (XRD) were measured on a BRUKER D8 ADVANCE using Cu Kα radiation (λ = 1.54 Å). Mn, Mw and PDI (Mw/Mn) of the polymer were measured with GPC (HLC-8320GPC, TOSOH, Japan), with poly(methyl methacrylate) as a reference standard and N,N-dimethylformamide (DMF) as an eluent. 1H-NMR (400



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

MHz) spectra were measured using a Bruker spectrometer in CDCl3 at ambient temperature. Thermal stabilities and the copolymer content in composites papers were measured via thermogravimetric analysis (TGA) in nitrogen with a TA Instruments model Q2000 at a heating rate of 20 °C min-1. Rheological behavior was measured using a stress-controlled AR G2 rheometer (TA Instruments) with 25 mm parallel plate geometry and a gap of 0.9 mm in DMF. The tensile properties of composite papers were measured with an Instron 4465 tensile machine at room temperature at a crosshead speed of 4 mm/min and their initial gauge length was 20 mm. The samples were cut into strips of 4mm width and five strips were measured for each sample. Atomic force microscopic (AFM) analysis of the composites surface was conducted on a Nanoscope IIIa scanning probe microscope (Digital Instruments, Santa Barbara, CA) in tapping mode under ambient conditions. The tensile fracture surfaces morphology was characterized by scanning electron microscopy (SEM) (Nova NanoSEM 450). The broadband dielectric properties were measured using an impedance analyzer (Aglient 4294A) in the frequency range 10 to 107 Hz at ambient temperature. 2.3. Synthesis of PDMS-PGMA triblock copolymer by ATRP A macroinitiator (Br-PDMS-Br) was prepared according to the previous literatures.1516

Hydroxyl terminated Polydimethylsiloxane (32.8 g, 8 mmol) and triethylamine

(1.72 g, 17 mmol) were dissolved in 250 ml anhydrous tetrahydrogen furan (THF) in an ice bath for 30 min, and 2-bromoisobutyryl bromide (3.91 g, 17 mmol) was dropwise added under stirring. After stirring for 12 h at room temperature, triethylamine salt as a by-product was filtered from the solution, and the resultant filtrate was heated under vacuum to evaporate THF solvent and an oil product was obtained. The oil was re-dissolved in dichloromethane (200 ml) and extracted three times with saturated sodium bicarbonate solution (300 ml). The organic layer was separated and dried with anhydrous magnesium sulfate, filtered, and concentrated to obtain 30.7 g liquid PDMS macroinitiator (Br-PDMS-Br) with slight yellow color (yield 93.6%). 1H NMR (400 MHz, CDCl3), δ (ppm): 0.079 (s, 6H, Si(CH3)2), 1.96 (s, 6H, BrC(CH3)2). IR (KBr; cm-1): 2963, 2905 (C-H; s), 1260 (Si-C, s), 1094, 1020 (SiO-Si, s), 800(Si-C, δ). A triblock copolymer was prepared through atom transfer radical polymerization (ATRP) using Br-PDMS-Br as macroinitiator. GMA (5.7 g, 40 mmol), PMDETA (17.3 mg, 0.1 mmol), Br-PDMS-Br (0.42 g, 0.1 mmol) and anisole (15 mL) were


Page 4 of 24

Page 5 of 24

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


placed in a Schlenk tube and purged in N2 for 40 min. Cu(I)Br (14.4 mg, 0.1mmol) was added and nitrogen purging was continued for another 5 min. The polymerization was heated to 60 °C for 6 h and then exposed to air to stop the reaction. The reaction mixture was precipitated in methanol, filtered and dried. The precipitate as a crude product was further diluted with CH2Cl2, passed through an alumina column to remove the catalyst, and re-precipitated in methanol to give 2.6 g PGMA-b-PDMS-bPGMA triblock copolymer. 1H NMR (400 MHz, CDCl3), δ (ppm): 0.1 (s, 6H, Si(CH3)2), 0.94-1.15 (m, 3H, CCH3 ), 1.90-1.97 (m, 2H, CH2CCH3), 2.64 (broad signal, 2H, COOCH2CHCH2O), 2.84 (broad signal, 2H, COOCH2CHCH2O), 3.24 (broad signal, 1H, CH2CHCH2O), 3.83 (broad signal, 2H, COOCH2), 4.28 (broad signal, 2H, COOCH2); GPC (DMF): Mn=46500, Mw=63300, PDI (Mw/Mn)=1.36. 2.4. Fabrication of GO, PDMS-PGMA and GO/PDMS-PGMA composite Papers Graphene oxide (GO) was prepared according to a previous study.17 The corresponding characterization of GO can be seen in Figure S1 (Supplementary information). The GO dispersion (1 mg ml-1) in DMF was obtained after ultrasound for 60 min. GO/PDMS-PGMA composite films were obtained by the method of VASA. In briefly, a certain amount of PDMS-PGMA was mixed with a colloidal GO dispersion (1 mg ml-1), which was further ultrasound for 60 min and stirred 48 h until a homogeneous dispersion of GO/PDMS-PGMA was obtained. The dispersion was filtered through a polypropylene filter membrane (diameter: 47 mm; pore size: 0.22μm), dried in air until a piece of GO/PDMS-PGMA composite film can be peeled off. A series of GO/PDMS-PGMA films with different content of PDMS-PGMA (0~50%) could be obtained by the above method. A PDMS-PGMA triblock copolymer film was prepared by casting a 5% copolymer DMF solution (20 ml) a Teflon beaker (42-mm diameter). The film was placed in a fume hood for 4 days at ambient temperature before heating to 100 °C to remove all the solvents under vacuum.



