Statistical Ring Opening Metathesis Copolymerization of Norbornene and Cyclopentene by Grubbs’ 1st-Generation Catalyst

Abstract

Statistical copolymers of norbornene (NBE) with cyclopentene (CP) were prepared by ring-opening metathesis polymerization, employing the 1st-generation Grubbs' catalyst, in the presence or absence of triphenylphosphine, PPh3. The reactivity ratios were estimated using the Finemann-Ross, inverted Finemann-Ross, and Kelen-Tüdos graphical methods, along with the computer program COPOINT, which evaluates the parameters of binary copolymerizations from comonomer/copolymer composition data by integrating a given copolymerization equation in its differential form. Structural parameters of the copolymers were obtained by calculating the dyad sequence fractions and the mean sequence length, which were derived using the monomer reactivity ratios. The kinetics of thermal decomposition of the copolymers along with the respective homopolymers was studied by thermogravimetric analysis within the framework of the Ozawa-Flynn-Wall and Kissinger methodologies. Finally, the effect of triphenylphosphine on the kinetics of copolymerization, the reactivity ratios, and the kinetics of thermal decomposition were examined.

Ring‐Opening Metathesis Copolymerization of Cyclopentene Above and Below Its Equilibrium Monomer Concentration

“…Past studies have demonstrated that cyclopentene (C) and norbornene (N) will copolymerize with a variety of ROMP catalysts, and typically N is preferentially enchained over C. [16][17][18][19][20][21][22] None of these studies intended to demonstrate that C units could be enchained below [C] eq (≈1.2 m at room temperature [23] ), although close examination of the experimental conditions reveals that this was the case for at least one successful C-N copolymerization. [20] In several cases, [17][18][19][20][21][22] reactivity ratios (r C and r N , [17,18,21,22] or the product r C r N [19,20] ) were determined as a means to quantify the copolymerization process, but all of these analyses employed the classical terminal model of copolymerization [24][25][26] (or the dyad distribution resulting therefrom), which does not include the possibility of depropagation of either unit. As we will show below, this can lead to very large (order-of-magnitude) errors in r C (the reactivity ratio for the reversibly propagating monomer), and to a qualitatively incorrect description of certain features of the copolymerization (e.g., the limiting conversion at which propagation ceases).…”

“…Past studies have demonstrated that cyclopentene (C) and norbornene (N) will copolymerize with a variety of ROMP catalysts, and typically N is preferentially enchained over C . None of these studies intended to demonstrate that C units could be enchained below [C] eq (≈1.2 m at room temperature), although close examination of the experimental conditions reveals that this was the case for at least one successful C–N copolymerization .…”

“…This approach has been used to generate gradient copolymers via living ROMP, of two different norbornene derivatives (each of which polymerizes to essential completion); where desired, this gradient can be minimized by limiting the monomer conversion . Most of the prior C–N copolymerizations were conducted with heterogeneous catalysts well‐known to be nonliving, while some employed molecular Ru‐centered (Grubbs‐type) initiators that are known to be living under certain conditions . However, the high molecular weight dispersity ( Ð ≈2) and the disconnect between the measured values of the number‐average molecular weight and the monomer‐to‐initiator ratio indicate that these polymerizations did not conform to the ideal living case required to generate a gradient copolymer with little interchain heterogeneity.…”

Statistical copolymers of N‐vinylpyrrolidone and 2‐(dimethylamino)ethyl methacrylate via RAFT: Monomer reactivity ratios, thermal properties, and kinetics of thermal decomposition

“…It is well known that copolymer properties are correlated to copolymer structure, so, the elucidation and manipulation of structure (composition, monomer sequence distribution) and kinetics (propagation rate coefficients and reactivity ratios) are of major importance. An enormous amount of work, both experimental and theoretical, describes the significance of copolymerization in the field of polymer science …”

“…An enormous amount of work, both experimental and theoretical, describes the significance of copolymerization in the field of polymer science. [3][4][5][6][7][8][9][10][11][12] This study is focused on the Reversible Addition-Fragmentation chain Transfer (RAFT) copolymerization of N-vinylpyrrolidone (NVP) and 2-(dimethylamino)ethyl methacrylate (DMAEMA). RAFT is a powerful and broadly applicable method for copolymerization as it combines the benefits of conventional radical polymerization and that of living polymerization techniques.…”