Synthesis of poly(vinyl laurate)‐b‐poly(vinyl stearate) diblock copolymers by cobalt‐mediated radical polymerization in solution

Abstract

Poly(vinyl laurate) (PVL) and poly(vinyl stearate) (PVS) were synthesized by means of cobalt‐mediated radical polymerization (CMRP). Cobalt(II) diacetylacetonate (Co(acac)2) was demonstrated to control the radical polymerization of these monomers in solution. Molecular weights up to 15,000 g·mol−1 were obtained with reasonably low polydispersity indices (PDI < 1.3). The efficiency of the redox initiator [lauroyle peroxide (LPO)/citric acid (CA)] was found to be low (around 10%) as already reported for vinyl acetate. The solvent and temperature were found to have a very weak influence on the initiator efficiency. It appeared that CA played no role in the initiation process that only involved a redox reaction between LPO and Co(acac)2. PVL‐b‐PVS diblock copolymers could be synthesized using two strategies: (1) Sequential addition, that is, addition of the second monomer (VS) at high conversion of the first one (VL). (2) Macroinitiator technique, that is, isolation of a PVL macroinitiator then polymerization of VS from this cobalt functionalized macroinitiator. Both techniques allowed the synthesis of diblock copolymers with molar masses around 25,000 g·mol−1 and PDI lower than 1.4. The resulting materials were characterized by DSC, revealing that both blocks exhibit side‐chain crystallinity and phase segregate in the bulk. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Organometallic mediated radical polymerization of vinyl acetate using bis(imino)pyridine vanadium trichloride complexes

“…One very recent literature report utilizes Co(acac) 2 to generate homopolymers and block co-polymers of VLa and VSt with good control (PDI < 1.3), using a redox initiator. 54 Conversions for the screening reactions of VLa using 1 were limited to 16% conversion at 120 °C, initiated by AIBN, despite reaction times as long as 64 h (Table 7). Control is modest when the polymerizations are carried out in bulk, with broadened PDIs of 1.5-1.6.…”

RAFT Polymerization of Vinyl Esters: Synthesis and Applications

“…The advent of reversible-deactivation radical polymerization [28] has led to an increased interest in poly(vinyl ester)s by enabling the control of the main characteristics of polymer chains such as molar mass and molar mass distribution, end-groups and architecture. Numerous recent studies have focused on complex polymer architectures with original solid state morphologies [30][31][32][33], PVA-based surfactants [34,35] or poly(vinyl ester)s with enhanced solubility in scCO 2 [3][4][5][6][7][8]. To date, iodine-transfer polymerization (ITP) [36], organoheteroatom-mediated polymerization (OMRP) [28,37], cobalt-mediated polymerization (CoMRP) [38] and reversible addition-fragmentation chain transfer (RAFT) polymerization [39] have been proven efficient in the radical polymerization of vinyl esters.…”

RAFT/MADIX (co)polymerization of vinyl trifluoroacetate: a means to many ends

“…This can be at least partly explained by the revealed chain transfer to solvent. In addition, formation of head-to-head adducts and/or to a lesser extent chain transfer to monomer/polymer as in the case of VAc 29,55 may contribute to this increase of dispersities although no related literature could be found on the polymerizability of PVTFAc in order to support our assumptions. A deeper study of free-radical polymerization of VTFAc is underway in our group in order to better understand the observed evolution of dispersities.…”

“…As a result, the advances in reversible-deactivation radical polymerization (RDRP) 21 have somewhat rejuvenated the eld of poly(vinyl esters) through controlling the main macromolecular characteristics of polymer chains such as chain length, end functionalization, dispersity and architecture. Studies focusing on complex polymer architectures based on poly(vinyl esters) and PVA, 22 like PVAbased surfactants, 23,24 "graing to" techniques, 25 original solid state morphologies [26][27][28][29] or poly(vinyl esters) with higher solubilities in sc-CO 2 , [3][4][5] have been reported thereaer. In recent years, new technologies have actually allowed investigation of the polymerization of less-activated monomers (LAMs) such as vinyl esters.…”