Electrorheological properties of polyimide nanoparticles suspensions Alexander Danilin a,b , Kamila Kydralieva b , Nikolay Semenov a , Elena Kelbysheva a,⇑ a Institute of Applied Mechanics, Russian Academy of Sciences, Leningradskiy ave., 7, Moscow 125040, Russia b Moscow Aviation Institute (National Research Institute), Volokolamskoe shosse, 4, Moscow 125993, Russia article info Article history: Received 1 October 2019 Received in revised form 28 February 2020 Accepted 3 March 2020 Available online xxxx Keywords: Electrorheological suspensions Polyimides Electric field Viscosity Functional polymer Polymer with sulfo-acid group abstract Suspensions of polyimide particles were obtained, in which 2,5-diaminobenzenesulfonic acid was used as a diamine component. Their electrorheological properties in a nonconducting medium were studied depending on the parameters of deformation and the intensity of the external electric field. It is estab- lished that the electro-rheological suspensions obtained based on particles of polyimide PI-I–PI-IV have a powerful electro-rheological response, ten times higher than the electro-rheological effect of suspen- sions based on traditional micro-sized particles of the dispersed phase. Ó 2020 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the 12th International Conference on Composite Science and Technology. 1. Introduction Electrorheological suspensions (ERS) are materials that under the influence of an external electric field undergo rapid and rever- sible changes in their rheological properties (viscosity, yield strength, shear modulus, etc.) [1–4]. When an electric field is applied, a low-viscosity and the fluid medium are able to exhibit the properties of a viscoplastic object. Such transformations are reversible and occur within milliseconds. Therefore, ERS is of con- siderable interest for use in various technical systems. This allows referring them to the so-called ‘‘intellectual materials” [1], the properties of which can be adjusted depending on the practical task. It is important to choose such polyimide structures that are well soluble, are non-hydrolyzable and can be used in the form of cast films. Another advantage of the polyamide chain is the ease of polymerization and the commercial availability of various aro- matic diamines and acid dianhydrides. ERS is usually composed of polarizing solids dispersed in non-conductive oil. When an external electric field is applied, the particles are polarized and form a chain structure along the field direction. It was previously shown [4] that one of the most frequently investigated dispersed phases in ERS is polyimides [5]. This class of polymers is also promising because it has high thermal stability [6], mechanical strength, flexibility, and chemical stability. Polyimide particles ERS were obtained based on a series of aro- matic polyimides synthesized by the single-stage high- temperature polycondensation method on the basis of 4,4 0 -diami nodiphenylsulfide and 2,5-diaminobenzenesulfonic acid with dif- ferent dianhydrides phenyltetracarboxylic acids. The structure and size of polyimide nanoparticles were studied and character- ized by methods IR and Dynamic light scattering and others. Their electrorheological properties were investigated in nonconducting medium depending on parameters of deformation and external electric field intensity. 2. Experimental Materials and methods. The primary materials for the poly- merization – dianhydrides: 3,3 0 ,4,4 0 -benzophenonetetracarboxylic dianhydride, 1,2,4,5-benzenetetracarboxylic acid dianhydride, 4,4 0 - oxydiphtalic dianhydride, 4,4 0 -(isopropylidene)diphthalic dianhy- dride, 2,5-diaminobenzenesulfonic acid, polymethylsiloxane-500 were purchased from Sigma-Aldrich were used without purifica- tion. IR spectra were recorded on a Tensor 37 (Bruker) IR Fourier spectrometer with a resolution of 2 cm 1 in KBr. The study of the electrorheological properties was carried out on the basis of the Rheostress RS 150 reoviscometer (HAAKE Germany) with a measuring unit of the plane-plane type. The PI powder was dried by vacuum oven in temperature 60 °C. At the https://doi.org/10.1016/j.matpr.2020.03.049 2214-7853/Ó 2020 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the 12th International Conference on Composite Science and Technology. ⇑ Corresponding author. E-mail address: kellena80@mail.ru (E. Kelbysheva). URL: https://iam.ras.ru/ (E. Kelbysheva). Materials Today: Proceedings xxx (xxxx) xxx Contents lists available at ScienceDirect Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr Please cite this article as: A. Danilin, K. Kydralieva, N. Semenov et al., Electrorheological properties of polyimide nanoparticles suspensions, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2020.03.049