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Figure 1. Schematic illustration of the preparation process of GO/PDMS-PGMA composite paper (a) The paper was achieved through mixing GO solution with PDMS-PGMA triblock copolymer (up), cross-section and vacuum filtrating (down). (b) Photograph of GO-20 and a strip of bended GO-20. (c-d) The front (c) and side (d) view fracture morphology of GO-20 paper.

3. Results and discussion The two dimensional GO nanosheets contain many oxygen-containing functional groups such as epoxy groups, carboxyl and carbonyl moieties and hydroxyl groups. The oxygen-containing functional groups on the GO sheets could easily form rich hydrogen bonds with the intercalated molecules or polymers.18-19 Based on this, Figure 1 illustrates of the preparation process of the GO/PDMS-PGMA papers. Firstly


Page 6 of 24

Page 7 of 24

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


GO sheets were fully exfoliated in DMF to form GO suspension, and then PDMSPGMA was added. The resultant GO/PDMS-PGMA dispersion was ultrasound treated and vigorously stirred for homogeneous morphology (Figure 1a up). The suspension was filtrated through a membrane. Although at the beginning a few copolymers passed through the membrane, most copolymers were hindered by the deposition of GO sheets. A series of GO/PDMS-PGMA composites with different of PDMS-PGMA were prepared and named as GO-7.5, GO-15, GO-20, GO-30 and GO-50 according to PDMS-PGMA content. As shown in Figure S2 and Table S1, the exact content PDMS-PGMA in GO composites was measured by TGA. The filtration resulted in homogeneous deposition of the GO sheets, with copolymer chains crosslinked between them (Figure 1a down), forming a GO/PDMS-PGMA paper (Figure 1b). 3.1. Interaction of GO and PDMS-PGMA In order to understand the interaction of GO and PDMS-PGMA, FTIR was used to characterize the GO, PDMS-PGMA and GO/PDMS-PGMA papers (Figure 2). From the spectra of GO and PDMS-PGMA, the oxygen-containing functional groups of GO can be readily identified, while the peak of epoxy (C-O-C) of PDMS-PGMA is at 910.20 It is worth noting that the peaks of Si-O-Si are small due to low content of middle PDMS block in copolymer. After the PDMS-PGMA was added into GO, some changes in the peaks of FTIR spectra (Figure 2a) took place in the composite papers. The peak at 910 cm-1 attributed to the epoxy (C-O-C) group of PDMS-PGMA down-shifted to 895 cm-1 and the peak at 3000-3500 cm-1 responding to the hydroxyl group of GO shifted to the lower wavenumbers or even weakened and disappeared. Meanwhile, the peaks of carbonyl (C=O, 1724 cm-1) and alkoxy (C-O, 1260 cm-1) of PDMS-PGMA showed the gradually decreased intensities with increasing GO content, and down-shifted to 1716 cm-1 and 1244 cm-1 at the GO content of 92.5%. The down-shift of the peaks of epoxy groups and hydroxyl groups, as well as the decreased intensities of the peak of carbonyl and alkoxy groups are usually considered as the evidence of hydrogen bonding.21-22 Therefore, the peak changes appeared in Figure 2(a) indicate that PDMS-PGMA is attached to GO sheets and associated with the strong interaction (hydrogen bonds) between PDMS-PGMA and GO.



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Figure 2. (a) FT-IR spectra of GO, PDMS-PGMA and GO/PDMS-PGMA nanocomposite films (b) Deconvoluted C1s XPS spectra of GO, PDMS-PGMA and GO/PDMS-PGMA composite films (GO-20)


Page 8 of 24

Page 9 of 24

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 3. (a) Rheological behavior of GO and GO-50 DMF solutions (1 mg/ml): the strain scanning. (b) XRD patterns of GO, PDMS-PGMA and GO/PDMS-PGMA composite papers. (c) Plot of interlayer spacing as a function of GO content.



