Ultralight Microcellular PolymerâGraphene Nanoplatelet Foams with

Subscriber access provided by UCL Library Services

Applications of Polymer, Composite, and Coating Materials

Ultralight Microcellular Polymer-Graphene Nanoplatelet Foams with Enhanced Dielectric Performance Mahdi Hamidinejad, Biao Zhao, Raymond K.M. Chu, Nima Moghimian, Hani E. Naguib, Tobin Filleter, and Chul B Park ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b03777 • Publication Date (Web): 10 May 2018 Downloaded from http://pubs.acs.org on May 13, 2018

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 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 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.

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 32 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

Ultralight Microcellular Polymer-Graphene Nanoplatelet Foams with Enhanced Dielectric Performance Mahdi Hamidinejad a, b, ⊥, Biao Zhao a, ⊥, Raymond K.M. Chu a, Nima Moghimian c, Hani Naguib d , Tobin Filleter b*, and Chul B. Park a* a

Microcellular Plastics Manufacturing Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, 5 King’s College Road, Toronto, Canada M5S 3G8

b

Nano Mechanics and Materials Lab, Department of Mechanical and Industrial Engineering, University of Toronto, 5 King’s College Road, Toronto M5S 3G8, Canada c

d

NanoXplore Inc., 25 Boul. Montpellier, Saint-Laurent, QC, H4N 2G3

Department of Mechanical and Industrial Engineering, University of Toronto, 5 King’s College Road, Toronto M5S 3G8, Canada ⊥

*

M.H. and B.Z. equally contributed Corresponding Authors’ Information: E-mail: [email protected]; [email protected]

Abstract Dielectric polymer nanocomposites with high dielectric constant (ε'), and low dielectric loss (tan δ) are extremely desirable in the electronics industry. Percolative polymer-graphene nanoplatelet (GnP) composites have shown great promise as dielectric materials for high-performance capacitors. Herein an industrially-viable technique for manufacturing a new class of ultralight polymer composite foams using commercial GnPs with excellent dielectric performance is presented. Using this method, the high-density polyethylene (HDPE)-GnPs composites with a microcellular structure were fabricated by melt mixing. This was followed by supercritical fluid (SCF) treatment and physical foaming in an extrusion process, which added an extra layer of design flexibility. The SCF treatment effectively in-situ exfoliated the GnPs in the polymer matrix. Moreover, the generation of a microcellular structure produced numerous parallel-plate nanocapacitors consisting of GnP pairs as electrodes with insulating polymer as nanodielectrics. This significantly increased the real permittivity and decreased the dielectric loss. The ultralight extruded HDPE-1.08 vol.% GnP composite foams, with a 0.15 g.cm-3 density, had an excellent 1 ACS Paragon Plus Environment

ACS Applied Materials & Interfaces 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

combination of dielectric properties (ε'=77.5, tan δ=0.003 at 1×105 Hz) which were superior to their compression-molded counterparts (ε'=19.9, tan δ =0.15 and density of =1.2 g.cm-3) and to those reported in the literature. This dramatic improvement resulted from in-situ GnP’s exfoliation and dispersion, as well as a unique GnP parallel-plates arrangement around the cells. Thus, this facile method provides a scalable method to produce ultralight dielectric polymer nanocomposites, with a microscopically-tailored microstructure for use in electronic devices. Keywords: Dielectric permittivity; dielectric loss; graphene nanoplatelets; polymer nanocomposites; physical foaming; microcellular structure

1.

Introduction

High performance dielectric materials are vital to the development of next-generation miniaturized electronic devices. Dielectric materials with high dielectric permittivity (ε') and low dielectric loss (tan δ) have been receiving increasing interest in modern electronics as the capacitors and integrated capacitors

1–4

. Multifunctional, lightweight, and low-cost polymer

nanocomposites show much promise for use as dielectric materials. Their dielectric permittivity and dielectric loss tunability is large; their resistance to chemicals is outstanding; they are easily processed, and they have tailorable thermal and mechanical properties 5,6. Polymers have an extremely low dielectric loss and a high dielectric breakdown strength; however, they suffer from a low dielectric constant (ε'103 Hz). The lower dielectric loss at higher frequencies was proportional to the polarization loss 67,69, This was further restricted after foaming was introduced. Thus, the dielectric loss dropped down to 0.003 at 1×105 Hz in the extruded foam samples. However, the dielectric loss of their SCM counterpart samples was 0.18 at 1×105 Hz, and it sharply increased as the frequency decreased. The reduction in the polarization loss in the extruded foam samples was attributed to a better dispersion of the GnPs and to their better interfacial interaction with the polymer matrix. This was due to the dissolution of the scCO2 in the polymer. Thus insulating layers formed among the GnPs to prevent the migration of

(a)

Broadband dielectric loss (tan δ)

the space charge within the nanocomposites 66.

