Atom transfer radical polymerization initiated by N ‐bromosuccinimide

Metal-catalyzed living radical polymerization of methyl methacrylate initiated acid, and N-chloro saccharin) and catalyzed with the self-regulated catalytic system Cu 2 S/2,2 0 -bipyridine is reported. The initiation efficiency of these initiators is determined by their structure. Regardless of the initiator efficiency, in all cases, poly (methyl methacrylate) with narrow molecular weight distribution and functionalized chain-ends was obtained. These new classes of initiators open new strategies for the functionalization of polymer chain-ends and for the synthesis of complex architectures by graft copolymerization initiated from N-chloro proteins, aliphatic, aromatic and semiaromatic polyamides, and polyurethanes. V V C 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5283-5299, 2005

Section: Discussionsupporting

confidence: 73%

N‐chloro amides, lactams, carbamates, and imides. New classes of initiators for the metal‐catalyzed living radical polymerization of methacrylates

Percéc

Grigoraş

2005

“…Various α‐bromo active organic compounds, viz., EB i B, MBP3 (methyl‐2‐bromopropionate) and MBB29 (3‐bromo‐3‐methyl‐2‐butanone), having structural similarities to the of growing polymer chain were used as initiators for ATRP of MMA. Jiang et al has recently utilized NBS as initiator for ATRP of MMA in anisole30 at 90°C. The polymerization resulted in lower polydispersity (1.13) in 2.5 h and 34% conversion, but the initiator efficiency was only 0.17.…”

Section: Resultsmentioning

confidence: 99%

A novel tridentate nitrogen donor as ligand in copper catalyzed ATRP of methyl methacrylate

Mittal

Sivaram

2005

A tridentate ligand, BPIEP: 2,6-bis[1-(2,6-diisopropyl phenylimino) ethyl] pyridine, having central pyridine unit and two peripheral imine coordination sites was effectively employed in controlled/''living'' radical polymerization of MMA at 90 8C in toluene as solvent, Cu I Br as catalyst, and ethyl-2-bromoisobutyrate (EBiB) as initiator resulting in well-defined polymers with polydispersities M w /M n 1.23. The rate of polymerization follows first-order kinetics, k app ¼ 3.4 Â 10 À5 s À1 , indicating the presence of low radical concentration ([P*] 10 À8 ) throughout the reaction. The polymerization rate attains a maximum at a ligand-to-metal ratio of 2:1 in toluene at 90 8C. The solvent concentration (v/v, with respect to monomer) has a significant effect on the polymerization kinetics. The polymerization is faster in polar solvents like, diphenylether, and anisole, as compared to toluene. Increasing the monomer concentration in toluene resulted in a better control of polymerization. The molecular weights (M n,SEC ) increased linearly with conversion and were found to be higher than predicted molecular (M n,Cal ). However, the polydispersity remained narrow, i.e., 1.23. The initiator efficiency at lower monomer concentration approaches a value of 0.7 in 110 min as compared to 0.5 in 330 min at higher monomer concentration. The aging of the copper salt complexed with BPIEP had a beneficial effect and resulted in polymers with narrow polydispersitities and higher conversion. PMMA obtained at room temperature in toluene (33%, v/v) gave PDI of 1.22 (M n ¼ 8500) in 48 h whereas, at 50 8C the PDI is 1.18 (M n ¼ 10,300), which is achieved in 23 h. The plot of ln k app versus 1/T gave an apparent activation energy of polymerization as (DE = app ) 58.29 KJ/mol and enthalpy of equilibrium (DH 0 eq ) to 28.8 KJ/mol. Reverse ATRP of MMA was successfully performed using AIBN in bulk as well as solution. The controlled nature of the polymerization reaction was established through kinetic studies and chain extension experiments. V V C 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: [4996][4997][4998][4999][5000][5001][5002][5003][5004][5005][5006][5007][5008] 2005

“…In ATRP, the function of initiators determines the molecular weight of the polymers and structures of end groups 10–15. Most of the initiators used are organic halides with a potentially active carbon‐halogen bond 1–3, 16–18. However, several thermal‐ and photo‐iniferter reagents were successfully introduced as initiators into the ATRP system by Qiu and coworkers, including 1,1,2,2‐tetraphenyl‐1,2‐ethanediol,19 2,3‐dicyano‐ 2,3‐diphenylsuccinate,20 and 2,3‐dicyano‐2,3‐di (p‐tolyl) succinate 21.…”

Section: Introductionmentioning

confidence: 99%

“Living”/controlled free radical polymerization of MMA in the presence of cobalt(II) 2‐ethylhexanoate: A switch from RAFT to ATRP mechanism

Zhang

Zhu

et al. 2007

A metal complex, cobalt(II) 2‐ethylhexanoate (CEH), was added to the system of thermal‐initiated reversible addition‐fragmentation chain transfer (RAFT) polymerization of methyl methacrylate (MMA) with 2‐cyanoprop‐2‐yl 1‐dithionaphthalate (CPDN) as the RAFT agent at 115 °C. The polymerization rate was remarkably enhanced in the presence of CEH in comparison with that in the absence of CEH, and the increase of the CPDN concentration also accelerated the rate of polymerization. The polymerization in the concurrence of CPDN and CEH demonstrated the characters of “living”/controlled free radical polymerization: the number‐average molecular weights (Mn) increasing linearly with monomer conversion, narrow molecular weight distributions (Mw/Mn) and obtained PMMA end‐capped with the CPDN moieties. Meanwhile, CEH can also accelerate the rate of RAFT polymerization of MMA using the PMMA as macro‐RAFT agent instead of CPDN. Similar polymerization profiles were obtained when copper (I) bromide (CuBr)/N,N,N′,N′′,N′′‐pentamethyldiethylenetriamine was used instead of CEH. Extensive experiments in the presence of butyl methacrylate, bis(cyclopentadienyl) cobalt(II) and cumyl dithionaphthalenoate were also conducted; similar results as those of MMA/CPDN/CEH system were obtained. A transition of the polymerization mechanism, from RAFT process without CEH addition to atom transfer radical polymerization in the presence of CEH, was possibly responsible for polymerization profiles. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5722–5730, 2007