Pressure‐Sensitive Adhesive Blend Films for Low‐Tack Applications

Abstract

Polymer blend films consisting of a tacky and a non-adhesive component are promising candidates for low tack applications. Immiscibility of both components results in a phase separation process yielding a tacky matrix with glassy objects embedded. The influence of the blending ratio of the components poly-n-butylacrylate (PnBA) and polystyrene (PS) is addressed. The mechanical information resulting from the tack test shows the possibility to vary the bonding strength of the PSA blend over a wide range. The macroscopic and microscopic structural characterization with optical microscopy and ultra small angle X-ray scattering shows that the blend PnBA:PS exhibits similarities to common filler systems as well as deviates regarding installed structures. Due to the large domain size on a microscopic level, only the tacky component, PnBA, defines the adhesive behavior. The non-adhesive component limits the contact area between the adhesive and the substrate.

Tack Properties of Pressure-Sensitive Adhesive-Coated Fiber Assemblies

“…A home-built apparatus comprising a linear actuator (MP 106E 235.2 DD, Physik Instrumente, Germany), a force sensor of 15 mm length with a measurement range of ±1 N and a compliance of 50 μm/N (XF-3030, Disynet, Germany), and a distance sensor (Kaman KD-2440) for the measurement of displacement was applied for tack experiments. , Data were recorded with a rate of 65/s and a sensitivity of 0.3 mN for the measured force. The moving part in the apparatus was a stainless steel stamp.…”

“…One of the main aspects to follow for reasonable tack experiments is to ensure the perfect parallel alignment of the adhesive layer and the probe. 5 For heterogeneous or curved surfaces, this prerequisite is not given and the experimental technique has to be customized. The size of the probe has to be adapted to the curvature of the surface.…”

“…Force–distance curves are measured during the retraction of the probe. One of the main aspects to follow for reasonable tack experiments is to ensure the perfect parallel alignment of the adhesive layer and the probe . For heterogeneous or curved surfaces, this prerequisite is not given and the experimental technique has to be customized.…”

Unexpected Tribological Synergy in Polymer Blend Coatings: Leveraging Phase Separation to Isolate Domain Size Effects and Reduce Friction

“…The properties of polymer blend films can be varied through careful selection of constituents, composition, and processing methods. Such composites are promising materials for a wide range of industrial applications and demonstrate improvements in mechanical, thermal, optical, and electrical properties , in comparison to analogues made from their homopolymer constituents making polymer blend films candidates for organic optoelectronic devices, pressure sensitive adhesives, batteries, radiation shielding, and anti-reflection coatings. − In addition to typical design considerations such as composition- and constituent-based behavior, the structure and size scale of the phase separated morphology are equally important to the resulting material properties. − …”

“…The route by which phase separation occurs is strongly influenced by the composition and experimental time scales associated with accessing the phase separated regime, and the overall phase separation size scale (domain size) in films largely is controlled by the kinetics of the phase separation process along with the thermodynamic incompatibility of the materials. − Co-continuous structures, which promote mass, charge, or thermal transport through connected paths in the material, can be produced by targeting a composition near the thermodynamic critical blend concentration, through which it is possible to trap the spinodal decomposition phase evolution to maintain the targeted structure. , Droplet structures with small domain sizes, which impact the toughness and stiffness of the polymer blend, can be produced by kinetically trapping a more asymmetric mixture of the blend constituents and accessing the nucleation and growth regime. − As a result of the final film casting and the requirements for kinetic arrest to achieve targeted domain morphologies, processing strongly influences the blend morphology. ,− ,− ,− The trapping of the morphology can be achieved by kinetic arrest of one or both of the polymers, due to polymer vitrification or crystallization as a result of solvent loss during casting. − Composite domain sizes can be tuned further by annealing approaches such as solvent annealing and thermal annealing. , During annealing, the polymer chains have increased mobility, which commonly leads to a growth in domain size as a result of coalescence of the phase separated regions, typically via a coarsening or an Ostwald ripening process . In all, the final film microstructure is governed by the thermodynamics and kinetics of phase separation along with the processing of the material. ,− …”