Broadband real permittivity (ε')

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


Foam

80 60 So l id

40 20 Neat HDPE

0 101

102

103

104

105

102

(b)

101

Sol id

100 10-1

Foam

10-2 10-3 10

Neat HDPE

-4

101

Frequency (Hz)

102

103

104

105

Frequency (Hz)

Figure 7. (a) Broadband dielectric permittivity; (b) Broadband dielectric loss of the SCM HDPE9.8 vol.% GnP composites and their extruded foam (with a density of 0.15 g.cm-3 or ~8 times foam expansion ratio) counterparts.

21 ACS Paragon Plus Environment


3.4.1. Effect of the density on the dielectric properties Figure 8 shows the variation of the real permittivity and the dielectric loss as a function of the density of the extruded foam samples, which were made from solid precursors containing 4.5 vol.% GnP. When the density of the HDPE-GnP composites decreased from 1.07 to 0.08 g.cm-3, the ε' increased from 9.6 to 22.3, and the tan δ decreased from 0.04 to 0.006. A further decrease in the density to 0.05 g.cm-3, however, slightly decreased the ε' to 18.8. Meanwhile, the dielectric loss continued to decrease to as low as 0.004. The optimal behavior of the ε' can be mainly attributed to the changes in the microcellular structures, when their densities (that is, the foam expansion ratios) were varied as was discussed in Section 3.1.

20

100

10-1

15 10-2

10 5

Dielectric loss (tan δ)

Real permittivity Dielectric loss

25

Real permittivity (ε')

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

Page 22 of 32

10-3 0.1

-3

1

Density (g.cm ) Figure 8. Variations in real permittivity and dielectric loss measured at 1×10+3 Hz as a function of density in the extruded HDPE-GnP composite foams made from solid precursors containing 4.5 vol% GnP. The parallel-plates arrangement of the GnPs within the cell walls enhanced the effective interfaces between the adjacent GnPs (Figure 9a), and thus increased the real permittivity. As the density continued to decrease, the cell walls were compressed in the thickness direction due to bubble growth (Figure 9b), which can decrease the interspace distances between the adjacent 22 ACS Paragon Plus Environment

Page 23 of 32 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


GnPs. This further enhanced the ε'. However, when the density was decreased to 0.05, the cell wall thickness dropped to approximately 1 µm, and the number of adjacent GnPs in the cell walls decreased dramatically, due to polymer matrix’s excessive compression. Interestingly, almost no GnP can be found in the cell wall for the lower density foams (Figure 9c). This resulted in lower effective interfaces between the adjacent GnPs and in lower real permittivity. During the fast cellular growth process, the solid fillers (e.g. GnPs) could barely flow together with the polymer melt

32

. Therefore, the number of GnPs in a unit area of the cell walls decreased with the

reduction in the density of foam-extruded samples. The decrease in the tan δ when the density dropped can mainly be attributed to the higher foam expansion (up to 21-fold), which further separated the GnPs and, thereby, resulted in a loss of conductive networks. This, in turn, led to a lower Ohmic loss. Figure 9d shows the ideal 2-D conceptualization of the change in the GnP’s alignment with the density. Interestingly, the tailored microcellular structure further enhanced the HDPE-GnP composites’ dielectric performance. The facile sc-CO2-treatment and physical foaming of the HDPE-GnP composites significantly increased their real permittivity (ε') and greatly decreased both their dielectric loss (tan δ) and their density. As a result, an excellent combination of the dielectric properties, together with an ultra-low density, resulted. In the extruded 1.08 vol.% HDPE-GnP composite foam with a density of 0.15 g.cm-3, the tan δ dropped down as low as 0.003 at 1×105 Hz while the ε' reached 77.5. These results were greatly superior to those of the SCM nanocomposites (ε'~19.9, tan δ ~0.15 and density of ~1.2 g.cm-3).



