Distribution of acrylic acid grafted chains introduced into polyethylene film by simultaneous radiation grafting with water and ethanol as solvents

Abstract

The graft copolymerization of acrylic acid onto low-density polyethylene films by simultaneous g-ray irradiation was carried out. The effect of water and ethanol as grafting solvents on the distribution of grafted poly (acrylic acid) in the low-density polyethylene films was studied with optical microscopy observations of dyed and sliced samples and attenuated total reflection/Fourier infrared spectroscopy analysis. When no vigorous homopolymerization occurred, both polyethylene and poly(acrylic acid) existed in the grafted layer, and the thickness of the grafted layer and the poly(acrylic acid) concentration in the grafted layer increased with an increasing degree of grafting, regardless of the grafting conditions, the former increasing faster than the latter. In comparison with water as the sol-vent, in the absence of the inhibitor, homopolymerization could be suppressed to a certain degree in the ethanol solvent system, whereas in the presence of the inhibitor, obvious homopolymerization occurred at a lower monomer concentration, and both the degree of grafting and the thickness of the grafted layer were lower. Such differences could be explained by the chain transfer and the relatively low solubility of poly(acrylic acid) in ethanol. In addition, an experimental scheme using optical microscopy to observe the dyed and sliced polymers was optimized.

Surface modification of ultra‐flat polydimethylsiloxane by UV‐grafted poly(acrylic acid) brushes

“…Graft polymerization mostly takes place at the interface of solution and solid substrate, forming isolated grains in Figure 1A due to the unevenness of the preabsorbed BP on the PDMS surface. On the other hand, ethanol is an effective chain transfer agent, which could decrease the grafted chain length, whereas water is insensitive to most organic radicals 32. Therefore, the length of chains grafted in ethanol is shorter than that grafted in water.…”

“…After the monomer concentration reaches a certain level, further increase will accelerate the homopolymerization reaction rather than grafting 30. Moreover, intensive homopolymerization leads to not only a significant reduction in monomer for grafting but also a high viscosity of the grafting solution 32. Therefore, less monomer can diffuse into the graft layer, so the graft density decreases.…”

“…On the other hand, ethanol is an effective chain transfer agent, which could decrease the grafted chain length, whereas water is insensitive to most organic radicals. 32 Therefore, the length of chains grafted in ethanol is shorter than that grafted in water. The height of the aggregated chains should be reduced further even if no continuous graft layer is formed.…”

“…30 Moreover, intensive homopolymerization leads to not only a significant reduction in monomer for grafting but also a high viscosity of the grafting solution. 32 Therefore, less monomer can diffuse into the graft layer, so the graft density decreases. Figure 4 also demonstrates the noticeable effect of graft temperature on the grafting process.…”

Stabilization of alumina with polyelectrolyte and comb copolymer in solvent mixtures of water and alcohols

“…The poly(acrylic acid) will be less dissociated in alcohols compared to water, and one may then expect lower zeta potential values. However, the poly(acrylic acid) has lower solubility in alcohol compared to water, 29 and will thus adsorb more strongly to the oxide surface in a suspension containing alcohol. This was also found in the optimization step, where 0.35 wt% PAA gave the lowest viscosity for both ethanol and isopropanol compared to 0.25 wt% PAA in water (Fig.…”