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The aim of the work is to assess the influence of the method for preparing on the porosity of sintered polytetrafluoroethylene blanks as well as PTFE mixtures with carbon fiber and additives of powdered graphite. The article provides a comparative analysis of the method for preparing influence on the microporosity of sintered blanks made of filled and unfilled polytetrafluoroethylene. Microporosity has been determined through the comparison of the actual and theoretical (for a non-porous material) density of blanks, calculated by the methods of structural mechanics of composites. The studies made it possible to establish that the porosity of the unfilled polytetrafluoroethylene blanks pressed at a pressure of 70…80 MPa stands at 1.3 to 5.9 %. An exception was a specimen obtained by sintering in a jig, which has reached apparent density 2200 kg/m3 equal to theoretical density. It has been established, that the porosity of blanks obtained from polytetrafluoroethylene filled with shredded carbon fiber and powdered graphite stood at 0.4 to 3.9 %. An exception was a specimen with a high mass content of filler (40 %), in which the porosity was 16 %. It has been ascertained that sintering in a constrained state helps to reduce the residual microporosity for both the filled and unfilled polytetrafluoroethylene. This shows the technical efficiency of sintering in a constrained state, despite the increased labor intensity of the manufacturing process and the sophistication of technical equipment.

Iron-containing activated carbon fibers (Fe-ACF) have been prepared by a novel method consisting of mixing an iron precursor with raw pitch before carbon fiber formation, and further CO2 activation of the Fe-CF. The NO adsorption experiment revealed that iron species are accessible to gases and that they activate NO improving adsorption into the fiber microporosity. The chemisorption of NO and the subsequent dimer (N2O2) formation is, in general, the rate-limiting step. Metallic iron and/or partially reduced iron compounds are the most active iron species. However, in the fibers with narrow micropores dimer diffusion in the microporosity is the slowest step and, consequently, an appropriate pore size is required from a kinetic point of view. The most suitable samples prepared were those with pores wider than 0.7 nm which contain partially reduced iron species. Finally, NO adsorbed can be further recovered by heating the spent adsorbents at a quite low temperature (500 K). Fresh and regenerated adsorbents show similar NO adsorption capacity. ; Spanish Government (Project CTQ2005-01358).

Covalent organic-frameworks (COFs) are an emerging class of porous and ordered materials formed by condensation reactions of organic molecules. Recently, the Schiff-base chemistry or dynamic imine-chemistry has been widely explored for the synthesis of COFs. The main reason for this new tendency is based on their high chemical stability, porosity and crystallinity in comparison to previously reported COFs. This critical review article summarizes the current state-of-the-art on the design principles and synthetic strategies toward COFs based on Schiff-base chemistry, collects and rationalizes their physicochemical properties, as well as aims to provide perspectives of potential applications which are at the forefront of research in materials science ; Financial support from Spanish Government (Project MAT2014-52305-P and MAT2013-46753-C2-1-P) and a UCM-BSCH joint project (GR3/14) is acknowledged

The objective of this paper is to get an insight into the chemical activation mechanism using KOH and NaOH as activated agents. Three coals have been selected as carbon precursors. It was found that KOH and NaOH develop a similar narrow microporosity, independently of the coal rank, whereas only KOH generates supermicroporosity. Temperature-programmed desorption experiments, carried out with impregnated anthracite, show differences on the gas evolved during the activated carbon preparation using the two activating agents. Thus, whereas hydrogen profiles are quite similar for both activated agents, the CO and H2O profiles are different. It is remarkable the high amount of H2O evolved at the maximum treatment temperature for both activating agents. The results obtained allow concluding that the chemical activation is due to a combination of different process driving the development of material porosity. ; Spanish Government (project CTQ-2005-01358) and the GV (projects GV/2007/144 and ARVIV/2007/067).

A microfluidic chip has been used to prepare fibres of a porous polymer with high structural order, setting a precedent for the generation of a wide variety of materials using this reagent mixing approach that provides unique materials not accessible easily through bulk processes. The reaction between 1,3,5-tris(4-aminophenyl)benzene and 1,3,5-benzenetricarbaldehyde in acetic acid under continuous microfluidic flow conditions leads to the formation of a highly crystalline and porous covalent organic framework (hereafter denoted as MF-COF-1), consisting of fibrillar micro-structures, which have mechanical stability that allows for direct drawing of objects on a surface ; Financial support from Spanish Government (Projects MAT2013-46753-C2-1-P and CTQ2014-53486-R) and FEDER are acknowledged. A. A. and J. P. L. would like to thank the financial support from the Swiss National Science Foundation (SNSF) through the project no. 200021_160174