Page 24 of 32

Figure 9. SEM and TEM micrographs of the extruded HDPE-GnP composite foams made from solid precursors containing 4.5 vol% GnP, which show the GnPs’ arrangement at different densities including: (a) 0.13 g.cm-3; (b) 0.08 g.cm-3; and (c) 0.05 g.cm-3. (d) Ideal 2-D conceptualization of GnP’s arrangement in cell walls as the density decreased. Table 1 shows some of the recent advances made in the development of polymer nanocomposites as dielectric materials. And they are compared with the dielectric performance of the HDPE-GnP reported in our study. Most of the presented batch-type studies

3,4,11,16,17,24,25,29,26–28

have

undertaken complex synthesis procedures which are challenging to be scaled up and/or have high material cost. For instance, Wen et al. achieved a very good combination of the real permittivity 24 ACS Paragon Plus Environment

Page 25 of 32 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


(ε'=74) and the dielectric loss (tan δ =0.08)

16

, however, their fabrication method was a tedious

multiple-step synthesis process (three-step process for GnP preparation + synthesis of poly(vinylidene fluoride-trifluorethylene) copolymer with internal double-bonds through a dehydrochlorination process). Jin et al. also reported another great combination of dielectric properties (ε'=71.7, and tan δ =0.045) 11 for the poly (vinylidene fluoride) hybrid nanocomposites (containing MWNT/BaTiO3) which were fabricated through a complex miscible-immiscible coagulation method. However, the required nanomaterials loading was rather high which resulted in heavy (density of ~4.6 g.cm-3) and expensive dielectric materials. Table 1. Dielectric performance and density of different polymer nanocomposites Filler content 4.0 vol%

Frequency (Hz) 103

Dielectric permittivity 74

Dielectri c loss 0.08

Fabrication method solution casting, functionalization and crosslinking

Density (g.cm-3) ~1.8

poly (vinylidene fluoride)/ BaTiO3 /BaTiO3 nanofibers

30 vol%/3 vol%

102

27

0.06

emulsion polymerization

~1.1

28

poly (vinylidene fluoride-cohexafluoroprop ylene)/titanium dioxidemodified reduced graphene oxide (rGO)

20 wt.%

102

24.5

0.22

in-situ assembling TiO2 on graphene oxide (GO)+ solution mixing and drop casting

~1.86

4

poly(pphenylene benzobisoxazol e)/ Functionalized Graphene Nanosheets

2.0 wt.%

103

66.27

0.045

polymer chains grafting in GnPs, in-situ polymerization followed by further thermal treatment

~1.57

29

Materials poly(vinylidene fluoridetrifluorethylene )/graphene nanosheets


Ref. 16


Page 26 of 32

poly (vinylidene fluoride)/functi onalized graphene– BaTiO3

1.25/30 vol.%

106

65

0.35

GO synthesis followed by twostep solution mixing and hotpressing

~3

3

polydimethylsil oxane/thermall y expanded graphene nanoplates

2.0 wt%

103

89

1.5

thermal exfoliation of graphene followed by solution mixing and vulcanization

~0.97

17

polyimide /graphene/BaTi O3

1.0/16vol.%

102

31

0.03

Multiple step solution mixing

~3.5

26

cyanoethyl pullulan polymer/carbon nanotubes/rGO

0.062 wt.%

102

32

0.051

carbon nanotubes/rGO fabricated by thermal CVD followed by solution mixing

~1.1

24

poly (vinylidene fluoride) / multiwall carbon nanotubes /BaTiO3 diglycidyl ether of bisphenolA/rGO

3.0/37.1vol. %

103

71.7

0.045

miscibleimmiscible coagulation method followed by hot pressing

~4.6

11

1.0 wt.

103

32

0.08

covalent functionalization and solution mixing and curing

~1.7

27

HDPE/GnP

1.08 vol%*

103

77.5

0.014

melt mixing and foam extrusion

0.15

this work

HDPE/GnP

1.08 vol%*

105

77.1

0.003


0.15

this work

HDPE/GnP

0.8 vol.%*

103

39.7

0.012


0.14

this work

HDPE/GnP

0.5 vol.%*

103

18

0.010


0.13

this work

HDPE/GnP

0.5 vol.%*

103

22.3

0.006


0.08

this work

* the GnP vol.% is reported with respect to the total volume

4.

