This paper presents the preparation of polystyrene functionalized TiO2 nanoparticles using the reversible addition fragmentation chain transfer (RAFT) polymerization. The surface of TiO2 NPs with an average particle size of about 5 nm was modified by S-benzyl S’- trimethoxysilylpropyltrithiocarbonate in order to obtain the RAFT agent functionalized TiO2 NPs (TiO2-RAFT). | Journal of Science and Technology 54 (1A) (2016) 292-299 CONSTRUCTING POLYSTYRENE BRUSHES ON TIO2 NANOPARTICLES BY IN SITU REVERSIBLE ADDITION FRAGMENTATION CHAIN TRANSFER POLYMERIZATION Long Giang Bach1*, Bui Thi Phuong Quynh1, Kwon Taek Lim2 1 NTT Institute of Hi-Technology, Nguyen Tat Thanh University, 300A Nguyen Tat Thanh, Ho Chi Minh City, Vietnam 2 Pukyong National University, Busan, 608-737, Republic of Korea * Email: blgiangntt@ Received: 19 September 2015; Accepted for publication: 26 October 2015 ABSTRACT This paper presents the preparation of polystyrene functionalized TiO2 nanoparticles using the reversible addition fragmentation chain transfer (RAFT) polymerization. The surface of TiO2 NPs with an average particle size of about 5 nm was modified by S-benzyl S’trimethoxysilylpropyltrithiocarbonate in order to obtain the RAFT agent functionalized TiO2 NPs (TiO2-RAFT). Subsequently, styrene was radically polymerized through the immobilized RAFT agent on the silica surface, in the presence of 2,2’-azobisisobutylnitrile (AIBN) as an initiator, to achieve the TiO2-g-PS nanocomposite. The characteristics of the as-synthesized nanocomposite were determined using FT-IR, EDX, XPS, TGA, XRD, TEM and SEM analyses. Keywords: TiO2 nanoparticles, TiO2-g-PS, RAFT polymerization. 1. INTRODUCTION The development of multifunctional nanomaterials has attracted huge attention for applications in various areas including electronics, optics, biomedicine, and renewable energy generation [1 - 3]. However, because of their extremely large surface-area/volume ratio, nanoparticles are vulnerable to agglomeration thus often resulting in decreased desired properties. Recent research has shown that the encapsulation of inorganic particles by polymer can create advanced materials possessing not only better resistance against aggregation but also improved optical properties and surface chemistry [4 - 5]. As an important nanomaterial, TiO2 nanoparticles (TiO2 NPs) have .