Preparation and characterization of expanded graphite intercalation compound/UV-crosslinked acrylic resin pressure sensitive adhesives

Influence of UV Polymerization Curing Conditions on Performance of Acrylic Pressure Sensitive Adhesives

Acrylic pressure sensitive adhesives (PSAs) were prepared by UV polymerization under varying curing conditions of both fast and slow curing, employing high- and low-intensity UV radiation, respectively. The influences of curing conditions and isobornyl acrylate (IBOA) content on PSA performance were comprehensively investigated by measurement of their rheological, thermal, and adhesive properties. In particular, rheological characterization was accomplished by several analytical methods, such as in situ UV rheology, frequency sweep, stress relaxation, and temperature ramp tests, to understand the effect of the UV curing process and IBOA content on the viscoelastic behavior of acrylic PSAs. The slow-cured samples were observed to form more tightly crosslinked networks compared to the fast-cured. On the other hand, at high loading levels of IBOA, in the case of slow curing, the sample exhibited a contrasting trend, having the shortest stress relaxation time and the highest energy dissipation; this was due to molecular chain scission occurring in the crosslinked polymer during UV polymerization. Consequently, we successfully demonstrated the influence of monomer composition of acrylic PSAs, and that of curing conditions employed in UV polymerization. This study provides valuable insights for the development of crosslinked polymer networks of acrylic PSAs for flexible display applications.

Multiresponsive Shape-Stabilized Hexadecyl Acrylate-Grafted Graphene as a Phase Change Material with Enhanced Thermal and Electrical Conductivities

A phase change material (PCM) essentially making up hexadecyl acrylate-grafted graphene (HDA- g-GN) was fabricated via a solvent-free Diels-Alder (DA) reaction. The novel material exhibits multiresponsive, enhanced thermal and electrical conductivities and valid thermal enthalpy. In addition, the optimum DA reaction conditions were explored. A variety of characterization techniques were used to study the thermal, crystalline, and structural properties of HDA- g-GN. The melting and crystallizing enthalpies of HDA- g-GN were as high as 57 and 55 J/g, respectively. Furthermore, the melting and freezing points of HDA- g-GN were 29.5 and 32.7 °C, respectively. The thermal conductivity of HDA- g-GN reached 3.957 W/(m K), which is well above that of HDA itself and the previously reported PCMs. HDA- g-GN exhibited an excellent electric conductivity of 219 S/m. Compared to HDA, the crystalline activation energy of HDA- g-GN decreased from 397 to 278 kJ/mol (Kissinger model) and 373 to 259 kJ/mol (Ozawa model). Moreover, HDA- g-GN exhibited excellent thermal stability, shape stability, and thermal reliability. More importantly, HDA- g-GN can be employed to realize high-performance light-to-thermal and electron-to-thermal energy conversion and storage, which provides wide application prospects in energy-saving buildings, battery thermal management system, bioimaging, biomedical devices, as well as real-time and time-resolved applications.

Nanocomposite preparation via in situ polymerization of quaternary ammonium salt ion-bonded to graphite platelets

Polymerizable groups attached by ionic interactions to the graphite galleries ensure the polymerization takes place inside the galleries thus enhancing the exfoliation process.