Subscriber access provided by UNIV OF DURHAM
Materials and Interfaces
Enhanced Comprehensive Properties of Nylon6 Nanocomposites by Aniline Modified Boron Nitride Nanosheets Zhujun Wang, Qian Li, Zheming Chen, jinfeng liu, Tengfei Liu, Huayi Li, and Shuirong Zheng Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.8b02005 • Publication Date (Web): 27 Jul 2018 Downloaded from http://pubs.acs.org on July 31, 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 26 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
Industrial & Engineering Chemistry Research
Enhanced Comprehensive Properties of Nylon6 Nanocomposites by Aniline Modified Boron Nitride Nanosheets Zhujun Wang,ab Qian Li,a Zheming Chen,a Jinfeng Liu,a Tengfei Liu,a Huayi Li*,a and Shuirong Zhengb a. Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Engineering Plastics Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China b. Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education, Northwestern Polytechnical University, Xi'an, Shaanxi, 710129, P. R. China * E-mail:
[email protected] Abstract To improve the effective thermal conductivity of hexagonal Boron nitride (h-BN) in polymer matrix, surface modification upon it could be a usual and efficient method. Boron nitride nanosheets (BNNSs) were abundantly decorated by amino groups via a two-step reaction. The pre-hydroxylation of BNNSs in a concentrated base environment could increase the active reaction sites on the surface of BNNSs, so that aniline carbocations produced by the hydrolysis of the diazonium salt were utilized to achieve a high grafting content of aniline groups onto the surface of modified BNNSs (A-BNNSs). During melt blending, chemical reactions between A-BNNSs and carboxyl groups of PA6 chains benefited the interfacial force between A-BNNSs and PA6 matrix, thus the distribution of A-BNNSs in PA6 matrix was enhanced. Consequently, the prepared PA6/A-BNNSs nanocomposites owned an improved thermal
ACS Paragon Plus Environment
Industrial & Engineering Chemistry Research 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
conductivity, better thermal stability and enhanced mechanical properties compared with the PA6/BNNSs nanocomposites at the same filler content. Especially, as for PA6/A-BNNSs nanocomposites with 20 wt.% filler loading, its thermal conductivity was 2.886 W·m-1·K-1, nearly 10 times that of pure PA6 and its initial decomposition temperature was nearly 100 °C higher than that of pure PA6, which would be a popular candidate for thermal conductivity field. Keywords: Boron nitride; nylon6; modification; thermal properties; mechanical properties.
1. Introduction Polymers possess light weight, high specific strength and modulus, excellent electrical insulating properties, good processability, excellent chemical stability, and have been widely applied in the fields of electronics1, biology2, energy3 and manufacturing industry4, etc.
ACS Paragon Plus Environment
Page 2 of 26
Page 3 of 26 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
Industrial & Engineering Chemistry Research
Unfortunately, the intrinsic low thermal conductive (λ) and insufficient thermal stability of polymer matrix have restricted its broader application in the areas which require good heat dissipation and low thermal expansion. For enhancing the thermal conductivity of the polymer matrix, one convenient and effective method is to incorporate thermally conductive fillers5-6, such as silicon carbide (SiC)7, silicon nitride (Si3N4)8, silica (SiO2)9, boron nitride (BN)10-12, aluminum oxide (Al2O3)13-14, and aluminum nitride (AlN)15-16. Among those ceramic fillers, BNNSs17-18 are widely used in electronic circuit devices due to their high thermal conductivity (60 W·m-1·K-1), excellent thermal stability19 and chemical stable property20-21. However, the effective thermal conductivity of BNNSs is highly limited by their high surface energy and strong tendency to aggregate in the polymer matrix, which are fatal to properties of polymer composites22. Thus, surface modification of BNNSs is an important route to enhance the thermal conductivity of polymer composites. At present, there are several kinds of methods for surface modification of h-BNs, including non-covalent modification, covalent modification and solid-state surface modification. As for covalent modification, due to the good chemical stability of BNNSs, existing modification methods are often not quite effective to break the B-N bonds. Sainsbury et al. presented a covalent approach for functionalization of BNNSs by using
ACS Paragon Plus Environment
Industrial & Engineering Chemistry Research 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
