Photopolymerization without Photoinitiator of Bismaleimide‐Containing Oligo(oxypropylene)s: Effect of Oligoethers Chain Length

Abstract

This article describes the synthesis and characterization of a series of poly(propylene glycol bismaleimide) (PPGM) with molecular weights ($\overline M _{{\rm ws}}$) in the range of 390–2 600 g · mol−1. Their photopolymerization rates without photoiniator were similar to that of an acrylate resin in the presence of a photoinitiator. The reactivities and degrees of conversion of these PPGM oligomers, thermal and mechanical properties of the resulting materials were studied as a function of $\overline M _{\rm w}$. Rigid materials were obtained except for that containing the longest PPGM, which exhibited mechanical properties of a rubber. The glass transition temperature values and the thermal stability were found to decrease when $\overline M _{\rm w}$ of used oligomers was increased. Crosslinking density was the parameter that controlled both mechanical and thermal properties.

Photoinitiator‐Free, Open‐Air Acceptor/Donor Copolymerization of Bismaleimides: Simple Polymerization Conditions for New Thermoplastic Elastomer Production

“…Table 3 sums up the initial slopes for the different tested copolymerizations and homopolymerizations to compare their reactivities. Copolymerizations are faster than the homopolymerizations of PPG DP n M oligomers (see polymerization profiles under the same conditions discussued by Pozos Vázquez et al14). Indeed, the reactivity of PPG 4 M/DVE‐3 is six times higher than for PPG 4 M alone, and the one for PPG 7 M/DVE‐3 and PPG 39 M/DVE‐3 is 3 times higher than for PPG 7 M and PPG 39 M, respectively.…”

“…The bismaleimide synthesis was carried out in two steps, according to previously described synthetic pathway:14, 15 first, the addition of the maleic anhydride to the diamine precursors, which generates the intermediate bismaleamic acid, and second, the subsequent cyclodehydration in the presence of the dehydrating system ZnBr 2 /HMDZ to give the bismaleimide without side‐producing the corresponding isomaleimide. To elaborate bismaleimide/divinyl ether copolymers with various photo‐crosslinking ratios, three different PPG DP n M bismaleimide oligomers with DP n increasing from 4 to 39 have been synthesized (Table 1).…”

“…Three poly(propylene glycol) bis (2‐maleimidepropyl ether)s with number average molecular weights ( M n ) of 390, 580, and 2570 g mol −1 were synthesized as described in a previous paper 14. Respective poly(propylene glycol) bis(2‐aminopropyl ether)s (purchased from Aldrich) precursors were reacted with maleic anhydride.…”

“…Recently, we have reported on the elaboration of polymeric films obtained from UV‐cured poly(propyleneglycol) and poly(dimethylsiloxane) bearing maleimides end groups 14, 15. The cross‐linking density for both types of homopolymers was successfully controlled by varying the length chain between reactive groups.…”

Discoloration mechanism of UV-curable polymer/metal hybrid coating

“…However, the photoinitiators are not completely consumed in the polymerization process since it is common practice to use an excess of photoinitiators to attain a fast curing system, as demanded by the coating ink industry. Hence, the compounds are often trapped into the polymeric network and can cause yellowing especially if they are composed of aromatic or chromophoric functional groups since they may absorb light in the visible light region [27,28].…”