Conclusion

In this study, a new class of ultralight, microcellular dielectric HDPE-GnP composites was introduced. The composite foams of HDPE with highly exfoliated GnPs were developed using a melt mixing method, followed by a sc-CO2-treatment and physical foaming via an extrusion 26 ACS Paragon Plus Environment

Page 27 of 32 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


process. The generation of a microcellular structure provided a unique parallel-plate arrangement of GnPs around the cell walls. This significantly enhanced the real permittivity and greatly decreased the dielectric loss of the HDPE-GnP composites. For example, ultralight extruded HDPE-1.08 vol.% GnP foam with a density of 0.15 g.cm-3 had a high dielectric permittivity of ε'=77.5 and an extremely low dielectric loss of tan δ=0.003 at 1×105 Hz, which made it superior to solid compression-molded samples (ε'=19.9 and the tan δ=0.15 with a density of 1.2 g.cm-3). The extremely low dielectric loss, together with the enhanced real permittivity, of the extruded foam samples provided an excellent combination of dielectric properties. Our study showed that the tailored morphologies existing in the microcellular structure within the HDPE-GnP composites offer a novel, industrially viable and cost-effective method to develop ultralight dielectric materials with high permittivity and low dielectric loss. 5.

Acknowledgments:

The authors gratefully acknowledge NanoXplore Inc.’s financial support and donation of materials for this study. We also appreciate the Natural Sciences and Engineering Research Council of Canada’s (NSERC) financial support. M.H. would like to acknowledge funding from the NSERC Alexander Graham Bell Canada Graduate Scholarship program and the Ontario Graduate Scholarship.

References (1)

(2)

(3)

(4)

Dang, Z. M.; Yuan, J. K.; Zha, J. W.; Zhou, T.; Li, S. T.; Hu, G. H. Fundamentals, Processes and Applications of High-Permittivity Polymer-Matrix Composites. Prog. Mater. Sci. 2012, 57 (4), 660–723. Wu, C.; Huang, X.; Xie, L.; Wu, X.; Yu, J.; Jiang, P. Morphology-Controllable graphene–TiO2 Nanorod Hybrid Nanostructures for Polymer Composites with High Dielectric Performance. J. Mater. Chem. 2011, 21 (44), 17729–17736. Wang, D.; Zhou, T.; Zha, J.-W.; Zhao, J.; Shi, C.-Y.; Dang, Z.-M. Functionalized graphene– BaTiO3/ferroelectric Polymer Nanodielectric Composites with High Permittivity, Low Dielectric Loss, and Low Percolation Threshold. J. Mater. Chem. A 2013, 1 (20), 6162–6168. Tong, W.; Zhang, Y.; Yu, L.; Lv, F.; Liu, L.; Zhang, Q.; An, Q. Amorphous TiO2-Coated Reduced 27 ACS Paragon Plus Environment


(5)

Graphene Oxide Hybrid Nanostructures for Polymer Composites with Low Dielectric Loss. Chem. Phys. Lett. 2015, 638, 43–46. Prateek; Thakur, V. K.; Gupta, R. K. Recent Progress on Ferroelectric Polymer-Based Nanocomposites for High Energy Density Capacitors: Synthesis, Dielectric Properties, and Future Aspects. Chem. Rev. 2016, 116 (7), 4260–4317.

(6)

Yuan, J.; Yao, S.; Poulin, P. Dielectric Constant of Polymer Composites and the Routes to High-K or Low-K Nanocomposite Materials. In Polymer Nanocomposites: Electrical and Thermal Properties; Springer International Publishing: Cham, 2016; pp 3–28.

(7)

Ducharme, S. An inside-out Approach to Storing Electrostatic Energy. ACS Nano 2009, 3 (9), 2447–2450.

(8)

Padalia, D.; Bisht, G.; Johri, U. C.; Asokan, K. Fabrication and Characterization of Cerium Doped Barium titanate/PMMA Nanocomposites. Solid State Sci. 2013, 19, 122–129.

(9)

Nisa, V. S.; Rajesh, S.; Murali, K. P.; Priyadarsini, V.; Potty, S. N.; Ratheesh, R. Preparation, Characterization and Dielectric Properties of Temperature Stable SrTiO3/PEEK Composites for Microwave Substrate Applications. Compos. Sci. Technol. 2008, 68 (1), 106–112.

