Effects of Solubility Difference of Tackifier to Respective Components of Block Copolymers on Microphase-Separated Structures in Coated Layers of Pressure-Sensitive Adhesive Prepared by Solution Coating Process

Doi, Takahiro; Takagi, Hideaki; Igarashi, Noriyuki; Sakurai, Shinichi

doi:10.1021/acsapm.0c00845

Cited by 10 publications

(40 citation statements)

References 41 publications

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“…In the current study, we revealed the effects of solubility difference of the tackifier to the respective components of block copolymers on mechanical properties for the same SIS/SI-tackifier specimens used in our previous study . For this purpose, the stress–strain, shear force, and stress-relaxation measurements at various stretching ratios were performed.…”

Section: Introductionmentioning

confidence: 73%

“…Although further reducing the total A fraction from the above-stated case with the A-spherical microdomains suggests seemingly nothing of interest because of no further morphological transition expected, even for this case, it was found in our previous study that controlling the size of the A-spheres was possible. Actually, it was found that the A-spheres became smaller upon the addition of the B-component favorable tackifier molecules . For this particular case, it is also expected that the mechanical properties change (reduction of the tensile modulus/acceleration of the stress relaxation) because the fraction of the loop conformation of the B-block chains is increased while the fraction of their bridge conformation is complementarily decreased.…”

Section: Introductionmentioning

confidence: 94%

“…A pressure-sensitive adhesive utilizes an ABA-type triblock copolymer as a base polymer. , The hard A phase contributes cohesive property, and the soft B phase does initial adhesion to the adherend (so-called tackiness). To sufficiently meet these requirements, diblock copolymers are usually blended with triblock copolymers for the purpose of softening, and the blends are compounded with tackifiers ,− to further impart functionality such as tackiness, adhesiveness, and fixability to an adherend. We quantitatively analyzed by SAXS measurement the effects of solubility difference of the tackifier to the respective components of styrenic block copolymers on microphase-separated structures .…”

Section: Introductionmentioning

confidence: 99%

“…To sufficiently meet these requirements, diblock copolymers are usually blended with triblock copolymers for the purpose of softening, and the blends are compounded with tackifiers ,− to further impart functionality such as tackiness, adhesiveness, and fixability to an adherend. We quantitatively analyzed by SAXS measurement the effects of solubility difference of the tackifier to the respective components of styrenic block copolymers on microphase-separated structures . For this purpose, coated layers were prepared by the solution coating method using a blend of the SIS triblock copolymer and SI diblock copolymer, which forms spherical microdomains of PS in the PI matrix, mixed with three types of tackifiers: aliphatic (C5) resin, aliphatic–aromatic (C5–C9) resin, and rosin ester (RE) resin (the SIS/SI-tackifier specimens).…”

Section: Introductionmentioning

confidence: 99%

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Stress–Strain and Stress-Relaxation Behaviors of Solution-Coated Layers Composed of Block Copolymers Mixed with Tackifiers

et al. 2021

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The relationship between the mechanical properties and the structure of block copolymers mixed with tackifiers whose relative solubility to the respective components of block copolymers differs was examined. Coated layers were prepared by solution coating using a block copolymer composed of polystyrene (PS) and polyisoprene (PI), which forms spherical microdomains of PS in the PI matrix, mixed with three types of tackifiers: aliphatic (C5) resin, aliphatic−aromatic (C5−C9) resin, and rosin ester (RE) resin. Furthermore, the correlation between the changes in the nanostructure and mechanical properties including the stress-relaxation behaviors was clarified by twodimensional small-angle X-ray scattering measurement. The amount of the PI-bridge conformation in the case of C5 resin is the lowest, resulting in the lowest stress. On the contrary, the largest amount of RE resin was solubilized in the PS phase so that it can be considered that pulling out of the PS chains took place easily. We were able to explain the stress-relaxation behavior by fitting with the three-component exponent functions. The triple exponential decay functions indicate the hierarchy of the structures that are the origins of the ″fast mode″ relating to the local relaxation due to the rotation of the repeating unit of polymer chains; the ″intermediate mode″ of the disentanglement of the mid-PI chains; and the ″slow mode″ relating to, in this particular case, pulling out of the PS chains from the PS sphere.

