Is it possible to extend the coleman-fox method for polymer sequence determination by NMR to copolycondensates?

A new theory is presented for the interpretation of NMR spectra of copolycondensates, with special attention to those obtained by melt mixing of two macromolecular chains (reactive blending). The repeat unit is split into two parts, referred to as half-monomers. The present theory gives a highly accurate description of the changes in the sequence distribution during the reactive blending reaction, since the effect of the first and second neighbors along the macromolecular backbone (half-monomer penultimate effect) is explicitly considered.

Analysis of melt copolymers.

Melt copolymer chains are the main (most abundant) reaction product obtained when heating a blend of two (or more) condensation polymers (such as polyester + polycarbonate or polyester + polyamide or polyester + polyester) in which exchange reactions occur. In fact, during the melt-mixing reaction, an AB copolymer is formed and, as a consequence, the sample is a complex mixture made of three components or simply "parts", referred to as Z1, Z2 and Z3, where Z1 and Z2 are the parts for unreacted homopolymers (A and B), whereas Z3 is the part for the copolymer. In this paper, it is shown that matrix-assisted laser desorption/ionization mass spectrometry (and mass spectrometry in general) can be used to monitor the yield of the reactive blending reaction, YR, by measuring the amount of unreacted homopolymer (Z1 and Z2).

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with size-exclusion chromatographic fractionation for structural characterization of synthetic aliphatic copolyesters.

We report matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) and off-line coupling of size-exclusion chromatography with MALDI-TOFMS analysis (SEC/MALDI-TOFMS) methods for the detailed characterization of poly[(R,S)-3-hydroxybutyrate-co-L-lactic acid], P[(R,S)-3HB-co-LA], and poly[(R,S)-3-hydroxybutyrate-co-epsilon-caprolactone], P[(R,S)-3HB-co-CL], copolymer samples which are expected to be used in special medical application as scaffolds for cartilage and soft tissue engineering. The novel copolyesters contained randomly distributed (R,S)-3-hydroxybutyrate structural units, were synthesized by transesterification of the corresponding homopolymers, i.e.

Molecular architecture of poly[(R,S)-3-hydroxybutyrate-co-6-hydroxyhexanoate] and poly[(R,S)-3-hydroxybutyrate-co-(R,S)-2-hydroxyhexanoate] oligomers investigated by electrospray ionization ion-trap multistage mass spectrometry.

A series of aliphatic copolyesters was obtained from (R,S)-beta-butyrolactone and two isomeric hydroxy acids, 6-hydroxyhexanoic and (R,S)-2-hydroxyhexanoic acids. The reactions were conducted in bulk without catalyst. Electrospray ionization tandem mass spectrometry (ESI-MSn) was used for molecular characterization of these copolyester oligomers.

Mass spectra of copolymers which display compositional drifts or sequence constraints.

The spectral features appearing in mass spectra of random and block copolymers which display a drift in composition are discussed along with features appearing in mass spectra of terpolymers and tetrapolymers with sequence constraints. It is shown that previous models cannot account for these features. A new model is presented and a compact equation is derived which yields MS intensities.

Mass spectra of copolymers.

Recent and older literature (covering the last 12-13 years) in the field of mass spectra of random and block copolymers is reviewed. A detailed description is given of the information on copolymer properties that can be recovered from the analysis of the low-mass region of the spectrum (the region below 500 Da) and the high-mass region. The features of mass spectra of copolymers obtained by different synthetic routes are discussed, such as free radical, condensation, ring-chain equilibration, microbial synthesis, ring-opening, simple anionic, cationic, Ziegler-Natta, and/or metallocene catalysis, along with some random and block copolymers that occur in Nature.