Vapor‐phase graft copolymerization of binary solid monomers onto poly(ethylene‐co‐vinyl acetate) film by ultraviolet irradiation

Abstract

Vapor‐phase graft copolymerizations of acenaphthylene–maleimide or acenaphthylene–maleic anhydride binary solid monomers onto poly(ethylene‐co‐vinyl acetate) films were carried out under ultraviolet irradiation. The extent of sorption of single or binary monomers increased with the increasing vinyl acetate content in the backbone polymers. The sorbed binary monomers were mainly composed of acenaphthylene, but the maleimide or maleic anhydride fraction increased with the increasing vinyl acetate content of the films and the composition was little affected by surface hydrolysis. In all series of graft polymerization of single or binary monomers the overall extent of grafting increased with the vinyl acetate content and was suppressed by the surface hydrolysis of the backbone film. The composition of the grafted copolymer, however, differed markedly, depending on the combination of binary monomers. The grafted copolymer in the acenaphthylene–maleimide system was composed mainly of acenaphthylene units, whereas that in the acenaphthylene–maleic anhydride system was composed mainly of maleic anhydride units. The results were compared with those of γ‐ray grafting, and it was suggested that the contribution of a direct supply of monomers from vapor phase and the existence of an acetoxy group on the surface of the film should play an important role in the grafting reaction.

Self‐initiating performance of maleic anhydride on surface photografting polymerization

“…For a long time, however, MAH has been regarded as a monomer with low polymerizability because of steric hindrance caused by disubstitution,1 and copolymerization via a charge‐transfer complex is still the main method of obtaining expected polymers 2, 3. This is also true in the field of photografting polymerization, where MAH is grafted onto substrates in the form of binary monomer systems 4, 5. In our recent studies on surface‐photografting modification, MAH was successfully photografted onto low‐density polyethylene (LDPE) substrates to a considerable extent and at a fair rate 6, 7.…”

Surface photografting polymerization of vinyl acetate, maleic anhydride, and their charge‐transfer complex. V. Charge‐transfer complex (1)

“…[13][14][15] That is, the substrate and MAH and another monomer were placed in a reactor: with heating, the reactor was filled with monomers by vaporization, and some monomer precipitated on the substrate, and with UV-light irradiation, photografting polymerization was started. According to these studies, adding MAH definitely facilitated the photografting polymerization of some monomers, such as styrene and vinyl ethers, but for other monomers, this effect was not obvious.…”

Solvent-Free Vapor-Phase Photografting of Acrylamide onto Poly(ethylene terephthalate)

“…Other alternatives are surface graftings initiated by UV-, UV-laser-, γ-, or electron beam (EB) irradiation, which are also carried out in heterogeneous systems where the substrate could be exposed to monomer in a surrounding liquid − or vapor phase. − UV irradiation, especially when provided by a conventional low-powered UV source as in the present work, has a much lower energy compared to the other types of irradiation mentioned above and thus in general the lowest potential to damage the substrate. For materials that are transparent to the UV irradiation, inner as well as outer surfaces could be treated.…”

“…Usually graft initiation by UV, known as photografting, is accomplished in the presence of a co-initiator, which upon UV-irradiation will generate radicals by internal bond scission or hydrogen abstraction from the substrate surface. , Early studies carried out on photografting in pure reagent vapor used 1 or 2 days of sorption of monomer or co-initiator into the substrate prior to UV-irradiation with cycle times also on the order of days using a high-pressure mercury lamp. − Under such conditions graft yields on the order of mg/cm 2 could be obtained, but both processing conditions and yields seem incompatible with surface patterns in the submicron range.…”

“…34,35 Early studies carried out on photografting in pure reagent vapor used 1 or 2 days of sorption of monomer or co-initiator into the substrate prior to UV-irradiation with cycle times also on the order of days using a high-pressure mercury lamp. [25][26][27] Under such conditions graft yields on the order of mg/cm 2 could be obtained, but both processing conditions and yields seem incompatible with surface patterns in the submicron range.…”