Molar-mass distribution of urea-formaldehyde resins of different degrees of polymerization by MALDI-TOF mass spectrometry

Abstract

This paper describes so me results obtained in an investigati on of urea-formaldehyde (UF) resins of different de grees of poly merisation by matrix-assisted la ser de sorption/ionisation tim e-of-flight (M ALDI-TOF) mass spectrometry (MS). MALDI-TOF MS prove d to be an ap propriate techniq ue for analy zing these ty pes of p olymers, bearin g in mind th at the result s of t he analysis correspond with prev ious phy sical a nd che mical measurements. This technique en ables a relatively swift deter mination of the degree of poly merrisation throug h the monitoring of key changes in the structu re of a poly mer. Thus, in the analysis of UF re sins, it may be possible to monitor a decrea se in the intensity of the monohydroxymethyl urea (MMU) si gnal, which corresponds t o an in crease of the mass spectra v alues i n the mass ra nge of hi gher homologues, above 1000 g mol -1 . A noticeabl e difference concerns the signal intensities in the higher mass ranges (up to 1400 g mol -1 ), which corresponds to more bra nched and longer ho mologues of th e poly mers. Especially , a sign ificantly more intensive signal of MMU wa s registered. The average molecular weight ( MW) of the exa mined sa mples was between 936 and 1324 g m ol -1 , with a maximal deviation of 20 %, depending on the ratios of the reactants.

13C‐NMR, 13C‐13C gCOSY, and ESI‐MS characterization of ether‐bridged condensation products in N,N′‐dimethylurea‐formaldehyde systems

“…Mass spectrometry, and in particular matrix‐assisted laser desorption/ionization‐time‐of‐flight (MALDI‐TOF) mass spectrometry, has been used in the last decade for structure analysis of various resins and polymers 26–29. However, mass spectrometry, gel permeation chromatography/Size exclusion chromatography (GPC/SEC), or elemental analysis do not enable the identification of ether‐bridged condensation products, as these and monomethylolmethylenediurea share the same molecular formula.…”

Evaluation of glycolaldehyde as a formaldehyde substitute in urea-based wood adhesives

“…It is necessary to have a sufficiently high reactivity of unreacted monomers during polymerization, as the concentration of monomers decrease with increasing polymer length. The lower reactivity of GA compared to formaldehyde may be a reason for the observation of shorter oligomers in contrast to MALDI analysis of UF, where masses were observed in the range of 1000 to 5000 Da (Gavrilović-Grmuša et al 2010;Jeong and Park 2019).…”

Reactive toughening of urea–formaldehyde resin with poly(vinyl alcohol) by formation of interpenetrating networks

“…By using different conditions of reaction, preparation of a more or less variety of condensed structures is possible. UF resin can be used as wood glues and surface coatings to improve the wet strength of paper and the crease‐resistance of textiles; powders from UF resins can also be molded and used as containers, electric fittings, bottle caps, lavatory seats, and so on .…”