Chain transfer of vegetable oil macromonomers in acrylic solution copolymerization

Abstract

The use of vegetable oil macromonomers (VOMMs) as comonomers in emulsion polymerization enables good film coalescence without the use of solvents that constitute volatile organic compounds (VOCs). VOMMs are derived from renewable resources and offer the potential of post-application crosslinking via auto-oxidation. However, chain transfer reactions of VOMMs with initiator and/or polymer radicals during emulsion polymerization reduce the amount of allylic hydrogen atoms available for primary auto-oxidation during drying. Vegetable oils and derivatives were reacted with butyl acrylate and methyl methacrylate via solution polymerization, and the polymerization was monitored using in situ infrared spectroscopy to determine the extent of chain transfer.1 H NMR spectroscopy was used to determine the loci of chain transfer and the molecular weight characteristics of the polymers were characterized by SEC. Solution polymerization was utilized because this limited temperature fluctuations and insolubility of the polymer.

Vegetable Oils Acting as Encapsulated Bioactives and Costabilizers in Miniemulsion Polymerization Reactions

“…This increase in Tg may have happened due to the auto‐oxidation of the allylic unsaturation belonging to the vegetable oils caused by the storage conditions, in which the samples were stocked in a 100 mL glass amber with black sealing cap in a drawer at room temperature. This same observation was made by Black; Messman; Rawlins, who studied the chain transfer of vegetable oil macromonomers in acrylic solution copolymerization.…”

“…The thermograms (second heating) from differential scanning calorimetry for each polymer are presented in Figure 5. The endothermic peak appearing for hexadecane at [41] who studied the chain transfer of vegetable oil macromonomers in acrylic solution copolymerization. STEM images suggest the grafting of argan oil in the polymer as can be seen in Figure 6.…”

Encapsulation of Vegetable Oils by Miniemulsion Polymerization: Mathematical Modeling

“…In this sense, chain transfer reactions are expected to occur more for linseed oil. Black et al (2011) showed similar results for MMA/BA solution polymerization reactions using 33 wt% of soybean oil, linseed oil or tung oil. According to these authors, chain transfer greatly retarded the polymerization rate in reactions conducted in the presence of vegetable oils, with the effect increasing in order of soybean oil, linseed oil and tung oil (which contains about 70 % of a fatty acid with three conjugated double bonds).…”

“…Thus, the highest molecular weights were obtained in the reaction with hexadecane and the lowest ones were obtained in reactions with linseed oil, as shown in Table 4. This effect on the molecular weight was also observed by Black et al (2011), especially when oils with conjugated double bonds were used.…”

“…Additionally, higher degrees of unsaturation support greater electron delocalization and increase the resonance stability of the radicals, thereby promoting chain transfer reactions. The activation energy for free radical formation is lower in linoleic and linolenic acid than in oleic acid because of the active methylene group situated between the double bonds that leads to enhanced allylic radical stability (Black et al, 2011). Linseed oil has about 43 % of linolenic acid, 18 % of linoleic acid and 23 % of oleic acid, which contain respectively three, two and one double bond.…”