A Nitroxide for Effecting Controlled Nitroxide-Mediated Radical Polymerization at Temperatures ≤90 °C

Abstract

Factors underlying design of a new nitroxide, 2,2,5trimethyl-4-tert-butyl-3-azahexane-3-oxyl (TITNO), and its styrene alkoxyamine (Styryl-TITNO) for effecting nitroxide-mediated polymerization (NMP) at temperatures ≤90 °C are described. The rate coefficient, k d , for thermal dissociation of Styryl-TITNO was determined in the range 70−100 °C, giving Arrhenius parameters A d = 2.9 × 10 12 s −1 and E d = 104.1 kJ mol −1 . Due to the low value of E d , values of k d and the activation−deactivation equilibrium constant for NMP of n-butyl acrylate (BA) and styrene are much lower at any given temperature than for alkoxyamines of more established nitroxides. Good control of molecular weight and dispersity, with negligible contributions from termination, is achieved at 90 °C for BA and at 70 °C for styrene, thus, eliminating the complicating contributions from styrene thermal initiation. Hence, TITNO and Styryl-TITNO offer new opportunities for controlled NMP at temperatures much lower than has previously been attainable.

Redox Active Compounds in Controlled Radical Polymerization and Dye‐Sensitized Solar Cells: Mutual Solutions to Disparate Problems

“…[87][88][89][90] For example, while TEMPO is only capable of polymerization at significant rate at temperatures of 125-135 8Ct he bulkiera cyclic nitroxides, TIPNO and SG1, are capable of polymerizationa tl ess than 120 8Cd ue to ac ombination of the increase in steric bulk as well as due to electronic considerations. [87,88] With respectt oD SSCs, far less work has been conducted, but Gryn'ova et al have studied the structure-activity relationship for as eries of cyclic nitroxides as redox mediators in DSSCs and observed ab road spectrumo fn itroxides that may be suitable. [87,88] With respectt oD SSCs, far less work has been conducted, but Gryn'ova et al have studied the structure-activity relationship for as eries of cyclic nitroxides as redox mediators in DSSCs and observed ab road spectrumo fn itroxides that may be suitable.…”

“…[86] It has already been commented that steric bulk plays an important role in determining the rate of recombination in DSSCs and as imilare ffect can be observed in CRP using nitroxides with respect to recombination of the nitroxide with the alkyl radicals pecies. [87][88][89][90] For example, while TEMPO is only capable of polymerization at significant rate at temperatures of 125-135 8Ct he bulkiera cyclic nitroxides, TIPNO and SG1, are capable of polymerizationa tl ess than 120 8Cd ue to ac ombination of the increase in steric bulk as well as due to electronic considerations. [87][88][89][90] For example, while TEMPO is only capable of polymerization at significant rate at temperatures of 125-135 8Ct he bulkiera cyclic nitroxides, TIPNO and SG1, are capable of polymerizationa tl ess than 120 8Cd ue to ac ombination of the increase in steric bulk as well as due to electronic considerations.…”

ChemInform Abstract: Redox Active Compounds in Controlled Radical Polymerization and Dye‐Sensitized Solar Cells: Mutual Solutions to Disparate Problems

“…In this respect, significant progress has been made in nitroxide-mediated polymerization in recent years with the advent of various bulky cyclic and acyclic nitroxides ( Figure 7) that have made low temperature polymerizations possible. [87][88][89][90] For example, while TEMPO is only capable of polymerization at significant rate at temperatures of 125-135 8Ct he bulkiera cyclic nitroxides, TIPNO and SG1, are capable of polymerizationa tl ess than 120 8Cd ue to ac ombination of the increase in steric bulk as well as due to electronic considerations. [89,90] The recently developed nitroxides TITNO and nitroxide-1 (see Figure 7f or structures) have extended this work due to the increasei nt he steric bulk around the nitro- Chem.…”

Ru(bpy)32+ derivatized polystyrenes constructed by nitroxide-mediated radical polymerization. Relationship between polymer chain length, structure and photophysical properties

“…Macromolecular structures for PS 14 -Ru and PS 20 -Ru polymers were obtained from fully-atomistic molecular dynamics simulations in two explicit solvents (acetonitrile, ACN and methanol, MeOH) along with their corresponding counter ions (PF 6 − and Cl − , respectively). The atomic charges for the monomer units were obtained from Gaussian09 7 calculations with the B3LYP functional and LANL2DZ basis set.…”

“…The atomic charges for the monomer units were obtained from Gaussian09 7 calculations with the B3LYP functional and LANL2DZ basis set. 5 compares the radial distribution function (g(r)) for PS 14 -Ru and PS 20 -Ru in ACN and MeOH, where the position of the first peak represents the closest center-to-center Ru-Ru distance within each polymer. Dynamics were calculated for a total of 1 ns in each polymer system and snapshots were collected every 2.5 ps, giving a trajectory with 400 snapshots for analysis.…”