Ionic liquids based on tetraalkylphosphonium cations with long alkyl chains have been used as new compatibilizing agents of biopolymer blends composed of poly(butylene-adipate-co-terephtalate) (PBAT) and poly(lactic acid) (PLA). In this study, the influence of the chemical nature of the counter anion on the morphologies as well as the thermal and mechanical properties of the PBAT/PLA blends has been investigated. First, PBAT/PLA blends filled with a very low amount of ionic liquids (1% wt) have been prepared by melt mixing. Secondly, the effect of ILs on the dispersion of PLA phase within the PBAT matrix was characterized by transmission electronic microscopy (TEM). In a final section, the mechanical behavior of PBAT/PLA blends was studied. A very good compromise was obtained for PBAT/PLA/IL blends with a significant increase of the Young' modulus without loss of the fracture properties.
This paper reports the surface treatment of layered double hydroxide (LDH) by using ionic liquid (IL) composed of phosphonium cation combined with 2-ethylhexanoate (EHT) counter anion as surfactant agent. Then, different amounts (1, 3, 5 and 7 wt %) of thermally stable organically modified LDH (up to 350 °C) denoted LDH-EHT were incorporated into polycaprolactone (PCL) matrix by mechanical milling. The influence of LDH-EHT loading has been investigated on the physical properties, such as the thermal and barrier properties, as well as the morphologies of the resulting nanocomposites. Thus, intercalated or microcomposite morphologies were obtained depending on the LDH-EHT loading, leading to significant reduction of the diffusion coefficient respect to water vapor. The modulation of barrier properties, using low functionalized filler amount, is a very important aspect for materials in packaging applications.
Engineered living microtissues such as cellular spheroids and organoids have enormous potential for the study and regeneration of tissues and organs. Microtissues are typically engineered via self‐assembly of adherent cells into cellular spheroids, which are characterized by little to no cell–material interactions. Consequently, 3D microtissue models currently lack structural biomechanical and biochemical control over their internal microenvironment resulting in suboptimal functional performance such as limited stem cell differentiation potential. Here, this work report on stimuli‐responsive cell‐adhesive micromaterials (SCMs) that can self‐assemble with cells into 3D living composite microtissues through integrin binding, even under serum‐free conditions. It is demonstrated that SCMs homogeneously distribute within engineered microtissues and act as biomechanically and biochemically tunable designer materials that can alter the composite tissue microenvironment on demand. Specifically, cell behavior is controlled based on the size, stiffness, number ratio, and biofunctionalization of SCMs in a temporal manner via orthogonal secondary crosslinking strategies. Photo‐based mechanical tuning of SCMs reveals early onset stiffness‐controlled lineage commitment of differentiating stem cell spheroids. In contrast to conventional encapsulation of stem cell spheroids within bulk hydrogel, incorporating cell‐sized SCMs within stem cell spheroids uniquely provides biomechanical cues throughout the composite microtissues’ volume, which is demonstrated to be essential for osteogenic differentiation.
18 December 2015 in ACS Sustainable Chemistry & Engineering