𝔖 Bobbio Scriptorium
✦   LIBER   ✦

Thiols as chain transfer agents in free radical polymerization in aqueous solution

✍ Scribed by C. Henrı́quez; C. Bueno; E.A. Lissi; M.V. Encinas

Publisher
Elsevier Science
Year
2003
Tongue
English
Weight
99 KB
Volume
44
Category
Article
ISSN
0032-3861

No coin nor oath required. For personal study only.

✦ Synopsis

The behavior of thiophenol and aliphatic thiols of different structure as chain transfer agents in the polymerization of acrylamide and 1vinyl-2-pyrrolidone in aqueous solution at 25 8C was studied. Addition of millimolar concentrations of thiols to acrylamide polymerization reduced notably the polymer molecular weights, without change of the polymerization rate. Measurements at different pH showed that the reactive species towards the macroradicals is the protonated -SH group. Chain transfer constants, determined from Mayo plots, are only slightly dependent on the thiol structure. Aliphatic thiols and thiophenol react at similar rates. The selectivity is opposite for acrylamide (electron acceptor) and 1-vinyl-2-pyrrolidone (electron donor), pointing to significant charge transfer contributions. The reactions rates of these sulfur compounds with the electrophilic DPPH z radical showed higher selectivity, and are not related with the chain transfer constants measured for the acrylamide macroradicals. These results are explained in terms of the different factors that control the reactivity of thiols with macroradicals.

📜 SIMILAR VOLUMES

Online Monitoring of Chain Transfer in F
Online Monitoring of Chain Transfer in Free-Radical Polymerization
✍ Bruno Grassl; Alina M. Alb; Wayne F. Reed 📂 Article 📅 2001 🏛 John Wiley and Sons 🌐 English ⚖ 158 KB 👁 2 views

## M - w vs conversion for several experiments. Also shown are linear fits to the asymptotically linear portion described by the QSSA.

Thiourea as a transfer agent in the radi
Thiourea as a transfer agent in the radical polymerization of methyl methacrylate in aqueous solution at 42
✍ D. Pramanick; A.K. Chatterjee 📂 Article 📅 1980 🏛 Elsevier Science 🌐 English ⚖ 313 KB

Chain transfer involving thiourea in radical polymerization of methyl methacrylate in acidic aqueous media has been studied by polymer endgroup analysis using the dye-partition technique. Thiourea has feeble reactivity in chain transfer, the transfer constant with respect to poly (methyl methacrylat

Iodoform as a transfer agent in radical
Iodoform as a transfer agent in radical polymerizations
✍ C.A. Barson; J.C. Bevington; B.J. Hunt 📂 Article 📅 1996 🏛 Elsevier Science 🌐 English ⚖ 477 KB

Iodoform has been examined as a reactive transfer agent in the radical polymerizations at 60°C of styrene and methyl methacrylate using azobisisobutyronitrile as initiator. The transfer constants have been determined by a procedure depending upon the determination of the initiator fragments incorpor