Functionality Dependent Olefin Activity in Acyclic Diene Metathesis Polymerization:  Mass Spectrometry Characterization of Amino Acid Functionalized Olefins

Abstract

Mass spectrometry has become an essential tool in delineating the structural properties of a new series of amino acid functionalized acyclic diene metathesis (ADMET) polymers known as bioolefins. These measurements, coupled with the measurement of the polymers chemical and physical properties, assist in the determination of their utility as biomaterials. In the present study, a set of five polymers with different bulk size and electronic properties were chosen for structural analyses by MALDI-TOF, MALDI-FTICR, and DIOS-TOF. The obtained data show that due to the competing metathesis and isomerization during ADMET, depending on their structural properties, the olefins display different selectivity toward main metathesis or isomerized products.

Studying and Suppressing Olefin Isomerization Side Reactions During ADMET Polymerizations

“…For instance, MALDI‐TOF MS and NMR have been used to study olefin isomerization side reactions during ADMET polymerizations. Unfortunately, only oligomers can be investigated in the case of MALDI and NMR investigations are only possible due to the presence of different chemical shifts of isomerized and non‐isomerized structures, which is not the case for all ADMET derived polymers 20–22. Moreover, model studies with 1‐octene revealed that the second generation Grubbs catalyst produces a significant amount of olefin isomerization at temperatures of 50–60 °C and that the extent of isomerization can be reduced by lowering the reaction temperature 18.…”

Ethylene–ethyl acrylate copolymers via ADMET polymerization: Effect of sequence distribution on thermal properties

“…A family of peaks with a regular interval that equals to the theoretical mass of the repeating unit was observed in each of these spectra, indicating the integrity of the periodic microstructure. More importantly, minor series of peaks deviating from the major series by several methylene units due to olefin isomerization were not detected, confirming the excellent capability of Grubbs‐I catalyst in preventing olefin isomerization …”

“…Unfortunately, moderate molecular weight products were generated due to the decreased monomer concentration (data not shown). Importantly, to prevent olefin isomerization, Grubbs‐I catalyst was selected for ADMET polymerization in this study . The unsaturated periodic copolymers are designated as P1–P3 , whereas the unsaturated random copolymers are designated as P1a–P3c (see Scheme ), respectively.…”

Precision polymers containing main-chain-amino acids: ADMET polymerization and crystallization

“…Due to different activity and isomerization rates [46][47][48][49] Grubbs Catalyst rst generation (Grubbs 1 st ), second generation (Grubbs 2 nd ) and Hoveyda-Grubbs Catalyst rst generation (GH 1 st ) were tested for the chosen reaction conditions. In Table 2 the results of the molecular weights (obtained by NMR and GPC as well as the PDI's), the yields and the obtained trans : cis ratio of the internal double bonds for the different catalyst are displayed.…”