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

XPS was used to probe the interaction between GO and PDMS-PGMA. The highresolution C1s XPS of GO spectra (Figure 2b) with five signals, namely C=C/C-C (284.8 eV), C-OH (285.5 eV), C-O-C (287.1 eV), C=O (287.8 eV) and O-C=O (288.7 eV) are in agreement with the report in the literature.23-24 While the XPS of PDMSPGMA (Figure S3) shows three signals corresponding to C, O, and Si, and five peaks appearing at 284.2, 284.8, 286.7, 287.6, 289.0 eV could be ascribed to C-Si, C=C/CC, C-O-C, C=O, and O-C=O groups, respectively (Figure 2b). The results demonstrate PDMS-PGMA copolymer was successfully synthesized by ATRP. Meanwhile, the deconvoluted C1s XPS spectrum of the composite paper (GO-3) in Figure 2b also has the signal of C-Si, indicating that PDMS-PGMA was introduced into the GO interlayer. And the low intensity of C-Si signal shows that PDMS accounts for a small proportion in block copolymer (10%), which is consistent with FTIR results. Furthermore, the peaks of C-OH, C-O-C, C=O, and O-C=O groups in the GO-3 shift from 285.5 (GO), 287.1(GO)/286.7(PDMS-PGMA), 287.8/287.6, 288.7/289.0 eV to 285.7, 286.8, 287.7 and 289.1 eV, respectively, demonstrating the existence of non-covalent interaction (H-bonding) between GO sheets and the PDMSPGMA copolymer.22 The results provide additional evidence for the interaction between GO and PDMS-PGMA. In order to further understand the interaction between GO sheets and PDMS-PGMA, the rheological behavior of PDMS-PGMA and composites (GO-50) solutions is shown in Figure 3(a). The storage modulus G′ and loss modulus G″ of the composite (GO-50) solution are higher than that of PDMS-PGMA solution and GO solution. The result may be attributed to the strong interactions between PDMS-PGMA and GO, also helpful for improving the mechanical properties of the composite papers.25-26 Furthermore, to exclude the interference of the concentration of PDMS-PGMA in solution, it can be seen that G′ and G″ of PDMS-PGMA solution have a little dependence on the PDMS-PGMA concentration (Figure S4). It can be deduced that the strong interactions did exist between GO sheets and PDMS-PGMA. It is expected that the GO paper show a highly ordered layered structure, the GO/PDMS-PGMA composite papers exhibited similarly high degree of order structure (Figure 1b). The structural changes of composite papers were confirmed by XRD, as show in Figure 3(b). While the GO paper exhibited a sharp peak at 2θ=10°, indicating that the GO paper has a highly ordered layered structure. For the composite papers, 2θ of GO sheets clearly decreased from ca. 9.3° for 7.5 wt% GO content to ca. 8.4° for 50 wt% GO content, indicating the d-spacing of the GO sheets increased from


Page 10 of 24

Page 11 of 24

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


9.5 Å to 10.5 Å with increasing GO content (Figure 3(c)). The result shows that the PDMS-PGMA copolymer successfully intercalated into the GO sheets. Compared with the initial GO d-spacing of 8.8 Å, the GO d-spacing of the composite papers increased by 0.7 to 1.7 Å, which was smaller than 2.82 Å (the van der Waals diameter of water).27 This phenomenon might be attributed to that the PDMS-PGMA copolymer in the interlamination of GO formed a crosslinking structure with GO sheets via H-bonding and rearranged for the lowest energy state, which is conducive to enhancing the mechanical properties of the composites.28 As shown in Figure 4 and Figure S5, the PDMS-PGMA copolymer macromolecules exhibit good dispersion on the GO surface. When the PDMS-PGMA content increased from 7.5% to 50%, the amount of the PDMS-PGMA macromolecules absorbed on GO surface increased as shown in Figure 4 and Figure S5. Furthermore, the amount of the PDMS-PGMA macromolecules mostly absorbed on GO surface, indicating that GO had stronger coordination or cooperation with PDMS-PGMA than mica

during

the

solvent

evaporation

process.

Therefore

the

strong

coordination/cooperation between GO and PDMS-PGMA is considered as a driving force to form “phase interface”, and beneficial for the load transfer between PDMSPGMA and GO sheets.

Figure 4. AFM images of GO and GO/PDMS-PGMA with different PDMS-PGMA contents: (a) GO, (b) GO-30 (30 wt%), (c) GO-50 (50 wt%).



