YENİ NESİL FONKSİYONEL KOPOLİMER-RAFT AJAN/ORGANO-SİLİKAT NANOYAPILARININ SENTEZİ VE KARAKTERİZASYONU

Abstract

This thesis presents a new approach for the synthesis of polymer nanostructures using a bifunctional reversible addition-fragmentation chain transfer (RAFT) agent, two types of modified organo-montmorillonites, such as a non-reactive dimethyldodecyl ammonium (DMDA)-MMT and a reactive octadecylamine (ODA)-MMT organoclays, and a radical initiator. The thesis includes the following stages: (1) The synthesis of Poly(maleic anhydride-co-n-butylmethacrylate) copolymers by RAFT polymerization method with two different RAFT Agents (RAFT-1: S,S-bis(-dimethyl-’’-acetic acid)trithiocarbonate and RAFT-2: 2-Cyano-2-Propyl benzodithioate) and selection of proper RAFT agent for the nanocomposite synthesis. (2) The synthesis of RAFT intercalated DMDA-MMT and ODA-MMT’s by a physical or chemical interaction of the RAFT having two pendant carboxylic groups [S,S-bis(-dimethyl-’-acetic acid)trithiocarbonate] with surface alkyl amines of O-MMT containing tertiary ammonium cation or primary amine groups through strong H-bonding and complexing/amidization reactions, respectively. (3) Utilization of these well-dispersed and intercalated RAFT…DMDA-MMT and RAFT…ODA-MMT complexes and their amide derivatives as new modified RAFT agents in radical-initiated interlamellar controlled/living copolymerization of maleic anhydride (MA)-n-butylmethacrylate (BMA) and itaconic acid (IA)-n-butyl methacrylate (BMA) monomer pair. The structure and compositions of the synthesized RAFT…O-MMT complexes and functional copolymer/O-MMT nanocomposites were confirmed by FTIR, XRD, thermal (DSC-TGA), SEM and TEM morphology analyses. The results of the comparative analysis of the nanocomposites structure-composition-property relations show that all studied nanosystems have higher degree of exfoliation (%87,6-95,8) and the functional copolymer-organoclay hybrids prepared with reactive RAFT…ODA-MMT complex and containing a combination of predominantly exfoliated nano-structures (ID/ED %92,4-95,8), exhibit fine dispersed morphology. The nanocomposites which are prepared with RAFT…DMDA complexes with higher intercalation degree (ID/ED %85,3-91,0) show higher thermal stability, glass transition and melting temperatures than RAFT…ODA clay containing analogs with a completely exfoliated structures. IA-BMA nanocomposites show %20-25 higher thermal stability than copolymers and also nanocomposites have 18-35°C higher Tg and Tm values than copolymers. The results indicate that increasing concentration of BMA flexible linkages decrease crystallinity, glass-melt transition temperatures and provide a higher degree of exfoliation of nanocomposites due to the internal plasticizing effect of the BMA units during in-situ processing. This simple and versatile method can be applied to a wide range of functional monomer/comonomer systems and multifunctional RAFT compounds for preparation new generation of nanomaterials.