(10)

Hu, Y.; Zhang, Y.; Liu, H.; Zhou, D. Microwave Dielectric Properties of PTFE/CaTiO3 Polymer Ceramic Composites. Ceram. Int. 2011, 37 (5), 1609–1613.

(11)

Jin, Y.; Xia, N.; Gerhardt, R. A. Enhanced Dielectric Properties of Polymer Matrix Composites with BaTiO3 and MWCNT Hybrid Fillers Using Simple Phase Separation. Nano Energy 2016, 30, 407–416.

(12)

El Hasnaoui, M.; Triki, A.; Graça, M. P. F.; Achour, M. E.; Costa, L. C.; Arous, M. Electrical Conductivity Studies on Carbon Black Loaded Ethylene Butylacrylate Polymer Composites. J. Non. Cryst. Solids 2012, 358 (20), 2810–2815.

(13)

Ameli, A.; Wang, S.; Kazemi, Y.; Park, C. B.; Pötschke, P. A Facile Method to Increase the Charge Storage Capability of Polymer Nanocomposites. Nano Energy 2015, 15, 54–65.

(14)

Chang, J.; Liang, G.; Gu, A.; Cai, S.; Yuan, L. The Production of Carbon Nanotube/epoxy Composites with a Very High Dielectric Constant and Low Dielectric Loss by Microwave Curing. Carbon N. Y. 2012, 50 (2), 689–698. Müller, M. T.; Hilarius, K.; Liebscher, M.; Lellinger, D.; Alig, I.; Pötschke, P. Effect of Graphite Nanoplate Morphology on the Dispersion and Physical Properties of Polycarbonate Based Composites. Materials (Basel). 2017, 10 (5).

(15)

(16)

Wen, F.; Xu, Z.; Tan, S.; Xia, W.; Wei, X.; Zhang, Z. Chemical Bonding-Induced Low Dielectric Loss and Low Conductivity in High-K Poly(vinylidenefluoride-Trifluorethylene)/graphene Nanosheets Nanocomposites. ACS Appl. Mater. Interfaces 2013, 5 (19), 9411–9420.

(17)

Tian, M.; Wei, Z.; Zan, X.; Zhang, L.; Zhang, J.; Ma, Q.; Ning, N.; Nishi, T. Thermally Expanded Graphene Nanoplates/polydimethylsiloxane Composites with High Dielectric Constant, Low Dielectric Loss and Improved Actuated Strain. Compos. Sci. Technol. 2014, 99, 37–44.

(18)

Deng, H.; Lin, L.; Ji, M.; Zhang, S.; Yang, M.; Fu, Q. Progress on the Morphological Control of Conductive Network in Conductive Polymer Composites and the Use as Electroactive Multifunctional Materials. Prog. Polym. Sci. 2014, 39 (4), 627–655.

(19)

Dang, Z. M.; Zheng, M. S.; Zha, J. W. 1D/2D Carbon Nanomaterial-Polymer Dielectric Composites with High Permittivity for Power Energy Storage Applications. Small 2016, 12 (13), 1688–1701.

(20)

Dang, Z.-M.; Yuan, J.-K.; Yao, S.-H.; Liao, R.-J. Flexible Nanodielectric Materials with High Permittivity for Power Energy Storage. Adv. Mater. 2013, 25 (44), 6334–6365. Kim, H.; Abdala, A. A.; MacOsko, C. W. Graphene/polymer Nanocomposites. Macromolecules

(21)


Page 28 of 32

Page 29 of 32 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


2010, 43 (16), 6515–6530. (22)

Potts, J. R.; Dreyer, D. R.; Bielawski, C. W.; Ruoff, R. S. Graphene-Based Polymer Nanocomposites. Polymer (Guildf). 2011, 52 (1), 5–25.

(23)

Bianco, A.; Cheng, H. M.; Enoki, T.; Gogotsi, Y.; Hurt, R. H.; Koratkar, N.; Kyotani, T.; Monthioux, M.; Park, C. R.; Tascon, J. M. D.; et al. All in the Graphene Family - A Recommended Nomenclature for Two-Dimensional Carbon Materials. Carbon N. Y. 2013, 65, 1–6.

(24)

Kim, J. Y.; Kim, T.; Suk, J. W.; Chou, H.; Jang, J. H.; Lee, J. H.; Kholmanov, I. N.; Akinwande, D.; Ruoff, R. S. Enhanced Dielectric Performance in Polymer Composite Films with Carbon Nanotube-Reduced Graphene Oxide Hybrid Filler. Small 2014, 10 (16), 3405–3411.

