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

Abstract

ABSTRACT:On the basis of the previous work, another experiments were carried out to investigate the photografting polymerization of maleic anhydride (MAH)/ n-butyl vinyl ether (n-BVE) more intensively, from which some particular characteristics related to the mechanism were found out. The activation energy of the overall polymerization (Eap) is about 5.9 kJ mol −1 , while the value of the photografting polymerization (Eag) is around 29.3 kJ mol −1 , which indicates that high reaction temperature would reduce the homopolymerization and accordingly favors the graft polymerization. MAH, as a monomer, could act as a photoinitiator as well, which was deduced from the unexpected phenomenon that the photografting polymerization could perform smoothly even in the absence of photoinitiator. More experiments confirmed that the grafting efficiency reached the highest when the molar ratio of MAH to BVE was 1 : 1, from which it can be concluded that the formation of charge transfer complex (CTC) between MAH and BVE is a crucial factor leading to the high grafting efficiency. The formation of CTC was measured by UV spectra and the equilibrium constant of CTC was determined by 1 H NMR method. As a result, the photografting process of the binary monomers MAH/BVE was outlined.KEY WORDS Surface Photografting Polymerization / Maleic Anhydride / n-Butyl Vinyl Ether / Charge Transfer Complex / In the previous paper, 1 the principal factors affecting the surface photografting polymerization, such as irradiation time, molar ratio of maleic anhydride (MAH) to butyl vinyl ether (BVE), monomer concentration, photoinitiators, ultraviolet (UV) and solvents, have been investigated systematically. On the basis of the above work, a series of another experiments were carried out to investigate the photografting polymerization of MAH/BVE more intensively.In fact, the photografting system with MAH/BVE as binary monomers, benzophenone (BP) as photoinitiator and acetone as solvent is very complicated. First of all, the reaction system is heterogeneous, and the photografting polymerization takes place merely at the liquid-solid interface between the substrate and liquid phase, so the diffusion of monomer and photoinitiator is an important process in the course of the reaction. Besides, the reaction system involves binary monomers MAH and BVE, which tend to form charge transfer complex (CTC). 2 In this paper, we elementarily discovered some aspects related to the mechanism of the photografting of MAH/BVE by investigating the crucial effects of another factors. EXPERIMENTAL MaterialsCommercial casting polypropylene (CPP) film, 30 µm thick, with transmittance close to 100% for the UV radiation, was used as the substrate, which was first cut into circular shape of about 50 mm in diameter and then subjected to Soxhlet extraction with acetone for 24 h to remove the additives and impurities.MAH was purified by distillation before use, and n-BVE was analytical grade, used without further purification. The photoinitiator BP was analytical grade, used withou...

Synthesis of antibacterial polypropylene film with surface immobilized polyvinylpyrrolidone‐iodine complex

“…Within 3 min, nearly 95% of the total monomer had participated in photopolymerization, 42% of which was grafted onto the polymer surface. Later, the increase of C p slowed down while C g still increased, which means that some ungrafted homopolymer chains could be eventually grafted onto the film surface by coupling reactions 33. The ultimate grafting efficiency (defined as W g / W p ) of this photografting system was more than 60%.…”

“…The apparatus and procedure of surface photografting have been described in detail in our previous articles 29–34. Briefly, a predetermined amount of NVP solution containing BP was deposited between two overlapping films with a microsyringe and spread into an even and very thin liquid layer (about 3 μm) under suitable pressure from a top quartz plate.…”

“…In a series of photografting studies, we have facilely grafted various vinyl monomers onto polymer surfaces by a unique film interlayer photopolymerization (FIP) technique 29–34. This study aims at photografting PVP onto polypropylene film first, and subsequently having the surface‐grafted PVP undergo complexation of iodine, thus resulting in a novel antibacterial material with surface immobilized PVP‐I complex (Scheme ).…”

Surface Graft Polymerization of Binary Monomers Maleic Anhydride/n-Butyl Vinyl Ether on the Polypropylene Film via Two-Step Method

“…The CTC between the electron donor-acceptor molecules can be detected by various methods such as UV spectra and nuclear magnetic resonance (NMR), as discussed in detail in our previous article. 26 So far, the formation of CTC has been popularly considered as a major mechanism of alternating copolymerization, although there still exists some controversy on this issue. In this study, we have just implanted the alternating copolymerization into the surface graft polymerization field by means of introducing the electron donor monomer BVE, achieving the grafting of MAH onto the polymer substrate facilely.…”

Two‐stage grafting onto polyethylene fiber by radiation‐induced graft polymerization and atom transfer radical polymerization

“…ATRP initiators have been introduced onto the surfaces of the polyolefin substrates by ultraviolet irradiation and block copolymer chains grafted onto the substrates. [18][19][20][21] However, the structures of the monomers for this method are limited, and it is particularly difficult to graft water-soluble monomers, because the surface of the polyolefin substrate is hydrophobic.…”