5873-93-8Relevant articles and documents
Controlled free radical polymerization in water-borne dispersion using reversible addition-fragmentation chain transfer
Vosloo,De Wet-Roos,Tonge,Sanderson
, p. 4894 - 4902 (2002)
A novel approach to conducting controlled free radical polymerization in water-borne organic dispersions using reversible addition-fragmentation chain transfer (RAFT) has been studied. The novel approach in this study focused on eliminating monomer and oligomer transport and comprised two fundamental steps: the synthesis of dithiobenzoate-end-capped styrene oligomers in bulk followed by emulsification of these oligomers to yield a polymerizable water-borne dispersion. Dithioesters that act as chain transfer agents in the RAFT process were synthesized in situ. The free radical polymerization of the dithiobenzoate-end-capped styrene oligomers in the water-borne organic dispersion proceeded in a controlled manner: molar mass increased in a linear fashion with increasing conversion, while polydispersities remained low. The familiar red layer formation associated with RAFT polymerization in conventional emulsions was not observed under these conditions. The effects of changing the costabilizer (hydrophobe) and the degree of polymerization of the emulsified oligomers were investigated. Better control was achieved with a less hydrophilic costabilizer and for the shorter of the oligomers tested.
Ubiquitous Nature of Rate Retardation in Reversible Addition-Fragmentation Chain Transfer Polymerization
Bradford, Kate G. E.,Petit, Leilah M.,Whitfield, Richard,Anastasaki, Athina,Barner-Kowollik, Christopher,Konkolewicz, Dominik
, p. 17769 - 17777 (2021/11/10)
Reversible addition-fragmentation chain transfer (RAFT) polymerization is one of the most powerful reversible deactivation radical polymerization (RDRP) processes. Rate retardation is prevalent in RAFT and occurs when polymerization rates deviate from ideal conventional radical polymerization kinetics. Herein, we explore beyond what was initially thought to be the culprit of rate retardation: dithiobenzoate chain transfer agents (CTA) with more active monomers (MAMs). Remarkably, polymerizations showed that rate retardation occurs in systems encompassing the use of trithiocarbonates and xanthates CTAs with varying monomeric activities. Both the simple slow fragmentation and intermediate radical termination models show that retardation of all these systems can be described by using a single relationship for a variety of monomer reactivity and CTAs, suggesting rate retardation is a universal phenomenon of varying severity, independent of CTA composition and monomeric activity level.
Tert-amyl methyl ether preparation method and light gasoline modification method
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Paragraph 0088, (2018/06/14)
The invention discloses a tert-amyl methyl ether preparation method and a light gasoline modification method. The tert-amyl methyl ether preparation method comprises that methanol and isopentene contact an etherification catalyst under an etherification reaction condition to obtain the reaction product containing tert-amyl methyl ether, wherein the etherification catalyst is a polymer supported ionic liquid catalyst, and has a structure represented by a formula (I) or a formula (II). With the method of the present inventin, the tert-amyl methyl ether preparation reaction can maintain the highreactivity.