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Section: Introductionmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Stress–Strain and Stress-Relaxation Behaviors of Solution-Coated Layers Composed of Block Copolymers Mixed with Tackifiers

et al. 2021

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“…Usually, it is very difficult to clarify these two phase structures simultaneously by SAXS analysis. Although, Doi et al 25 investigated the phase structure of styrenic block copolymer/tackifier blend by SAXS analysis, they clarified only the influence of tackifier on the phase structure of block copolymer. In our next report, we are going to investigate the phase structure of PBA/RE tackifier blend as a model system using SAXS.…”

Section: Resultsmentioning

confidence: 99%

Phase structure and adhesion properties of acrylic block copolymer/tackifier blends as nanocomposite‐like pressure‐sensitive adhesives

Sasaki¹,

Kashihara

Okada

et al. 2021

J of Applied Polymer Sci

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In a blend of acrylic block copolymer consisting of poly(methyl methacrylate) and poly(n-butyl acrylate) blocks and a special rosin ester resin (RE) tackifier as a model pressure-sensitive adhesive (PSA), RE exists in two states: as nmsized agglomerated particles (A) and as dissolved molecules (B). The effect of A and B ratio on the PSA properties were investigated using REs with four different weight-average molecular weights (M w s) in the range from 680 to 1700.The formation of A increased with increasing of M w because of lowering of miscibility. The glass transition temperature increased with increasing of M w .The tack at lower temperatures and the fracture energy were improved by B, whereas the tack at higher temperatures was improved by A. A and B enhanced the cohesive strength and the wettability of PSA, respectively. However, the improvement of cohesive strength by the RE with highest M w was remarkably low. This seems to be caused by the larger size of agglomerated particles. 1 H pulse nuclear magnetic resonance analysis was useful for estimating the degree of A formation. The model PSA investigated in this study was nanocomposite-like.

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Understanding Humidity‐Enhanced Adhesion of Geckos: Deep Neural Network‐Assisted Multi‐Scale Molecular Modeling

Materzok

Eslami

Gorb

et al. 2023

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A higher relative humidity leads to an increased sticking power of gecko feet to surfaces. The molecular mechanism responsible for this increase, however, is not clear. Capillary forces, water mediating keratin‐surface contacts and water‐induced softening of the keratin are proposed as candidates. In previous work, strong evidence for water mediation is found but indirect effects via increased flexibility are not completely ruled out. This article studies the latter hypothesis by a bottom‐up coarse‐grained mesoscale model of an entire gecko spatula designed without explicit water particles, so that capillary action and water‐mediation are excluded. The elasticity of this model is adjusted with a deep neural network to atomistic elastic constants, including water at different concentrations. Our results show clearly that on nanoscopic flat surfaces, the softening of keratin by water uptake cannot nearly account for the experimentally observed increase in gecko sticking power. Here, the dominant mechanism is the mediation of keratin‐surface contacts by intervening water molecules. This mechanism remains important on nanostructured surfaces. Here, however, a water‐induced increase of the keratin flexibility may enable the spatula to follow surface features smaller than itself and thereby increase the number of contacts with the surface. This leads to an appreciable but not dominant contribution to the humidity‐increased adhesion. Recently, by atomistic grand‐canonical molecular dynamics simulation, the room‐temperature isotherm is obtained for the sorption of water into gecko keratin, to the authors’ knowledge, the first such relation for any beta‐keratin. In this work, it relates the equilibrium water content of the keratin to the ambient relative humidity.

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Effects of Solubility Difference of Tackifier to Respective Components of Block Copolymers on Microphase-Separated Structures in Coated Layers of Pressure-Sensitive Adhesive Prepared by Solution Coating Process

Cited by 10 publications

References 41 publications

Stress–Strain and Stress-Relaxation Behaviors of Solution-Coated Layers Composed of Block Copolymers Mixed with Tackifiers

Stress–Strain and Stress-Relaxation Behaviors of Solution-Coated Layers Composed of Block Copolymers Mixed with Tackifiers

Phase structure and adhesion properties of acrylic block copolymer/tackifier blends as nanocomposite‐like pressure‐sensitive adhesives

Understanding Humidity‐Enhanced Adhesion of Geckos: Deep Neural Network‐Assisted Multi‐Scale Molecular Modeling

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