Synthesis and physicochemical characterization of block copolymers by using some new makro raft agents

Polymer is one of an important class of materials by from the view of academic and commercial. Depending on the synthesis methods, the polymers can be obtained in many different morphology. During the last decades, studies on the incorporation of nanomaterials with block copolymers have been studied by many researchers. Block/graft copolymers get much attention due to compatible with the nanotechnology that allow to work with multidisciplinary. Block/graft copolymers exhibit superior properties like to form the composite of bio-materials and nano-materials which provide wide range of applications. Polymers with low polydispersity are synthesized by controlled radical polymerization techniques, since polymers synthesized by free radical polymerization, have broad molecular weight distribution, non-controlled molecular weight and polymer structure. Over the past decade, Controlled/Living Radical Polymerization (CLRP) techniques such as Nitroxide Mediated Radical Polymerization (NMRP), Reversible Addition- Fragmentation Chain Transfer Polymerization (RAFT) and Atom Transfer Radical Polymerization (ATRP) have generated a great deal of attention because of its versatility in producing complex macromolecular architectures with pre-estimated molecular weights and very narrow polydispersity. Moreover, CLRP methods do not require strict purification of monomers and solvents and tolerate a variety of functional groups. For these reasons, they have more advantages than the ionic polymerization technique. N-isopropylacrylamide (NIPAM) is an extremely important nonionic acrylamido monomer and has been the subject of intensive research over the years. One of the reasons it has been so widely studied is that poly(N-izopropylacrylamide)( PNIPAM) possesses a readily accessible lower critical solution temperature (LCST) in water around ~32 °C. This is close to human body temperature (37 °C) and as such has, for example, been evaluated in drug delivery applications, bioseparations and catalyst recovery. In the first part of this work, Chain Transfer Agent were synthesized from S-Dodecyl-S '- (α, α'-dimethyl-α''-acetic acid) -thrithiocarbonate (DDMAT) (R-2) and S, S'-Bis (α, α'-dimethyl-α''-acetic acid) tritiocarbonate (BDATC) (R-1). In the second part, Macro RAFT agent was synthesized with the reaction of R-2 with polyethylene glycol (Mn: 2000 and 8000).The synthesized Macro RAFT agent was polymerized with NIPAM and MMA. Homopolymers of R-2 and 4-vinyl benzyl chloride, styrene, n-butyl methacrylate, tert-butyl methacrylate and N-isopropylacrylamide monomers were first synthesized. Block copolymers of 4-vinyl benzyl chloride, styrene, n-butyl methacrylate, tert-butyl methacrylate and N-isopropylacrylamide were then synthesized with the homopolymers obtained. Obtained graft copolymers with polyethylene glycol from vinyl ends of the Pvbc and styrene block copolymers were obtained. Swelling ratios and LCST values of PNIPAM polymer polymerized with macro RAFT agent were found. Styrene and vinyl benzyl chloride polymerisation kinetics were investigated. In addition, RAFT polymerisation random copolymers of styrene and vbc monomer. 2,2-azobisisobutyronitrile (AIBN) was used as the initiator. The DCC / DMAP pair was used as the catalyst. Toluene was used as the polymerization solvent. The macromolecule RAFT agent synthesized was then polymerized with poly methyl methacrylate monomer. The water release properties of the synthesized polymers were investigated at specific time intervals. The structures of the polymers were characterized by Fourier Transform Infrared Spectroscopy (FT-IR) and Proton Nuclear Magnetic Resonance Spectroscopy (1H-NMR). The glass transition temperature of homopolymer and copolymer were measured by Differential Scanning Calorimetry (DSC). Mw/Mn and avarage molecular weight of the polymers were determined using Gel Permation Chromatography (GPC). Broken surface images were made with Scanning Electron Microscopy (SEM).