oxygen radicals23. BNNSs were mixed with organic peroxide under at high temperatures and pressures to introduce hydroxyl groups. There were also some reports to disperse h-BNs into NaOH solutions and introduce the -OH on the surface of h-BNs thus to improve the dispersibility of h-BNs in the epoxy matrix for thermal conductivity and improved mechanical properties24-25. Shen et al. used polydopamine (PDA) to modify h-BN micro-platelets to prepare h-BN@PDA/PVA thermal conductivity composites26. The results showed that the thermal conductivity of h-BN@PDA/PVA composites with 10 vol.% filler was 5.4 W·m-1·K-1, which was about 1.5 times higher than that of h-BN/PVA composites at the same filler loading. Permal et al. functionalized BN nanoplatelets with (3-aminopropyl)triethoxysilane (KH550) to reduce the thermal interfacial resistance between fillers and epoxy matrix27. The resultant epoxy composites provided a higher thermal conductivity of 0.57 W·m-1·K-1 than that of neat epoxy (0.17 W·m-1·K-1). Zeng et al. reported a novel polymeric composites by infiltrating epoxy matrix into 3D-BNNS network that constructed by an ice templated method28. The obtained epoxy composites exhibited a high λ value of 2.85 W·m-1·K-1 and a low CTE of 24-32 ppm·K-1 at a relatively low BNNS loading (9.29 vol.%). The above-mentioned methods improved the compatibility between h-BN fillers and the polymer matrix by using different surface modification while the interaction between them only involved physical
ACS Paragon Plus Environment
Page 4 of 26
Page 5 of 26 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
Industrial & Engineering Chemistry Research
interaction. However, the method to modify BNNSs by imparting them functional groups that can react with polymer chains, which makes the blending process also involve chemical interaction to enhance the dispersibility of h-BN in polymer matrix, has rarely been reported. In this paper, BNNSs were selected as the thermally conductive filler, which were activated in a concentrated base environment to introduce a large number of B-OH and N-H functional groups. Afterwards, the highly reactive carbon-positive irons produced by the hydrolysis of diazonium salt were utilized to graft amino groups onto the surface of HO-BNNSs. PA6/A-BNNSs nanocomposites were prepared by melt blending. The reaction between the surface amino groups of A-BNNSs and the terminal carboxyl groups of PA6 molecular chains was verified. The distribution of A-BNNSs in PA6 matrix was analyzed in detail, and its effect on the thermal properties, thermal conductivity and mechanical properties of nanocomposites was further evaluated to illustrate the advantage of the A-BNNSs. 2. Experimental
2.1 Materials Nylon 6 (ABK) was purchased from BASF SE. Hexagonal boron nitride nanosheets (BNNSs) were purchased from Aladdin reagent (Shanghai) co. LTD. The reagents used for the synthesis of benzene diazonium chloride, including p-phenylenediamine, sodium nitrite (NaNO2), concentrated
ACS Paragon Plus Environment
Industrial & Engineering Chemistry Research 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 6 of 26
hydrochloric acid (HCl) and iron powder were purchased from J&K Scientific Ltd. All chemicals and reagents were used directly without further purification. Deionized water was generated by a Milli-Q integral ultrapure water purification system.
2.2 Surface chemical functionalization of BNNSs 2.2.1 Synthesis of HO-BNNSs Hydroxylation treatment of BNNSs was conducted and the method was based on one reported process29. In a concentrated base environment, the B-N bonds were broken by the high-temperature solid-phase method to produce a large number of B-OH and N-H groups. Firstly,1 g BNNSs, 2.8 g sodium hydroxide and 2.8 g potassium hydroxide were co-grounded and mixed. Then the mixed powder was moved to the hydrothermal reactor. The reaction was conducted at 180 ℃ for 5 h, following one-hour ultrasonic treatment. Finally, the product was centrifuged, purified and named as HO-BNNSs. The scheme was shown as Figure 1. OH H B N
B NH
H2N
NH
Broken HO B
B
B
HN
N
NH
B
B
B
HN
N
N
N
NH
B
B
B
OH
NaOH / KOH HN
N
N
B N H
B N
BNNSs
NH2
Broken B
BH N H
N
Broken
180℃ * 5h HB
B
HN
HO
B N H
OH
B N H2
B N H
OH
HO-BNNSs
Figure 1. Schematic representation for the hydroxylation of BNNSs
ACS Paragon Plus Environment
Page 7 of 26 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
Industrial & Engineering Chemistry Research
2.2.2 Synthesis of A-BNNSs The high activity of aniline-carbocations produced by the hydrolysis of diazonium salt was utilized to graft Ph-NH2 onto the surface of HO-BNNSs. Detail procedure was given as follow. Firstly, 1.6 g p-phenylenediamine was dissolved in 20 mL deionized water with an ice bath (
