RESUMEN
Continuous research into polyhydroxyalkanoates (PHAs), biodegradable polymers which can be produced by, and harvested from, various bacteria has led to more cost-effective ways of isolating and commercializing them. As bio-based polymers, PHAs can be transformed into compostable bioplastics and utilized for a variety of applications. Often isolated as copolymers, the monomeric ratio compositions of these products greatly affect both the properties and consequently, possible end uses of these products. As such, methods of reliably characterizing these ratios are important for quality control and product development purposes. Herein, we discuss how 1H benchtop nuclear magnetic resonance (NMR) instruments can be used for the determination of monomeric ratio compositions in PHAs and compare results obtained at three different NMR field strengths: 1.40 T (60 MHz), 2.35 T (100 MHz), and 9.4 T (400 MHz).
RESUMEN
Biobased farnesene (Far) was polymerized by nitroxide-mediated polymerization in miniemulsions using two different alkoxyamine initiators, the SG1-based and succinimidyl-modified BlocBuilder (NHS-BB) and Dispolreg 007 (D7). Stable emulsions were observed after 30 h of reaction at 90 °C, where NHS-BB-initiated systems resulted in smaller particles (â¼300 nm) than using D7 (â¼400 nm). Successful chain extension of the poly(Far) macroinitiators (24,500-39,700 g mol-1) with styrene were achieved using 15 wt % surfactant relative to monomer concentration. Compartmentalization effects were not observed in these emulsions as the polymerization rate was still much slower compared to the bulk, even though Z-averaged particle sizes were around 300-400 nm. Finally, all biobased diblock copolymers were synthesized by chain-extending poly(Far) macroinitiators with isobornyl methacrylate (iBOMA), where the D7 initiator showed more effective chain extension (less unreacted macroinitiator) than NHS-BB.