Synthesis of Macromonomers via Catalytic Chain Transfer (CCT) Polymerization and their Characterization via NMR Spectroscopy and Electrospray Ionization Mass Spectrometry (ESI‐MS)

Abstract

Summary: Macromonomers consisting of a butyl acrylate (BA) tail and α‐methyl styrene (AMS) or benzyl methacrylate (BzMA) unsaturated termini were synthesized via catalytic chain transfer (CCT) polymerization employing the low spin bis(difluoroboryl)dimethylglyoximato cobalt (II) (COBF) complex. The structures of the generated macromonomers were characterized via 1H and 13C NMR spectroscopy and electrospray ionization mass spectrometry (ESI‐MS). A variety of low molecular weight ($\overline M _{\rm n}$ < 4 000 g · mol−1) BA/AMS and BA/BzMA macromonomers were generated by varying the reaction conditions. The generated BA/AMS macromonomers are shown to be terminated by an AMS moiety while consisting of n units of BA plus 1 to 3 units of AMS. The structures of the synthesized BA/BzMA macromonomers give a more complex mixture. Apart from BzMA terminated macromonomer chains consisting of n units of BA plus 1 to 3 units of BzMA, pure BA macromonomers were also generated.Possible structure of BA/AMS macromonomers with various length of the BA tail and a different number of AMS units.magnified imagePossible structure of BA/AMS macromonomers with various length of the BA tail and a different number of AMS units.

Polyolefin–Polar Block Copolymers from Versatile New Macromonomers

“…This led to AMS being incorporated selectively as an end group because the tertiary benzylic AMS radical so formed does not propagate at a significant rate. 50 If our AMS-like macromonomers PE-i-DIB [ Figure 4(a)] and EH-i-DIB were also incorporated terminally in such a reaction, block copolymers of the much sought-after kind described in the introduction would be produced viz. In preliminary experiments we attempted copolymerizations of PE-i-DIB with excess n-BA in toluene at high temperature (125°C) as recommended, 50 using 2,2'-azobis(2methylpropionitrile) (AIBN) as the initiator and COBF as the chain transfer catalyst.…”

The role of mid‐chain radicals in acrylate free radical polymerization: Branching and scission

“…At that time, the resulting polymer was analyzed via SEC and NMR and the terminal double bond was unambiguously assigned to carry two geminal hydrogen atoms rather than vicinal atoms (as would be found in the macromonomer product made via catalytic chain transfer polymerization). 45,95 However, only recently the full mechanism of the macromonomer formation was resolved via high-resolution mass spectrometry on the product from autoinitiated polymerization at 140 C in 5% butyl acetate solution. 48,96 Instead of a simple consecution of transfer and scission of the formed MCR, relatively complex equilibria are in place that promote macromonomer formation.…”

Organization and metamorphosis of glia in the Drosophila visual system

“…The general ability to obtain macromonomers from simply heating an acrylate/solvent mixture to high temperatures in the presence of very low amounts of radical initiators was already realized by Chiefari et al45 almost 10 years ago. At that time, the resulting polymer was analyzed via SEC and NMR and the terminal double bond was unambiguously assigned to carry two geminal hydrogen atoms rather than vicinal atoms (as would be found in the macromonomer product made via catalytic chain transfer polymerization) 45, 95…”