Details

Autor(en) / Beteiligte

• Adamu, Bashir

Titel

Catalytic chain transfer polymerization of methacrylates and styrene

Ort / Verlag

ProQuest Dissertations & Theses

Erscheinungsjahr

1999

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• Low molecular weight poly(acrylates and methacrylates) are extensively used as macromonomers in the syntheses of block and graft copolymers, and in the formulation of "high solids" paints and coatings. Molecular weight control is commonly achieved by using thiols. However, thiols impart undesirable properties such as color, odor and toxicity to the finished products. More recently, the use of cobalt (II) oximes has proved to be efficient in achieving molecular weight control This new class of compounds works at parts per million levels. It also eliminates the problems encountered with conventional molecular weight regulators. This study involved the synthesis and characterization of cobalt alphafurildioxime $\rm\{Co(\alpha$-fdo-2H)$\rm\sb{2}(BF\sb{2})\sb{2}{\cdot}2H\sb{2}O\}$, and its use as a potential catalytic chain transfer agent (CCTA) in the bulk free radical homo- and co-polymerization of some methacrylates and styrene monomers. Azobis(isobutyronitile), AIBN was used as initiator. Elemental analysis and UV-visible technique were used to characterize the CCTA. Molecular weight of the resulting polymers was studied by dilute solution viscometry (DSV) and gel permeation chromatography (GPC). Catalytic chain transfer constant (C$\sb{\rm S}$) values were evaluated using the Mayo equation. The effects of the chain transfer agent on polydispersity index (PDI) and monomer conversion were also investigated. Molecular weights obtained from both DSV and GPC and were found to decrease with increasing concentration of the CCTA. C$\sb{\rm S}$ values evaluated were comparable in magnitude to those reported in the literature. The samples had a relatively narrow polydispersity in the range of 1.5 to 2.0. Monomer conversion was found to decrease with increasing concentration of the CCTA. This has been attributed to retardation in rate of certain processes.