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Figure 5. (a) Tensile stress-strain curves of GO paper, PDMS-PGMA paper and GO/PDMSPGMA papers. (b) Digital image indicating the ability of GO/PDMS-PGMA （GO-20） film


Page 12 of 24

Page 13 of 24

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(thickness: ~10 μm, width: ~4 mm) to completely support ~200 g of mass, which equates to 49 MPa of stress. (c) The ultimate strength and (d) toughness of GO/PDMS-PGMA composites with different PDMS-PGMA contents (wt %).

3.2. Mechanical Properties of GO and GO/PDMS-PGMA composite papers The analysis results of FTIR, XPS, XRD and AFM demonstrated that the strong interactions existed between GO sheets and PDMS-PGMA, and the interactions would contribute to improved mechanical properties of GO papers. The tensile stressstrain curves were obtained on GO and its composite papers with varying PDMSPGMA content from 0 to 50 wt% in Figure 5. Obviously, the presence of PDMSPGMA improved the mechanical properties of the GO papers. Compared with pure GO paper, the tensile strength of composites was significantly enhanced. GO-7.5 has the tensile strength of 216 MPa, 137% higher than that of GO. Surprisingly, GO-15 had the maximum tensile strength of 309 MPa, 240% higher than GO (Figure 5(c)). Compared with the reported composite papers treated by H-bonding interaction such as PVA and PMMA, as we know, the composite paper of GO-15 reported in our work exhibit extraordinary high tensile strength. Its tensile stress was 3.85 times higher than that of PVA-GO film (80.2 MPa), and 2.09 times higher than that of PMMA-GO film (148.3 MPa).13 However, further increasing PDMS-PGMA content resulted in the decrease of tensile strength of the GO/PDMS-PGMA composite papers. This may be attributed to that more and more PDMS-PGMA macromolecules appeared in the composite papers, and PDMS-PGMA had the tensile stresses around 22 MPa at the extension range from 3% to 5%. Very high PDMS-PGMA content in the composite papers negatively affected their tensile strength. In addition, higher PDMS-PGMA content negatively affected the uniform dispersion of PDMS-PGMA, which may result in the decrease of the mechanical properties of the composite papers. Despite this, the GO/PDMS-PGMA composite papers remained high mechanical strength. The hanging weights test intuitively showed its load bearing capacity for the composite papers (Figure 5(b)). The GO-20 (thickness: ~10 μm, width: ~4 mm) paper had a high tensile strength, and could completely support ~ 200 g of mass, which equated to a 49MPa full force. As for the other materials and methods for fabricating GO-based nacre, it could not comprehensively enhance the mechanical properties. For example, the PGO-PEI composites were constructed using polyetherimide (PEI) as adhesive to crosslinking GO sheets, achieving high tensile strength (209 MPa).29 However, the elongation and toughness dramatically decreased into only 0.22 % and 0.23 MJ·m-3, respectively. GO



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

composite papers were obtained by using a linear molecule, glutaraldehyde (GA), as adhesive to covalently crosslink.9 The tensile strength of the GO papers got 101 MPa, while the toughness of the GO paper was only ~0.3 MJ·m-3, which was attributed to the short GA chains. However, GO/PDMS-PGMA composite papers exhibited a good combination of high tensile strength and toughness compared with most other binary GO-based composites with different interface interactions, such as ionic bonding (GO-Ca2+, GO-Mg2+), hydrogen bonding (GO-PVA, GO-PMMA) and covalent bonding (GO-PAA, GO-GA, GO-PCDO, GO-PEI, GO-PDA), as shown in Figure 6. For example, compared with GO paper, the elongation at break of composite paper (GO-7.5) was ~3.3%, corresponding to the toughness of ~4.6 MJ·m-3. Furthermore the composite paper (GO-15) achieved the maximum toughness of 6.6 MJ·m-3, increasing by 719% (Figure 5(d)). Further increasing the PDMS-PGMA content, the toughness of composite papers began decreasing but stayed relatively high value. The results indicate that the introduction of PDMS-PGMA resulted in obtaining the flexibility of GO papers. Obviously, the excellent mechanical properties of composite papers were attributed to the strongly interaction between GO sheets and PDMSPGMA.

Figure 6. Comparison of tensile strength and toughness of our composite paper (GO-15) with other GO-based composites with different interface interactions, such as ionic interaction (green squares) of GO-Ca2+, GO-Mg2+, π-π conjugated interaction (pink quadrangle) of RGO-PAPB, hydrogen bonding (gray triangles) of GO-PVA, GO-PMMA and covalent cross-linking (red cycles) of GO-PAA, GO-GA, GO-PCDO, GO-PEI, GO-PDA. PAA: Polyallylamine, GA: Glutaraldehyde, PCDO: 10, 12-pentacosadiyn-1-ol, PDA: polydopamine; PAPB: poly(acrylic acid-co-(4-acrylamidophenyl) boronic acid).