(25)

Zhang, T.; Huang, W.; Zhang, N.; Huang, T.; Yang, J.; Wang, Y. Grafting of Polystyrene onto Reduced Graphene Oxide by Emulsion Polymerization for Dielectric Polymer Composites: High Dielectric Constant and Low Dielectric Loss Tuned by Varied Grafting Amount of Polystyrene. Eur. Polym. J. 2017, 94, 196–207.

(26)

Liu, J.; Tian, G.; Qi, S.; Wu, Z.; Wu, D. Enhanced Dielectric Permittivity of a Flexible Three-Phase Polyimide-Graphene-BaTiO3 Composite Material. Mater. Lett. 2014, 124, 117–119.

(27)

Wan, Y. J.; Yang, W. H.; Yu, S. H.; Sun, R.; Wong, C. P.; Liao, W. H. Covalent Polymer Functionalization of Graphene for Improved Dielectric Properties and Thermal Stability of Epoxy Composites. Compos. Sci. Technol. 2016, 122, 27–35.

(28)

Hu, P.; Shen, Y.; Guan, Y.; Zhang, X.; Lin, Y.; Zhang, Q.; Nan, C. W. Topological-Structure Modulated Polymer Nanocomposites Exhibiting Highly Enhanced Dielectric Strength and Energy Density. Adv. Funct. Mater. 2014, 24 (21), 3172–3178.

(29)

Feng, H.; Ma, W.; Cui, Z.-K.; Liu, X.; Gu, J.; Lin, S.; Zhuang, Q. Core/shell-Structured Hyperbranched Aromatic Polyamide Functionalized Graphene Nanosheets-Poly(p-Phenylene Benzobisoxazole) Nanocomposite Films with Improved Dielectric Properties and Thermostability. J. Mater. Chem. A 2017, 5 (18), 8705–8713.

(30)

Ameli, A.; Nofar, M.; Park, C. B.; Pötschke, P.; Rizvi, G. Polypropylene/carbon Nanotube Nano/microcellular Structures with High Dielectric Permittivity, Low Dielectric Loss, and Low Percolation Threshold. Carbon N. Y. 2014, 71, 206–217.

(31)

Yang, Y.; Gupta, M. C.; Dudley, K. L.; Lawrence, R. W. Novel Carbon Nanotube - Polystyrene Foam Composites for Electromagnetic Interference Shielding. Nano Lett. 2005, 5 (11), 2131–2134.

(32)

Xu, X. Bin; Li, Z. M.; Shi, L.; Bian, X. C.; Xiang, Z. D. Ultralight Conductive Carbon-NanotubePolymer Composite. Small 2007, 3 (3), 408–411.

(33)

Thomassin, J.-M.; Pagnoulle, C.; Bednarz, L.; Huynen, I.; Jérôme, R.; Detrembleur, C. Foams of polycaprolactone/MWNT Nanocomposites for Efficient EMI Reduction. J. Mater. Chem. 2008, 18 (7), 792–796.

(34)

Ameli, A.; Jung, P. U.; Park, C. B. Through-Plane Electrical Conductivity of Injection-Molded Polypropylene/carbon-Fiber Composite Foams. Compos. Sci. Technol. 2013, 76, 37–44.

(35)

Ameli, A.; Jung, P. U.; Park, C. B. Electrical Properties and Electromagnetic Interference Shielding Effectiveness of Polypropylene/carbon Fiber Composite Foams. Carbon N. Y. 2013, 60, 379–391.

(36)

Ameli, A.; Nofar, M.; Wang, S.; Park, C. B. Lightweight Polypropylene/stainless-Steel Fiber Composite Foams with Low Percolation for Efficient Electromagnetic Interference Shielding. ACS Appl. Mater. Interfaces 2014, 6 (14), 11091–11100.

