*Review* **Systematic Review on the E** ff**ects, Roles and Methods of Magnetic Particle Coatings in Magnetorheological Materials**

**Siti Khumaira Mohd Jamari 1, Nur Azmah Nordin 1,\*, Ubaidillah 2,\*, Siti Aishah Abdul Aziz 1, Nurhazimah Nazmi 1 and Saiful Amri Mazlan 1**


**\*** Correspondence: nurazmah.nordin@utm.my (N.A.N.); ubaidillah\_ft@sta ff.uns.ac.id (U.)

Received: 25 October 2020; Accepted: 23 November 2020; Published: 24 November 2020

**Abstract:** Magnetorheological (MR) material is a type of magneto-sensitive smart materials which consists of magnetizable particles dispersed in a carrier medium. Throughout the years, coating on the surface of the magnetic particles has been developed by researchers to enhance the performance of MR materials, which include the improvement of sedimentation stability, enhancement of the interaction between the particles and matrix mediums, and improving rheological properties as well as providing extra protection against oxidative environments. There are a few coating methods that have been employed to graft the coating layer on the surface of the magnetic particles, such as atomic transfer radical polymerization (ATRP), chemical oxidative polymerization, and dispersion polymerization. This paper investigates the role of particle coating in MR materials with the e ffects gained from grafting the magnetic particles. This paper also discusses the coating methods employed in some of the works that have been established by researchers in the particle coating of MR materials.

**Keywords:** magnetorheological; smart materials; coating; particle coating