Page 14 of 24

Page 15 of 24

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


For GO-based nanocomposites, most of the current researches focus on improving the mechanical properties and there is still room for improvement. In order to obtain high mechanical properties, it requires new methods and “new adhesive”. Recently, new strategies are applied to the preparation of GO nanocomposites. Xiong et al. fabricated GO nanocomposites via nonconventional spin-assisted layer-by-layer assembly (SA-LbL) method, using organic solvent and cellulose nanocrystals (CNC) as cross-linking agent.34-35 The GO nanocomposites show higher mechanical properties than other GO-based layered materials.

Figure 7. SEM images of the fracture surfaces of the composite papers with different PDMSPGMA contents: (a) 0 wt% (GO), (b) 7.5 wt% (GO-7.5), (c) 15 wt% (GO-15), (d) 20 wt% (GO20), (e) 30 wt% (GO-30) and (f) 50 wt% (GO-50).

Figure 8. (a) SEM mapping photograph of fracture surfaces of the composite paper (GO-20), and



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

elemental mapping images of GO-20: carbon mapping (b), oxygen mapping (c) and silicon mapping (d). The results showed that PDMS-PGMA existed in the interlayer of GO which played the role of “cross-linking agent” and uniformly dispersed in the interlayer of GO.

The cross-sectional morphology of the composite papers was observed by SEM as shown in Figure 7. All the GO and composite papers maintained highly ordered lamellar structure, and the interlayer distance significantly increased with increasing PDMS-PGMA content, which was consistent with the results from XRD. Due to the crosslinking of PDMS-PGMA, the composite papers with highly ordered lamellar structure exhibited high mechanical strength. In order to further investigate the distribution of PDMS-PGMA in composite papers, the morphology of the fractured surfaces was observed SEM (Figure S6) and a mapping technique (Figure 8). They clearly demonstrate that PDMS-PGMA existed in the interlayer of GO, which played the role of “cross-linking agent” and uniformly dispersed in the interlayer of GO. The results also provided another evidence of introduction of PDMS-PGMA into interlayer of GO. 3.3. Dielectric Properties of GO and GO/PDMS-PGMA composite papers The dielectric properties of PDMS-PGMA and GO/PDMS-PGMA composite papers were investigated as a function of frequency and PDMS-PGMA. Figure 9a showed the frequency dependent dielectric properties of the PDMS-PGMA and GO/PDMSPGMA composites at room temperature. In comparison with the PDMS-PGMA paper, the dielectric constant of the GO/PDMS-PGMA composite papers showed the dependence on PDMS content. At a low frequency range (101-103 Hz), the dielectric constant of the composite papers increased dramatically with increasing GO content, and up to 150 at 10 Hz at the GO content of 92.5 wt%. It was notable that the dielectric constant of the composite papers exhibited the strong frequency dependence at a wide range frequency (10-106 Hz). This phenomenon is a typical character for the percolative composites using graphene or GO nanosheets as filler, which has also been reported in previous researches.36-37 The interfacial polarization in composites as well as the mini-capacitor principle owing to the special structure can result in the increase of dielectric constant. Firstly, increased GO content the H-bonding between GO sheets and PDMS-PGMA could lead to the increase in the interface area, providing numerous sites for the reinforced MWS effect.38-39 Then the mini-capacitor principle lead to such increment.40 Due to the special layer structure of the composites, the GO and a very thin PDMS-PGMA layer served as electrodes and


Page 16 of 24

Page 17 of 24

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


dielectric construct many mini-capacitors in GO/PDMS-PGMA composite papers. The mini-capacitors in GO/PDMS-PGMA composites have an important role in the increase of dielectric constant.

Figure 9. (a) Dielectric constant and (b) dielectric loss tangent as a function of frequency for PDMS-PGMA and GO/PDMS-PGMA composites with different PDMS-PGMA content

A similar feature of the dielectric loss tangent (tan δ) of the composites increased with increasing GO contents (Figure 9b), which showed a dependence on the frequency. When the GO content was beyond 50wt%, the tan δ of the composites kept the value of 0.5 around 107 Hz, indicating promising composites with high dielectric constant and low dielectric loss. However, it should be noted that tan δ of composites with 50wt% and 30wt% of GO was slightly higher than that of the others at the frequency range of 105-107 Hz. This is reasonable because the highly ordered layered structure



