Characterisation of UV-cured acrylate networks by means of hydrolysis followed by aqueous size-exclusion combined with reversed-phase chromatography.
UV-cured networks prepared from mixtures of di-functional (polyethylene-glycol di-acrylate) and mono-functional (2-ethylhexyl acrylate) acrylates were analysed after hydrolysis, by aqueous size-exclusion chromatography coupled to on-line reversed-phase liquid-chromatography. The mean network density and the fraction of dangling chain ends of these networks were varied by changing the concentration of mono-functional acrylate. The amount and the molar-mass distribution of the polyethylene-glycol chains between cross-links (M(XL)) and polyacrylic acid (PAA) backbone chains (the so-called kinetic chain length (kcl)) in the different acrylate networks were determined quantitatively. The molar-mass distribution of kcl revealed an almost linear dependence on the concentration of mono-functional acrylate. Analysis of the starting materials showed a significant concentration of mono-functional polyethylene-glycol acrylate. In combination with the analysis of the extractables of the UV-cured networks (polymers not attached to the network, impurities that originate from the photo-initiator and unreacted monomers), more insight in the total network structure was obtained. It was shown that the UV-cured networks contain only small fractions of residual compounds. With these results, the chemical network structure for the different UV-cured acrylate polymers was expressed in network parameters such as the number of PAA units which are cross-linked, the degree of cross-linking, and the network density, which is the molar concentration of effective network chains between cross-links per volume of the polymers. The mean molar mass of chains between chemical network junctions (M(C)) was calculated and compared with results obtained from solid-state NMR and DMA. The mean molar mass of chains between network junctions as determined by these methods was similar.
Peters
R
R
DSM Research, P.O. Box 18, 6160 MD Geleen, The Netherlands. Ron.Peters@DSM.com
Litvinov
V M
VM
Steeman
P
P
Dias
A A
AA
Mengerink
Y
Y
van Benthem
R
R
de Koster
C G
CG
van der Wal
Sj
S
Schoenmakers
P
P
D000179:Acrylates / Q000737:chemistry / Q000528:radiation effects; D002850:Chromatography, Gel / Q000379:methods*; D002853:Chromatography, Liquid / Q000379:methods; D006868:Hydrolysis; D011092:Polyethylene Glycols / Q000737:chemistry / Q000528:radiation effects*; D014466:Ultraviolet Rays
D000179:Acrylates; C437167:poly(ethylene glycol)diacrylate; D011092:Polyethylene Glycols; C036758:2-ethylhexyl acrylate