title: Exploration of polyamide structure-property relationships by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.
abstract: BACKGROUND
  Polyamides (PA) are among the most used classes of polymers because of their attractive properties. Depending on the nature and proportion of the co-monomers used for their synthesis, they can exhibit a very large range of melting temperatures (Tm ). This study aims at the correlation of data from mass spectrometry (MS) with differential scanning calorimetry (DSC) and X-ray diffraction analyses to relate molecular structure to physical properties such as melting temperature, enthalpy change and crystallinity rate.
  
  
  METHODS
  Six different PA copolymers with molecular weights around 3500 g mol(-1) were synthesized with varying proportions of different co-monomers (amino-acid AB/di-amine AA/di-acid BB). Their melting temperature, enthalpy change and crystallinity rate were measured by DSC and X-ray diffraction. Their structural characterization was carried out by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Because of the poor solubility of PA, a solvent-free sample preparation strategy was used with 2,5-dihydroxybenzoic acid (2,5-DHB) as the matrix and sodium iodide as the cationizing agent.
  
  
  RESULTS
  The different proportions of the repeating unit types led to the formation of PA with melting temperatures ranging from 115°C to 185°C. The structural characterization of these samples by MALDI-TOF-MS revealed a collection of different ion distributions with different sequences of repeating units (AA, BB; AB/AA, BB and AB) in different proportions according to the mixture of monomers used in the synthesis. The relative intensities of these ion distributions were related to sample complexity and structure. They were correlated to DSC and X-ray results, to explain the observed physical properties.
  
  
  CONCLUSIONS
  The structural information obtained by MALDI-TOF-MS provided a better understanding of the variation of the PA melting temperature and established a structure-properties relationship. This work will allow future PA designs to be monitored.
authors: Normandie Université, COBRA, UMR 6014 and FR3038, Université de Rouen; INSA de Rouen; CNRS, IRCOF, 1 rue Tesnière, 76821, Mont-Saint-Aignan Cedex, France.
authors: Caroline
authors: C
authors: Barrère
authors: Majed
authors: M
authors: Rejaibi
authors: Aurélien
authors: A
authors: Curat
authors: Marie
authors: M
authors: Hubert-Roux
authors: Hélène
authors: H
authors: Lavanant
authors: Carlos
authors: C
authors: Afonso
authors: Nasreddine
authors: N
authors: Kebir
authors: Nicolas
authors: N
authors: Desilles
authors: Laurence
authors: L
authors: Lecamp
authors: Fabrice
authors: F
authors: Burel
authors: Corinne
authors: C
authors: Loutelier-Bourhis
mesh_terms: D002152:Calorimetry, Differential Scanning; D003460:Crystallization; D008968:Molecular Conformation; D009757:Nylons / Q000032:analysis / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013223:Statistics as Topic; D013329:Structure-Activity Relationship; D044366:Transition Temperature; D014961:X-Ray Diffraction
chemical_list: D009757:Nylons