Jean Claude Galin

New super-hairy semi-rigid polymers

Living monofunctional poly(tetramethylene oxyde) (PTMO) (THF bulk polymerization initiated at 20°C by methyl triflate) was end capped by reaction with 3-(dimethylamino)propyl isocyanide. Selective and quantitative quaternization of the tertiary amine function results in the straightforward synthesis of PTMO macromonomers of the isocyanide type with a fairly good control of molecular weight and polydispersity (M n = 1800-4400, M w /M n = 1.2). Their homopolymerization at 40°C in highly concentrated methanol solution (macromonomer weight fraction =0.80) initiated by NiCl 2 quantitatively yields the corresponding poly(macromonomers) of high degrees of polymerization (DP w > 10 3 ) and of very unusual and maximum branching density: one graft chain per every backbone carbon atom. According to a semi-quantitative analysis of their radius of gyration, as derived from light scattering measurements (EtOAc-iPrOH 9: 1 by vol., Et 4 N + CF 3 SO 3 - 0.05 M), an increase of the intrinsic rigidity (persistence length) of the worm-like poly(isonitrile) backbone induced by the PTMO branches cannot be ruled out. These super-hairy polymers may be considered as exotic comb-shaped cationic poly(amphiphiles) of potential interest as new lyotropic and thermotropic materials.

Hydrophilic graft polyacrylonitrile copolymers: 1. Synthesis and characterization in dilute solution

Abstract Radical copolymerization of methoxy-poly(ethylene glycol) monomethacrylate (A(8); M n ∼470 ), a water-soluble macromonomer, with acrylonitrile (B) was studied in homogeneous dimethylsulphoxide solution at 60°C in the following conditions: [A(8)]0+[B]0=0.5–1.5 mol l−1; molar fraction of A(8) in the monomer feed, f0A(8)⩽0.75. The process obeys the terminal unit model (rA(8)=1.35, rB=0.38), and readily yields graft copolymers over a broad range of composition and molecular weight (Mw∼(0.5–9.0)×105). The reactivity ratio of a macromonomer of higher molecular weight (A(21); M n ∼10 3 ) may be estimated to be about 0.66, a significantly larger value than those of the shorter-chain (A(8)) and ordinary alkyl methacrylates. Light scattering measurements in dimethylformamide (DMF) solution at room temperature only lead to apparent values of the second viral coefficient A2 and of the radius of gyration ( s 2 z ) 0.5 for these heterogeneous copolymers. Although DMF is a poorer solvent for the polyether than for polyacrylonitrile and in spite of the branched structure, the apparent dimensions of the copolymers seem only slightly lower than those of polyacrylonitrile of the same molecular weight.

Adsorption of an amphipatic copolymer on a kidney dialysis membrane

We have studied the adsorption of a copolymer of acrylonitrile and methacrylate of nonaethyleneglycol on a kidney dialysis membrane, which contains mostly nitrile groups. The kinetics study reveals at first a rapid increase of the adsorbance, followed by slow variations suggesting rearrangements at the interface. The isotherms do not present a true plateau at high concentration. The high adsorbance observed at low pH or high salt concentration could be related to the ability of polyethyleneoxide to form a complex with cations.

Free-Radical Copolymerization of Methyl Methacrylate and α-Methacrylophenone. I. Reactivity Ratios

Abstract The free-radical copolymerization of methyl methacrylate and methacrylophenone (MAP) initiated by azobisisobutyroni-trile at 60°C has been studied in ethylbenzene solution and in bulk. The process is characterized by a competitive Diels-Alder condensation of methacrylophenone and by a very low reactivity of methacrylophenone-terminated macroradicals in propagation reactions. The experimental composition data are consistent with a terminal unit model: rA = 1.77 ± 0.02, rB = 0.110 ± 0.006. Copolymerization with depropagation of methacrylophenone-terminated growing chains and copolymerization affected by penultimate effects have been tested as optimized possible models to take into account the inability of MAP to undergo homopolymerization.