Polyhedral Oligomeric Silsesquioxane Induced Thermomechanical Reinforcement in Polymer Films Using Only Parts‐per‐Million Content

Abstract

particle dispersion. The tendency of nano particles to agglomerate has been an unsurpassed hurdle so far. [2,3] The decora tion of nanoparticles surfaces with specific end groups or oligomers to induce homo geneous dispersion and particlepolymer matrix interactions is a cost and time consuming alternative with unconvincing results. [4] Controlling the dispersion of nano particles in a polymeric matrix is key to understand their influence on physical properties. Enabling the dispersion at near unitlevel takes advantage of the high surface area and volume of nano particles and particlelike nanochemicals. Under this condition, recent experimental evidence suggests that only small nano particle content (<5 wt%) is required to produce nanoeffects. [5-10] On the other hand, recent research has shown that when nanoparticles are present in a polymeric matrix, at low con centrations and welldispersed, [7-10] con finement effects can become relevant and the chain dynamics can be modified. [11,12] Therefore, dispersed silica nanoparticles produced entanglement dilation and reduced the melt viscosity of the polymer matrix. [8,13-18] On the other hand, welldispersed layer silicates in polyacrylates and polyelectrolytes significantly attenuated the αrelaxation and increased by orders of magni tude the tensile mechanical modulus by confining the macro molecules between the nanoplatelets. [7,19] There was, however, a penalty on strain at fracture as the nanoparticles acted as stress concentrators thus reducing the extensibility of the nano composite, a result typically seen in reinforced (nano) com posites, i.e., the improvement of tensile mechanical properties degrades performance in extensibility. [7,20] There is, therefore, the notion that confinement induced by welldispersed nanoparticles can induce significant changes to the physical properties of a matrix, and this has been investi gated in model systems [21] in an effort to understand the unu sual properties of materials produced by nature. [22] There is, however, the question of the number of nanoparticles present in the matrix. Recently, the authors reported on a methodology to dis perse untethered polyhedral oligomeric silsesquioxanes (POSS) at a single unit in a lowdensity polyethylene (LDPE) Reinforcement of polymers by nanoparticles has been a challenge due to aggregation and solubility limits, especially at high loads. In this research, a robust and environmentally friendly fabrication approach to produce films reinforced with only parts-per-million (ppm) octamethyl-polyhedral oligomeric silsesquioxane (mePOSS) using conventional extrusion and blow molding processing is demonstrated. The nanocomposites exhibit enhanced thermomechanical properties, and only 160 ppm mePOSS increase the tensile mechanical modulus, E, by ≈120% relative to the neat polymer. Remarkably, there is no penalty on strain at fracture ε f , as usually seen in reinforced (nano) composites. Toughness, yield stress, tear, and puncture resistance are also an increasing function of mePOSS content. F...

Acrylic‐styrene/montmorillonite nanocomposites. Melt viscoelasticity and chain dynamics in nanoconfinement

“…The spatial confinement in polymer chains may arise from: (i) macromolecules spatially confined between layered silicates, 7‐10 (ii) macromolecules constrained within nanopores or nanocylinders, 11‐14 or (iii) polymer fractions located between closely packed nanoparticles 15‐20 …”

Dispersion at Single Unit TiO2 Nanoparticles Reduced Tg, Induced Chain Disentanglement and Reduced Tensile Modulus in Waterborne Acrylic Coatings

“…Recently Romo–Uribe and Lichtenhan demonstrated this concept by thermo‐mechanically reinforcing polyolefins adding only parts‐per‐million (ppm) polyhedral oligomeric silsesquioxane (POSS) nanochemicals, that is, the tensile modulus increased over 100% without penalizing the strain to fracture. [ 10,11 ]…”

“…Therefore, it is the authors’ view that the unusual changes to physical properties of thermoplastics and waterborne coatings utilizing very small amounts of nanofillers are due to nanoconfinement effects. [ 5–7,10,11 ]…”

Development of new active nanocomposite packaging films containing polyhedral oligomeric silsesquioxane for walnut (Juglans regiaL.) kernel packaging

“…POSS is an organic–inorganic hybrid material that was first reported in 1946 26 . The integration of POSS nanoparticles into polymeric materials possesses dramatic improvements such as better thermal and mechanical properties 27–31 . Owing to their relatively inert nature, biocompatibility and health benefits, POSS nanoparticles are preferable biomaterials, including tissue engineering, biomedical application and biosensors 32,33 .…”

“…26 The integration of POSS nanoparticles into polymeric materials possesses dramatic improvements such as better thermal and mechanical properties. [27][28][29][30][31] Owing to their relatively inert nature, biocompatibility and health benefits, POSS nanoparticles are preferable biomaterials, including tissue engineering, biomedical application and biosensors. 32, 33 Janaszewska et al have expressed that POSS nanomaterials did not generate reactive oxygen species and had no adverse effect on cells.…”