Page 101 - Handbook of Adhesion Promoters

94 Polymer Modification to Improve Adhesion

Figure 6.1. Carboxylic group interactions (a) at acidic pH where there are hydrogen bonds between dimers
created by COOH, and (b) at basic pH, where there are polar ionomeric domains. [Adapted, by permission, from
Gurney, RS; Morse, A; Siband, E; Dupin, D; Armes, SP; Keddie, JL, J. Colloid Interface Sci., 448, 8-16, 2015.]
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located on the neighboring latex particles are minimized. At high pH, the presence of Na +
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cations leads to the formation of polar ionomeric domains (Figure 6.1b). The ionomer
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domains act as weak physical crosslinkers.
The methacrylated β-cyclodextrins, having several polymerizable methacrylate
groups and hydrophilic hydroxyl groups, may promote bonding of dental composites to
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dentin. The study indicated that nonacidic methacrylated β-cyclodextrin monomers can
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be used as adhesion-promoting comonomers.
Halloysite nanotubes were used in nanocomposites via in situ polymerization. 6
Methyl methacrylate was the main monomer copolymerized with a small quantity of ionic
comonomer 2-(methacryloyloxy)ethyltrimethylammonium chloride (MTC) and 2-acryl-
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amido-2-methylpropane sulfonic acid (AMPS). Halloysite was added during the polym-
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erization process. The noncovalent interactions between halloysite and ionic
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comonomers are key factors of successful preparation of nanocomposites. The nanocom-
posites demonstrated excellent mechanical performance due to a strong interfacial adhe-
sion ameliorated by noncovalent interactions enhanced by electrostatic attraction between
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the positively charged matrix of the ionic copolymer and negatively charged halloysite.
The monomer 2-acetoacetoxy ethyl methacrylate was used as a complexing unit to
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produce copper(II) complexes in the coating’s upper surface layer. The copper(II) com-
plexes were stable against washing out and provided biofouling protection to glass and
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metal surfaces. The copper-loaded complexes reduced the growth of Achnanthidium
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spec. and Staphylococcus aureus.
Because of the polarity of comonomers, the ethylene copolymers, such as Lupolen V
and Lucalen, can be welded and bonded more readily by adhesives than the homopoly-
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mers. The low adhesion of polyethylene requires surface pretreatment or copolymeriza-
tion of ethylene with small amounts of polar comonomers which act as adhesion
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promoters. The ethylene copolymers with 10-undecenoic acid and with 5,7-dimethylocta-
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1,6-diene were synthesized. Both exhibit higher adhesion strengths with increasing
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comonomer contents. The 10-undecenoic acid/ethylene copolymers are more effective in
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improving adhesion because of their higher polarity. Propylene was copolymerized with