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

of the composite was corrupted, resulting in some defects and voids in composite which can be seen from the SEM results (Figure 7). As for the composite papers, the dielectric loss could be suppressed due to H-bonding between GO sheets and PDMSPGMA, thus improving the interfacial adhesion resulting in suppressed the motion of molecular dipoles of PDMS-PGMA and the aggregation of charge in composites.41-42 4. Conclusions A triblock copolymer PDMS-PGMA containing the “soft segment” PDMS and “active segment” PGMA was successfully synthesized by ATRP. PDMS-PGMA was used as an active adhesive to produce of layered graphene oxide/polymer composite papers by using vacuum-assisted self-assembly method. Compared with other composites using the biomolecules and commercial polymers, the GO/PDMS-PGMA composites exhibited enhanced mechanical and electrical properties, such as higher tensile stress, toughness and dielectric constant. Furthermore, the GO/PDMS-PGMA composites exhibited better mechanical properties than most other GO based films reported so far using the physical crosslinking. Thus, the GO/PDMS-PGMA composites show wide potential applications such as electronic and engineering materials. Moreover, it is also expected that this work provide some guidance for the preparation of GO composite papers.

ASSOCIATED CONTENT Supporting Information Appendix S1, 3D AFM and Raman spectrum; Appendix S2, TGA; Appendix S3, XPS; Appendix S4, rheometry; Appendix S5, AFM; Appendix S6, SEM. This material is available free of charge via the Internet at http://pubs.acs.org. AUTHOR INFORMATION * E-mail: [email protected] Notes The authors declare no competing financial interest. ACKNOWLEDGMENTS The work is supported by a National Natural Science Foundation of China (No. 51273109, 51235008).


Page 18 of 24

Page 19 of 24

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


REFERENCES 1.

Lee, S. H.; Kim, H. W.; Hwang, J. O.; Lee, W. J.; Kwon, J.; Bielawski, C. W.; Ruoff, R. S.; Kim, S. O. Three-Dimensional Self-Assembly of Graphene Oxide Platelets into Mechanically Flexible Macroporous Carbon Films. Angew. Chem. 2010, 122, 10282-10286.

2.

Huang, L.; Li, C.; Yuan, W. J.; Shi, G. Q. Strong Composite Films with Layered Structures Prepared by Casting Silk Fibroin-Graphene Oxide Hydrogels. Nanoscale 2013, 5, 3780-3786.

3.

Xu, J.; Wang, K.; Zu, S. Z.; Han, B. H.; Wei, Z. X. Hierarchical Nanocomposites of Polyaniline Nanowire Arrays on Graphene Oxide Sheets with Synergistic Effect for Energy Storage. ACS Nano 2010, 4, 5019-5026.

4.

Weaver, C. L.; LaRosa, J. M.; Luo, X.; Cui, X. T. Electrically Controlled Drug Delivery from Graphene Oxide Nanocomposite Films. ACS Nano 2014, 8, 1834-1843.

5.

Cheng, Q.; Wu, M.; Li, M.; Jiang, L.; Tang, Z. Ultratough Artificial Nacre Based on Conjugated Cross-Linked Graphene Oxide. Angew. Chem. 2013, 125, 3838-3843.

6.

Sumboja, A.; Foo, C. Y.; Wang, X.; Lee, P. S. Large Areal Mass, Flexible and Free-Standing Reduced Graphene Oxide/Manganese Dioxide Paper for Asymmetric Supercapacitor Device. Adv. Mater. 2013, 25, 2809-2815.

7.

Cheng, Q.; Jiang, L.; Tang, Z. Bioinspired Layered Materials with Superior Mechanical Performance. Acc. Chem. Res. 2014, 47, 1256-1266.

8.

Park, S.; Lee, K. S.; Bozoklu, G.; Cai, W.; Nguyen, S. T.; Ruoff, R. S. Graphene Oxide Papers Modified by Divalent Ion-Enhancing Mechanical Properties via Chemical Cross-Linking. ACS Nano 2008, 2, 572-578.

9.

Gao, Y.; Liu, L. Q.; Zu, S. Z.; Peng, K.; Zhou, D.; Han, B. H.; Zhang, Z. The Effect of Interlayer Adhesion on the Mechanical Behaviors of Macroscopic Graphene Oxide Papers. ACS Nano 2011, 5, 2134-2141.

10.

Cheng, Q.; Wu, M.; Li, M.; Jiang, L.; Tan, Z. Ultratough Artificial Nacre Based on Conjugated Cross-linked Graphene Oxide. Angew. Chem., Int. Ed. 2013, 52, 3750-3755.



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

11.

Page 20 of 24

Park, S.; Dikin, D. A.; Nguyen, S. T.; Ruoff, R. S. Graphene Oxide Sheets Chemically Cross-Linked by Polyallylamine. J. Phys. Chem. C. 2009, 113, 15801-15804.

