• Polymer(Korea)
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• v.36 no.3
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• pp.315-320
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• 2012

Ultra violet (UV) curable pressure sensitive adhesives (PSA) were prepared by controlling both the structure of acryl copolymer and the functionality and content of multi-functional monomers. Acryl copolymer worked as the base polymer for giving the tackiness. Multi-functional monomers were used to vary the crosslinked structure and the degree of crosslink. Acryl copolymer showed the reduced peel strength after UV curing by decreasing the content of 2-ethylhexyl acrylate in the monomer composition. Both the peel strength of PSA and the content of residue found on silicon wafer decreased after UV curing by increasing the functionality of multi-functional monomers. UV curable PSA containing 20 phr six-functional monomer showed the higher peel strength before UV curing and the lower peel strength and the least residue on silicon wafer after UV curing.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.449-449
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• 2011

We reported the direct effect of intrinsic surface energy of dry adhesive material to the Van der Waals and capillary forces contributions of the total adhesion force in an artificial gecko-inspired adhesion system. To mimic the gecko foot we fabricated tilted nanohairy structures using both lithography and ion beam treatment. The nanohairy structures were replicated from Si wafer mold using UV curable polymeric materials. The control of nanohairs slanting angles was based on the uniform linear argon ion irradiation to the nanohairy polymeric surface. The surface energy was studied utilizing subsequent conventional oxygen ion treatment on the nanohairy structures which resulted in gradient surface energy. Our shear adhesion test results were found in good agreement with the accepted Van der Waals and capillary forces theory in the gecko adhesion system. Surface energy would give a direct impact to the effective Hamaker constant in Van der Waals force and the filling angle (${\varphi}$) of water meniscus in capillary force contributions of gecko inspired adhesion system. With the increasing surface energy, the effective Hamaker constant also increased but the filling angle decreased, resulting in a competition between the two forces. Using a simple mathematical model, we compared our experimental results to show the quantitative contributions of Van der Waals and capillary forces in a single adhesion system on both hydrophobic and hydrophilic surfaces. We found that the Van der Waals force contributes about 82.75% and 89.97% to the total adhesion force on hydrophilic and hydrophobic test surfaces, respectively, while the remaining contribution was occupied by capillary force. We also showed that it is possible to design ultrahigh dry adhesive with adhesion strength of more than 10 times higher than apparent gecko adhesion force by controlling the surface energy and the slanting angle induced-contact line of dry adhesive the materials.

• Journal of Adhesion and Interface
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• v.20 no.1
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• pp.15-22
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• 2019

In this study, polybutadiene based di-functional urethane acrylate oligomer (PB-UAO) were synthesized from polybutadiene diol and isophorone diisocyanate. And then, pressure sensitive adhesive films were prepared by mixing with synthesized oligomer, tri-functional acrylate monomer (Tris(2-acryloyloxyethyl) isocyanurate (TAOEIC) or Trimethylolpropane triacrylate (TMPTA) or Pentaerythritol triacrylate (PETA)), mono-functional acrylate monomer (Stearyl acrylate) and UV initiators. Effects of types and contents of trifunctional acrylate monomers on peel strength, tensile strength, elongation, thermal stability and water absorption property were studied. As the contents of tri-functional acrylate monomer increased, and as the molecular weight of tri-functional acrylate monomer decreased, peel strength, elongation and water absorption showed a tendency to decrease whereas tensile strength and thermal stability showed a tendency to increase.

• Journal of Adhesion and Interface
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• v.19 no.4
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• pp.145-153
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• 2018

In this study, adhesion promoters with acrylate and carboxylic acid moiety were synthesized from malenized polybutadiene and 2-hydroxyethyl acrylate for producing adhesive film with low water absorption and high adhesion. The surface properties, adhesion strength, mechanical properties and water absorption of adhesive films were characterized according to the amount of acrylate and carboxylic acid in the synthesized adhesion promoters. As the carboxylic acid in the adhesion promoters increased, the adhesion strength showed a tendency to increase and the mechanical properties also improved compared to the commercial adhesion promoter. The compatibility of adhesion promoters improved remarkably due to the presence of polybutadiene (hydrophobic nature), maleic anhydride (hydrophilic nature) and carboxylic acid (hydrophilic nature).

• Journal of Adhesion and Interface
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• v.23 no.4
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• pp.137-143
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• 2022

In this study, the polyurethane acrylates (PUA) resin with good adhesive and flexibility for adhesive for shoes and clothing were synthesized using that poly(tetramethylene adiphate glycol) (PTAd), poly(tetramethylene ether glycol) (PTMG) as polyester polyol and polyether polyol respectively, including 4,4'-methylene diphenyl diisocyanate (MDI), isophorone diisocyanate (IPDI), 1,4-butandiol (1,4-BD), 2-hydroxyethyl methacrylate (2-HEMA) and dibutyl amine (DBA). The effect of polyol blend in the polyurethane acrylate on thermal and mechanical properties, adhesion strength and flexural strength were studied. The glass transition temperature (T_g) of PUA was confirmed in range of -70~-40 ℃. In addition, the glass transition temperature (T_g), decomposition temperature (T_d), tensile strength adhesion strength and heat resistance were increased as increasing of PTAd amount while the elongation, water resistance and flexural properties were decreased. The synthesized polyurethane acrylate with 5:5 ratio of PTAd and PTMG indicated the highest adhesion strength and flexural properties.