Self‐initiating performance of maleic anhydride on surface photografting polymerization

Abstract

Maleic anhydride (MAH) was photografted onto low-density polyethylene (LDPE) films with a grafting efficiency of about 70% in the absence of a photoinitiator. The self-initiating performance was attributed to a mechanism of abstracting hydrogen atoms from LDPE chains by excited MAH dimers. The supporting experimental results were as follows: (1) the far-UV radiation (200 -300 nm) was indispensable for the graft polymerization and 2) the crosslinking reaction of LDPE inevitably accompanied the grafting of MAH. In addition, the initiation performance of MAH was further confirmed by surface photografting of acrylic acid in the presence of MAH, where MAH was used as the photoinitiator.

Surface Photografting Polymerization of Binary Monomers Maleic Anhydride and n-Butyl Vinyl Ether on Polypropylene Film II. Some Mechanistical Aspects

“…Initiation Performance of MAH MAH, as a monomer, can also act as a photoinitiator under UV irradiation, which has been discovered and reported in our earlier article, 4 and it was further confirmed in this photografting system. First of all, the effect of BP concentration on the photografting was investigated and the results were shown in Figure 4.…”

“…This may offer a possibility for application to carry out the photografting polymerization without photoinitiator. Associating with our previous results 4 that MAH itself could readily undergo photografting in the absence of any photoinitiator and acrylic acid (AA) could perform photografting in the presence of MAH (without adding photoinitiator), the initiation performance of MAH in this photografting system can be naturally deduced.…”

Surface Photografting Polymerization of Binary Monomers Maleic Anhydride and n-Butyl Vinyl Ether on Polypropylene Film I. Effects of Principal Factors

“…19 The results showed that only when the irradiation time was prolonged to 3 min did the grafting efficiency reach 60%. This is because MAH is difficult to homopolymerize under usual conditions due to the great steric hindrance, as commonly considered, which leads to the difficulty of the grafting chain propagation.…”

“…The photografting polymerization was carried out in the apparatus the same as that in the previous pa- pers, 19,23 which was built in our laboratory. The assembly for photografting polymerization is shown schematically in Figure 1, which is named "Film Interface Photopolymerization (FIP)" technique 9 used in our photografting operation.…”

“…In order to make the materials possess special properties, some monomers with functional groups were introduced, 17,18 such as glycidyl acrylate (GA), glycidyl methacrylate (GMA), N-vinyl pyrrolidone (NVP), etc. Maleic anhydride (MAH), however, was seldom used in photografting, 19 although it is widely used in the solution grafting and melting grafting. In fact, MAH used as a monomer for photografting has much advantages: 1) The anhydride group in MAH molecule has comparatively strong polarity and it can be hydrolyzed into two carboxyl groups, which will increase the density of polar groups on the surface of the grafted polymer, and therefore the surface hydrophilicity can be improved effectively.…”