Sythesis Of PCL-based Graft Copolymers And Its Applications

1. In this paper, a small molecule reversible addition fragmentation chaintransfer (RAFT) agent with two carboxyl groups was synthesized. Then,Polycaprolactone (PCL) with trithiocarbonate side group (PCL-TTC) was preparedby step-growth polymerization. Finaly, PCL-TTC was used as macro-RAFT agentto initiate styrene (St), methacrylate (MA), N-isopropyl acrylamide monomer(NIPAAm) via RAFT graft polymerization, and PCL-g-PS, PCL-g-PMA andPCL-g-PNIPAAm was obtained respectively. The products were characterized byFourier transform infrared spectroscopy (FT-IR), gel permeation chromatograph(GPC) and1H nuclear magnetic resonance (1H NMR). Moreover, the product withsulfydryl end group of the grafted chains was obtained by the aminolysis of graftcopolymer and reversible gel was prepared successfully by redox of sulfydrylgroup.2. The PCL macromolecular RAFT chain transfer agent with dithioester sidegroup (PCL-DTE) was prepared via condensation polymerization between hydroxylgroup of PCL and carboxyl group of α-succinic dithiobenzoate under lowtemperature. Then, PCL-DTE was used to initiate St monomer via RAFT graftpolymerization, and the resultant was PCL-g-PS. Moreover, PCL-g-PS was used ascompatibilizer for PS/PCL melt blends. The results of rheological properties,mechanical properties, thermal gravimetric analysis (TGA), differential scanningcalorimetry (DSC), vicat softening point (VSP), scanning electron microscopy(SEM) measurements showed that, PCL-g-PS made PCL disperse morehomogeneously in PS matrix, which resulted in better mechanical properties,toughness and thermal stability of PS/PCL/PCL-g-PS blends than those of PS/PCLblends.3. The PCL macromolecular RAFT chain transfer agent with xanthate side groups(PCL-xanthate) was prepared via condensation polymerization between hydroxylgroup of PCL and carboxyl group of n-butyl xanthate. The resulting PCL-xanthatewas used in RAFT gaft polymerization of vinyl acetate (VAc), and PCL-g-PVAcwas prepared. It was used as a compatibilizer for PLA/PCL melt blends.Rheological properties, mechanical properties, X-ray Diffraction (XRD), TGA,DSC, VSP, SEM results showed that PCL was more homogeneously dispersed inPLA matrix because of PCL-g-PVAc, so the rheological properties, mechanical properties, toughness and thermal stability of PLA/PCL/PCL-g-PVAc blends weresuperior to those of PLA/PCL blends.