(37)

Hamidinejad, S. M.; Chu, R.; Zhao, B.; Park, C. .; Filleter, T. Enhanced Thermal Conductivity of Graphene Nanoplatelet-Polymer Nanocomposites Fabricated via Supercritical Fluid Assisted InSitu Exfoliation. ACS Appl. Mater. Interfaces 2018, 10 (1), 1225−1236. Nguyen, Q. T.; Baird, D. G. An Improved Technique for Exfoliating and Dispersing Nanoclay

(38)



(39)

Particles into Polymer Matrices Using Supercritical Carbon Dioxide. Polymer (Guildf). 2007, 48 (23), 6923–6933. Okamoto, M.; Nam, P. H.; Maiti, P.; Kotaka, T.; Nakayama, T.; Takada, M.; Ohshima, M.; Usuki, A.; Hasegawa, N.; Okamoto, H. Biaxial Flow-Induced Alignment of Silicate Layers in Polypropylene/Clay Nanocomposite Foam. Nano Lett. 2001, 1 (9), 503–505.

(40)

Yuan, M.; Turng, L.-S. Microstructure and Mechanical Properties of Microcellular Injection Molded Polyamide-6 Nanocomposites. Polymer (Guildf). 2005, 46 (18), 7273–7292.

(41)

Shen, B.; Li, Y.; Zhai, W.; Zheng, W. Compressible Graphene-Coated Polymer Foams with Ultralow Density for Adjustable Electromagnetic Interference (EMI) Shielding. ACS Appl. Mater. Interfaces 2016, 8 (12), 8050–8057.

(42)

Stefanescu, E. A.; Tan, X.; Lin, Z.; Bowler, N.; Kessler, M. R. Multifunctional PMMA-Ceramic Composites as Structural Dielectrics. Polymer (Guildf). 2010, 51 (24), 5823–5832.

(43)

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 (43), 5104–5108.

(44)

Xu, X.; Park, C. B. Effects of the Die Geometry on the Expansion of Polystyrene Foams Blown with Carbon Dioxide. J. Appl. Polym. Sci. 2008, 109 (5), 3329–3336.

(45)

Leung, S. N.; Wong, A.; Wang, L. C.; Park, C. B. Mechanism of Extensional Stress-Induced Cell Formation in Polymeric Foaming Processes with the Presence of Nucleating Agents. J. Supercrit. Fluids 2012, 63, 187–198.

(46)

Tabatabaei, A.; Barzegari, M. R.; Mark, L. H.; Park, C. B. Visualization of Polypropylene’s StrainInduced Crystallization under the Influence of Supercritical CO2 in Extrusion. Polym. (United Kingdom) 2017, 122, 312–322.

(47)

Rizvi, A.; Chu, R. K. M.; Lee, J. H.; Park, C. B. Superhydrophobic and Oleophilic Open-Cell Foams from Fibrillar Blends of Polypropylene and Polytetrafluoroethylene. ACS Appl. Mater. Interfaces 2014, 6 (23), 21131–21140. Rizvi, A.; Tabatabaei, A.; Barzegari, M. R.; Mahmood, S. H.; Park, C. B. In Situ Fibrillation of CO2 -Philic Polymers : Sustainable Route to Polymer Foams in a Continuous Process. Polymer (Guildf). 2013, 54 (17), 4645–4652.

(48)

(49)

(50)

Shaayegan, V.; Ameli, A.; Wang, S.; Park, C. B. Experimental Observation and Modeling of Fiber Rotation and Translation during Foam Injection Molding of Polymer Composites. Compos. Part A Appl. Sci. Manuf. 2016, 88, 67–74. Park, C. B.; Behravesh, A. H.; Venter, R. D. Low Density Microcellular Foam Processing in Extrusion Using CO2. Polym. Eng. Sci. 1998, 38 (11), 1812–1823.

(51)

Behravesh, A. H.; Park, C. B.; Lee, E. K. Formation and Characterization of Polyethylene Blends for Autoclave-Based Expanded-Bead Foams. Polym. Eng. Sci. 2010, 50 (6), 1161–1167.

(52)

Matsumoto, M.; Saito, Y.; Park, C.; Fukushima, T.; Aida, T. Ultrahigh-Throughput Exfoliation of Graphite into Pristine “single-Layer” Graphene Using Microwaves and Molecularly Engineered Ionic Liquids. Nat. Chem. 2015, 7 (9), 730–736.

(53)

Prolongo, S. G.; Moriche, R.; Sánchez, M.; Ureña, A. Self-Stratifying and Orientation of Exfoliated Few-Layer Graphene Nanoplatelets in Epoxy Composites. Compos. Sci. Technol. 2013, 85, 136– 141.