12.

Dikin, D. A.; Stankovich, S.; Zimney, E. J.; Piner, R. D.; Dommett, G. H. B.; Evmenenko, G.; Nguyen, S. T.; Ruoff, R. S. Preparation and Characterization of Graphene Oxide Paper. Nature 2007, 448, 457-460.

13.

Putz, K. W.; Compton, O. C.; Palmeri, M. J.; Nguyen, S. T.; Brinson, L. C. High-Nanofiller-Content Graphene Oxide-Polymer Nanocomposites via Vacuum-Assisted Self-Assembly. Adv. Funct. Mater. 2010, 20, 3322-3329.

14.

Wan, S.; Peng, J.; Li, Y.; Hu, H.; Jiang, L.; Cheng, Q. Use of Synergistic Interactions to Fabricate Strong, Tough, and Conductive Artificial Nacre Based on Graphene Oxide and Chitosan. ACS Nano 2015, 9, 9830-9836.

15.

Shi, L. Y.; Shen, Z.; Fan, X. H. Order-Order Transition in a Rod-Coil Diblock Copolymer Induced by Supercritical CO2. Macromolecules 2011, 44, 29002907.

16.

Muppalla, R.; Jewrajka, S. K. Synthesis, Morphology and Properties of Poly (dimethylsiloxane)/Poly

(n-butyl

acrylate)

Mixed

Soft

Block-Based

Copolymers: A New Class of Thermoplastic Elastomer. Polymer 2012, 53, 1453-1464. 17.

Bai, X.; Wan, C.; Zhang, Y; Zhai, Y. H. Reinforcement of Hydrogenated Carboxylated Nitrile-Butadiene Rubber with Exfoliated Graphene Oxide. Carbon 2011, 49, 1608-1613.

18.

Cai, W. W.; Piner, R. D.; Stadermann, F. J.; Park, S.; Shaibat, M. A.; Ishii, Y.; An, J. Synthesis and Solid-State NMR Structural Characterization of

13

C-

Labeled Graphite Oxide. Science 2008, 321, 1815-1817. 19.

Lerf, A.; He, H.; Forster, M.; Klinowski, J. Structure of Graphite Oxide Revisited. J. Phys. Chem. B. 1998, 102, 4477-4482.

20.

Çelik, S. Ü.; Bozkurt, A. Preparation and Proton Conductivity of Acid-Doped 5-aminotetrazole Functional Poly (glycidyl methacrylate). Eur. Polym. J. 2008, 44, 213-218.

21.

Zhu, W. K.; Cong, H. P.; Yao, H. B.; Mao, L. B.; Asiri, A. M.; Alamry, K. A.;


Page 21 of 24

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Yu, S. H. Bioinspired, Ultrastrong, Highly Biocompatible, and Bioactive Natural Polymer/Graphene Oxide Nanocomposite Films. Small 2015, 11, 4298-4302. 22.

Chen, K.; Shi, B.; Yue, Y.; Qi, J.; Guo, L. Binary Synergy Strengthening and Toughening of Bio-Inspired Nacre-Like Graphene Oxide/Sodium Alginate Composite Paper. ACS Nano 2015, 9, 8165-8175.

23.

Chen, Y.; Zhang, X.; Yu, P.; Ma, Y. Stable Dispersions of Graphene and Highly Conducting Graphene Films: A New Approach to Creating Colloids of Graphene Monolayers. Chem. Commun. 2009, 30, 4527-4529.

24.

Mei, X.; Ouyang, J. Ultrasonication-Assisted Ultrafast Reduction of Graphene Oxide by Zinc Powder at Room Temperature. Carbon 2011, 49, 5389-5397.

25.

Vallés, C.; Young, R. J.; Lomax, D. J.; Kinloch, I. A. The Rheological Behaviour of Concentrated Dispersions of Graphene Oxide. J. Mater. Sci. 2014, 49, 6311-6320.

26.

Manivel, P.; Kanagaraj, S; Balamurugan, A.; Ponpandian, N.; Mangalaraj, D.; Viswanathan, C. Rheological Behavior-Electrical and Thermal Properties of Polypyrrole/Graphene Oxide Nanocomposites. J. Appl. Polym. Sci. 2014, 131(16).

27.

Zhu, J.; Zhang, H.; Kotov, N. A. Thermodynamic and Structural Insights into Nanocomposites Engineering by Comparing Two Materials Assembly Techniques for Graphene. ACS Nano 2013, 7, 4818-4829.

28.

