Fabio Bazzarelli

An Efficient Polymer Molecular Sieve for Membrane Gas Separations

Bicyclic Bridge to Improvement Polymers of intrinsic microporosity are a recently developed class of contorted rigid glassy ladderlike polymers having very high free volume (open internal spaces). The intrinsic porosity of these materials has made them of interest for ultrahigh permeability gas separation membranes. However, while the polymers show good gas permeability, they have only moderate gas selectivity. Carta et al. (p. 303; see the Perspective by Guiver and Lee) hypothesized that if they could replace the dioxin-like rings in their polymers with stiffer bridged bicyclic rings, they could improve the membrane properties of the polymer. By exploiting reactions connected to the formation of Trögers base to form the multiple covalent bonds needed to make the bicyclic rings, the resulting polymers showed significantly improved selectivity and permeability. Intrinsically porous polymers made using reactions associated with Tröger’s base manifested enhanced membrane properties. [Also see Perspective by Guiver and Lee] Microporous polymers of extreme rigidity are required for gas-separation membranes that combine high permeability with selectivity. We report a shape-persistent ladder polymer consisting of benzene rings fused together by inflexible bridged bicyclic units. The polymer’s contorted shape ensures both microporosity—with an internal surface area greater than 1000 square meters per gram—and solubility so that it is readily cast from solution into robust films. These films demonstrate exceptional performance as molecular sieves with high gas permeabilities and good selectivities for smaller gas molecules, such as hydrogen and oxygen, over larger molecules, such as nitrogen and methane. Hence, this polymer has excellent potential for making membranes suitable for large-scale gas separations of commercial and environmental relevance.

A Spirobifluorene‐Based Polymer of Intrinsic Microporosity with Improved Performance for Gas Separation

A highly gas-permeable polymer with enhanced selectivities is prepared using spirobifluorene as the main structural unit. The greater rigidity of this polymer of intrinsic microporosity (PIM-SBF) facilitates gas permeability data that lie above the 2008 Robeson upper bound, which is the universal performance indicator for polymer gas separation membranes.

Nanoporous Organic Polymer/Cage Composite Membranes

Organic?organic composite membranes are prepared by in?situ crystallization of cage molecules in a polymer of intrinsic microporosity. This allows a direct one-step route to mixed-matrix membranes, starting with a homogeneous molecular solution. Extremely high gas permeabilities are achieved, even after ageing for more than a year, coupled with good selectivity for applications such as CO2 recovery.

Synthesis and gas permeation properties of novel spirobisindane-based polyimides of intrinsic microporosity

Three novel polyimides (PIM-PIs) with characteristics similar to a polymer of intrinsic microporosity (PIM) were prepared by the reactions of a novel spirobisindane-based dianhydride with appropriate aromatic diamines. A polymerisation procedure via in situ ester precursor formation provided PIM-PIs with very high molar masses. The gas permeation parameters (permeability (P), diffusion (D) and solubility (S) coefficients) were determined for these polymers. These PIM-PIs exhibit both high apparent surface areas and high gas permeability coefficients, greater than those of most polyimides studied so far and only slightly smaller than the permeability coefficients of the archetypal polymer of intrinsic microporosity, PIM-1. Treatment of the films with alcohols results in significant increases the P values, just as has been noted for PIM-1. This enhancement is caused by an increase of the diffusion coefficients, while the solubility coefficients are much less sensitive to this treatment. However, PIM-PIs are distinguished by extremely high gas solubility coefficients a property, which is characteristic to all PIMs.

Microencapsulation by Membrane Emulsification of Biophenols Recovered from Olive Mill Wastewaters

Biophenols are highly prized for their free radical scavenging and antioxidant activities. Olive mill wastewaters (OMWWs) are rich in biophenols. For this reason, there is a growing interest in the recovery and valorization of these compounds. Applications for the encapsulation have increased in the food industry as well as the pharmaceutical and cosmetic fields, among others. Advancements in micro-fabrication methods are needed to design new functional particles with target properties in terms of size, size distribution, and functional activity. This paper describes the use of the membrane emulsification method for the fine-tuning of microparticle production with biofunctional activity. In particular, in this pioneering work, membrane emulsification has been used as an advanced method for biophenols encapsulation. Catechol has been used as a biophenol model, while a biophenols mixture recovered from OMWWs were used as a real matrix. Water-in-oil emulsions with droplet sizes approximately 2.3 times the membrane pore diameter, a distribution span of 0.33, and high encapsulation efficiency (98% ± 1% and 92% ± 3%, for catechol and biophenols, respectively) were produced. The release of biophenols was also investigated.