(54)

Ellingham, T.; Duddleston, L.; Turng, L. S. Sub-Critical Gas-Assisted Processing Using CO2 Foaming to Enhance the Exfoliation of Graphene in Polypropylene + Graphene Nanocomposites. Polym. (United Kingdom) 2017, 117, 132–139. Yasmin, A.; Luo, J. J.; Daniel, I. M. Processing of Expanded Graphite Reinforced Polymer

(55)


Page 30 of 32

Page 31 of 32 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


Nanocomposites. Compos. Sci. Technol. 2006, 66 (9), 1179–1186. (56)

Araby, S.; Zaman, I.; Meng, Q.; Kawashima, N.; Michelmore, A.; Kuan, H.-C.; Majewski, P.; Ma, J.; Zhang, L. Melt Compounding with Graphene to Develop Functional, High-Performance Elastomers. Nanotechnology 2013, 24 (16), 165601.

(57)

Wakabayashi, K.; Pierre, C.; Diking, D. A.; Ruoff, R. S.; Ramanathan, T.; Catherine Brinson, L.; Torkelson, J. M. Polymer - Graphite Nanocomposites: Effective Dispersion and Major Property Enhancement via Solid-State Shear Pulverization. Macromolecules 2008, 41 (6), 1905–1908.

(58)

de Sousa Pais Antunes, M.; Gedler, G.; Velasco Perero, J. I. Multifunctional Nanocomposite Foams Based on Polypropylene with Carbon Nanofillers. J. Cell. Plast. 2013, 49 (3), 259–279.

(59)

Pu, N. W.; Wang, C. A.; Sung, Y.; Liu, Y. M.; Ger, M. Der. Production of Few-Layer Graphene by Supercritical CO2 Exfoliation of Graphite. Mater. Lett. 2009, 63 (23), 1987–1989.

(60)

Zhao, H.; Zhao, G.; Turng, L.-S.; Peng, X. Enhancing Nanofiller Dispersion Through Prefoaming and Its Effect on the Microstructure of Microcellular Injection Molded Polylactic Acid/Clay Nanocomposites. Ind. Eng. Chem. Res. 2015, 54 (28), 7122–7130.

(61)

Zhamu, A.; Jang, B. Z. Supercritical Fluid Process for Producing Nano Graphene Platelets. US 2010/0044646 A1, 2010.

(62)

David Kaschak, Robert Reynolds, Daniel Krassowski, B. F.; David M. Kaschak. GRAPHITE INTERCALATION AND EXFOLLATION PROCESS. US 7,105,108 B2, 2006. Antunes, M.; Mudarra, M.; Velasco, J. I. Broad-Band Electrical Conductivity of Carbon NanofibreReinforced Polypropylene Foams. Carbon N. Y. 2011, 49 (2), 708–717. Mahmoodi, M.; Arjmand, M.; Sundararaj, U.; Park, S. The Electrical Conductivity and Electromagnetic Interference Shielding of Injection Molded Multi-Walled Carbon Nanotube/polystyrene Composites. Carbon N. Y. 2012, 50 (4), 1455–1464.

(63) (64)

(65)

Arjmand, M.; Mahmoodi, M.; Park, S.; Sundararaj, U. An Innovative Method to Reduce the Energy Loss of Conductive Filler/polymer Composites for Charge Storage Applications. Compos. Sci. Technol. 2013, 78, 24–29.

(66)

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 (11), 2327–2338.

(67)

Wang, B.; Liang, G.; Jiao, Y.; Gu, A.; Liu, L.; Yuan, L.; Zhang, W. Two-Layer Materials of Polyethylene and a Carbon Nanotube/cyanate Ester Composite with High Dielectric Constant and Extremely Low Dielectric Loss. Carbon N. Y. 2013, 54, 224–233.

(68)

Vo, L. T.; Anastasiadis, S. H.; Giannelis, E. P. Dielectric Study of Poly(styrene-Co-Butadiene) Composites with Carbon Black, Silica, and Nanoclay. Macromolecules 2011, 44 (15), 6162–6171. Arbatti, M.; Shan, X.; Cheng, Z.-Y. Ceramic–Polymer Composites with High Dielectric Constant. Adv. Mater. 2007, 19 (10), 1369–1372.

(69)



Table of Content


Page 32 of 32

Ultralight Microcellular PolymerâGraphene Nanoplatelet Foams with

Recommend Documents

Ultralight Microcellular PolymerâGraphene Nanoplatelet Foams with