Controlled Synthesis of Poly(vinylamine)-Based Copolymers by Organometallic-Mediated Radical Polymerization

Abstract

Living/controlled polymerization methods have enabled the synthesis of numerous (co)polymers with defined compositions and architectures. However, the precision design of poly(vinylamine)-based copolymers remains challenging despite their extensive use in various fields of applications and the clear benefits to finely tune their properties. Here, we report on a two-step strategy for the synthesis of tailor-made poly(vinylamine) derivatives through the organometallicmediated radical (co)polymerization (OMRP) of N-vinylacetamide and/or N-methylvinylacetamide followed by acid hydrolysis of the acetamide groups. A series of well-defined homopolymers as well as statistical and block copolymers with pendant primary and/or secondary amines having controlled molar masses, compositions, and low dispersities were produced accordingly. The reactivity ratios of the comonomers as well as the composition drift along the chain were determined in order to have a precise idea of the polymer structures. These advances represent a significant step toward an efficient platform for synthesis of this important class of amino group-containing (co)polymers.

Poly(N‐methylvinylamine)‐Based Copolymers for Improved Gene Transfection

“…According to the OMRP mechanism, the cobalt complex limits the extent of irreversible termination reactions via reversible deactivation of the radical poly( N ‐vinylamide) chains . As described elsewhere, the controlled NVA/NMVA copolymerization was performed at 40 °C in methanol using a preformed alkylcobalt (III) complex (RCo) initiator. Varying the monomer feed composition ([NVA] 0 /[NMVA] 0 ) gave access to a series of P(NMVA‐ co ‐NVA) copolymers with different compositions ranging from 46% to 73% of primary acetamido groups as determined by 1 H NMR (Table , entries 8–14 and Figure S1 in the Supporting Information for 1 H NMR spectra).…”

“…In order to obtain the desired pendant amino groups, the polyvinylacetamido precursors were hydrolyzed using two conditions. The first one called soft condition, (2 n HCl, 120 °C, 14 h) reported by Akashi et al, led to copolymers having a global degree of deacetylation between 76% and 83%, while the second condition, (6 n HCl, 120 °C, 64 h) referred to as harsh conditions, gave global degree of deacetylation between 87% and 92% depending on the copolymer composition, i.e., the ratio between the primary and secondary amides . The hydrolysis level was confirmed by 1 H NMR (Figure S1, Supporting Information) and the final composition of the copolymers was determined by EA (Table S1, Supporting Information).…”

“…The acid digestion vessel (23 mL) used for hydrolysis reactions was purchased from Parr. PNVA homopolymer was prepared by photoinitiated OMRP as reported before . lPEI of M w = 22 kDa was prepared as described before …”

“…According to Dréan et al, a solution of alkyl–cobalt (III) initiator ([Co(acac) 2 (CH(OCOCH 3 )CH 2 ) ≈4 R 0 ] in CH 2 Cl 2 ) (1.30 mL of a 0.15 m stock solution, 0.195 mmol) was introduced in a flask under argon and evaporated to dryness under reduced pressure at room temperature. Distilled NMVA (6.0 mL, 58 mmol) was added under argon into the flask and the polymerization mixture was stirred at 40 °C.…”

“…PMVAms were readily obtained by free radical polymerization (FRP) of N ‐methylvinylacetamide (NMVA), followed by acidic hydrolysis of the amide groups . A series of PMVAms with controlled molar masses and low molar mass distribution prepared by organometallic mediated radical polymerization (OMRP) of NMVA and subsequent acidic hydrolysis was tested . We also found that the molar mass and the distribution of the PMVAm had a negligible impact on the transfection efficiency.…”