bài giảng living polymerization

LIVING POLYMERIZATION Hà Thúc Huy Khoa Hóa - ĐHKHTN Cao học Hóa Lý Tổng hợp & Biến tính poloymer Polymers in everday use • Mechanical properties • New applications • Personal care products • Pharmaceutical Applications • BASF, Unilever, Geltex, Avecia, etc Control over Polymer architecture • Graft Copolymers • Star copolymers • Dendrimers • Non covalent crosslinking • Branching • Narrow MWD • Blocks Control • Molecular Weight (Chain Length and Polydispersity) • Chain Architecture (Block, Comb, etc) • Functionality • Rate / Exotherm X Y Macromonomer Telechelic Block Graft Radical reactions P 1 P 2 + P 1 P 2 P 1 P 2 + P M P M P S P S P Px Px P + + + + + + ? Test for Living Polymerisation 0 20 40 60 80 100 Mn % Conversion kp[Pol*] ln [M] 0 /[M] time Living Polymerisation • Anionic • Cationic • Ring Opening Living Polymerisation • Rate of termination ∼ 0 • Rate of Initiation > Rate of Propagation • PDi (Mw/Mn) = 1 + 1/DP Living systems *constant number of polymer chains *no permanent chain stopping reactions *dormant and active state *control of chain-growth *narrow MWD (Poisson) *<Mn> vs. monomer conversion is linear Living Polymerisation ◊ No Termination ◊ No Chain Transfer INITIATION I* + M → IM* k i PROPAGATION IM* + M → IMM* k p1 IM n * + M → IM n M* k pn [...]... a plot of Mn vs % Conversion is linear for a living polymerisation If Rate of initiation (Ri) ≈ or > Rate of Propagation (Rp) and both Ri and Rp > Rate of termination (Rt) (Ideally Rt = 0) Then PDi (MWD, Mn/Mw) is narrow and a Poisson distribution PDi = 1+1/[DPn] e.g For a polymer with DPn = 100, PDi = 1.01 ATRP ATOM TRANSFER RADICAL POLYMERIZATION Living Polymerization Mn [M]0 Mn= Conversion • Mn •... anything with a double bond - Wide range of operating conditions - Aqueous Media: Emulsion polymerisation • Disadvantages • Highly non-selective reaction Non-trivial product control Living and Controlled Polymerisations • Living systems – constant number of polymer chains – no permanent chain stopping reactions – dormant and active state – control of chain-growth – narrow MWD (Poisson) – vs monomer . industrially • Advantages: - Very Robust Technique - Wide range of monomers and functionality’s Almost anything with a double bond - Wide range of operating conditions - Aqueous Media: Emulsion. Emulsion polymerisation • Disadvantages • Highly non-selective reaction Non-trivial product control Living and Controlled Polymerisations • Living systems – constant number of polymer chains – no. LIVING POLYMERIZATION Hà Thúc Huy Khoa Hóa - ĐHKHTN Cao học Hóa Lý Tổng hợp & Biến tính poloymer Polymers in everday