Compton, O. C.; Cranford, S. W.; Cranford, S. W.; Putz, K. W.; An, Z.; Brinson, L. C.; Buehler, M. J.; Nguyen, S. T. Tuning The Mechanical Properties of Graphene Oxide Paper and

Its Associated Polymer

Nanocomposites by Controlling Cooperative Intersheet Hydrogen Bonding. ACS Nano 2012, 6, 2008-2019. 29.

Tian, Y.; Cao, Y.; Wang, Y.; Yang, W.; Feng, J. Realizing Ultrahigh Modulus and High Strength of Macroscopic Graphene Oxide Papers Through Crosslinking of Mussel-Inspired Polymers. Adv. Mater. 2013, 25, 2980-2983.

30.

Li, Y. Q.; Yu, T.; Yang, T. Y.; Zheng, L. X.; Liao, K. Bio-Inspired Nacre-Like Composite Films Based on Graphene with Superior Mechanical, Electrical, and Biocompatible Properties. Adv. Mater. 2012, 24, 3426-3431.



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

31.

An, Z.; Compton, O. C.; Putz, K. W.; Brinson, L. C.; Nguyen, S. T. BioInspired Borate Cross-Linking in Ultra-Stiff Graphene Oxide Thin Films. Adv. Mater. 2011, 23, 3842-3846.

32.

Cui, W.; Li, M.; Liu, J.; Wang, B.; Zhang, C.; Jiang, L.; Cheng, Q. A Strong Integrated Strength and Toughness Artificial Nacre Based on Dopamine CrossLinked Graphene Oxide. ACS Nano 2014, 8, 9511-9517.

33.

Zhang, M.; Huang, L.; Chen, J.; Li, C.; Shi, G. Ultratough, Ultrastrong, and Highly Conductive Graphene Films with Arbitrary Sizes. Adv. Mater. 2014, 26, 7588-7592.

34.

Xiong, R.; Hu, K.; Grant, A. M.; Ma, R.; Xu, W.; Lu, C. H.; Zhang, X. X.; Tsukruk, V. V. Ultrarobust Transparent Cellulose Nanocrystal-Graphene Membranes with High Electrical Conductivity. Adv. Mater. 2016, 28, 15011509.

35.

Xiong, R.; Hu, K.; Zhang, S.-D.; Lu, C. H.; Tsukruk, V. V. Ultrastrong Freestanding Graphene Oxide Nanomembranes with Surface-Enhanced Raman Scattering Functionality by Solvent-Assisted Single-Component Layer-By-Layer Assembly. ACS Nano 2016, 10, 6702-6715.

36.

Wang, L.; Dang, Z. M. Carbon Nanotube Composites with High Dielectric Constant at Low Percolation Threshold. Appl. Phys. Lett. 2005, 87, 042903.

37.

Liu, H.; Shen, Y.; Song, Y.; Nan, C. W.; Lin, Y.; Yang, X. Carbon Nanotube Array/Polymer Core/Shell Structured Composites with High Dielectric Permittivity, Low Dielectric Loss, and Large Energy Density. Adv. Mater. 2011, 23, 5104-5108.

38.

Kumar, S. K.; Castro, M.; Saiter, A.; Delbreilh, L.; Feller, J. F.; Thomas, S.; Grohens,

Y.

Development of

Poly (isobutylene-co-isoprene)/Reduced

Graphene Oxide Nanocomposites for Barrier, Dielectric and Sensing Applications. Mater. Lett. 2013, 96, 109-112. 39.

Dang, Z.-M.; Wang, L.; Yin, Y. I; Zhang, Q.; Lei, Q. Q. Giant Dielectric Permittivities

in

Functionalized

Carbon-Nanotube/Electroactive-Polymer

Nanocomposites. Adv. Mater. 2007, 19, 852-857. 40.

Min, C.; Yu, D.; Cao, J. A Graphite Nanoplatelet/Epoxy Composite with High Dielectric Constant and High Thermal Conductivity. Carbon 2013, 55, 116-


Page 22 of 24

Page 23 of 24

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


125. 41.

Roy, M.; Nelson, J. K.; MacCrone, R. K.; Schadler, L. S.; Reed, C. W.; Keefe, R. Polymer Nanocomposite Dielectrics-The Role of The Interface. IEEE Trans. Dielectr. Electr. Insul. 2005, 12, 629-643.

42.

Yang, K.; Huang, X.; Huang, Y.; Xie, L; Jiang, P. Fluoro-Polymer@ BaTiO3 Hybrid

Nanoparticles

Prepared

via

RAFT

Polymerization:

Toward

Ferroelectric Polymer Nanocomposites with High Dielectric Constant and Low Dielectric Loss for Energy Storage Application. Chem. Mater. 2013, 25, 2327-2338.



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Table of Contents (TOC) Graphic


Page 24 of 24

Polymer Nanocomposite Paper with High

Recommend Documents