5045www.MaterialsViews.com wileyonlinelibrary.com capacities were found for materials based on functionalized biological waste [ 13 ] or clay-polymer composites, [ 14 ] but these materials were not selective. Recently, a charge-selective supramolecular hydrogel [ 15 ] with high adsorption capacity was published, but the adsorption process was slow. Materials which show high selectivity as well as high capacity in combination with a fast adsorption process are practically unavailable.We have previously reported a fabrication process for nanoporous membranes based on the self-organization of reactive thermotropic hydrogen-bonded smectic liquid crystals (LCs). [ 16,17 ] The membranes were created by photo-polymerization to lock the smectic structure into a network followed by an alkaline treatment to break the hydrogen bonds. Minute interstices are formed and the smectic nature of the material results in pores with a two-dimensional geometry. Transmission electron microscopy revealed that the width of the straight pores is around 1 nm. A dye was used to measure the local pH in the pores and to prove the porosity. Furthermore, these pores could be fi lled with silver ions, and subsequently reduced to silver nanoparticles. The diameter and orientation of these nanoparticles were controlled by the pore size and shape of the material. [ 18 ] This nanoporous material is expected to be a good candidate for an adsorbent material due to the well-organized structure with high surface area and permeability, which promote the adsorption capacity and kinetics. Furthermore, the confi ned pore interior will be benefi cial for selective adsorption. Nanoporous, LC networks have been studied earlier for use as nanoporous membranes, [19][20][21] in host-guest chemistry, [ 22 ] molecular imprinting, and chiral recognition. To our knowledge, however, nanoporous materials based on reactive thermotropic liquid crystals have never been considered as selective and fast adsorbents with a high capacity. Results and Discussion Preparation and Characterization of a Smectic Liquid Crystalline NetworkThe LC mixture with 4-(6-acryloyloxylhexyloxy)benzoic acid (6OBA) and 1,4-phenylene bis(4-(6-(acryloyloxy)hexyloxy) Responsive Nanoporous Smectic Liquid Crystal Polymer Networks as Effi cient and Selective AdsorbentsHuub P. C. van Kuringen , Geert M. Eikelboom , Ivelina K. Shishmanova , Dirk J. Broer, * and Albertus P. H. J. Schenning * An effi cient and selective porous nanostructured polymer adsorbent is prepared from smectic liquid crystals. The adsorption study is performed by using hydrophilic dyes as water pollutants. The anionic pore interior of the nanoporous polymer is able to selectively adsorb cationic methylene blue over anionic methyl orange. Even zwitter ionic rhodamine B could hardly be adsorbed due to the presence of the anionic group in this dye. The confi ned pore dimensions allow size selective adsorption; a 4 th generation cationic dendrimer is not able to diffuse into the nanometer sized pores. The porous nature of the polymer p...

The monomers 2-methyl-2-oxazine (MeOZI), 2-ethyl-2-oxazine (EtOZI), and 2-n-propyl-2-oxazine (nPropOZI) were synthesized and polymerized via the living cationic ring-opening polymerization (CROP) under microwave-assisted conditions. pEtOZI and pnPropOZI were found to be thermoresponsive, exhibiting LCST behavior in water and their cloud point temperatures (T(CP)) are lower than for poly(2-oxazoline)s with similar side chains. However, comparison of poly(2-oxazine) and poly(2-oxazoline)s isomers reveals that poly(2-oxazine)s are more water soluble, indicating that the side chain has a stronger impact on polymer solubility than the main chain. In conclusion, variations of both the side chains and the main chains of the poly(cyclic imino ether)s resulted in a series of distinct homopolymers with tunable T(CP).

The hydrolysis of PEtOx is studied to evaluate the potential toxicity of partially hydrolyzed polymers that might interfere with its increasing popularity for biomedical applications. The hydrolysis of PEtOx is studied in the presence of digestive enzymes (gastric and intestinal) and at 5.8 M hydrochloric acid as a function of temperature (57, 73, 90, and 100 °C). It is found that PEtOx undergoes negligible hydrolysis at 37 °C and that thermal and solution properties are not altered when up to 10% of the polymer backbone is hydrolyzed. Mucosal irritation and cytotoxicity is also absent up to 10% hydrolysis levels. In conclusion, PEtOx will not decompose at physiological conditions, and partial hydrolysis will not limit its biomedical applications.

Abstract:The solution behavior of a series of poly(2-oxazoline)s with different side chains, namely methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, pentyl, hexyl, heptyl, octyl, nonyl, phenyl and benzyl, are reported in ethanol-water solvent mixtures based on turbidimetry investigations. The LCST transitions of poly(2-oxazoline)s with propyl side chains and the UCST transitions of the poly(2-oxazoline)s with more hydrophobic side chains are discussed in relation to the ethanol-water solvent composition and structure. The poly(2-alkyl-2-oxazoline)s with side chains longer than propyl only dissolved during the first heating run, which is discussed and correlated to the melting transition of the polymers.