Polymer Poly Diallyldimethylammonium Chloride Research Articles

High performance nanofiltration in BUT-8(A)/PDDA mixed matrix membrane fabricated by spin-assisted layer-by-layer assembly

The membrane fouling is a notorious problem in the practical application of separation membranes. In this study, a mixed matrix membrane based on the MOF BUT-8(A) and the polymer polydiallyldimethylammonium chloride (PDDA) has been prepared on a hydrolyzed polyacrylonitrile (HPAN) substrate by the spin-assisted layer-by-layer assembly (spin-LbL) method. Thanks to the high porosity, high stability, moderate hydrophilicity, and electronegative nature of BUT-8(A), and the good compatibility between BUT-8(A) particles and PDDA polyelectrolytes, the prepared (BUT-8(A)/PDDA)3-HPAN membrane showed high water permeances (over 164 L m−2 h−1 MPa−1) and high rejection rates (over 91.4%) for many dyes in water. Furthermore, the membrane exhibited superior antifouling performance in nanofiltration (NF) with a high flux recovery rate (95.5%) when humic acid (HA) was used as foulant. The high antifouling performance is resulted from tuning hydrophilicity and electronegativity of the membrane surface. These results suggest that the nanofiltration performance of a MOF-based membrane can be well adjusted by a judicious choice of the membrane components and fabrication methods.

Colorimetric determination of carbendazim based on the specific recognition of aptamer and the poly-diallyldimethylammonium chloride aggregation of gold nanoparticles.

This paper proposes the idea of establishing carbendazim (CBZ) colorimetric determination in spiked water samples by specific aptamers of unlabeled carbendazim (CBZ), gold nanoparticles (AuNPs) and cationic polymer poly-diallyldimethylammonium chloride (PDDA). In the absence of CBZ, the CBZ aptamer will react with the cationic polymer PDDA by electrostatic interaction to form a complex structure. Therefore, the gold nanoparticles will remain dispersed due to the lack of PDDA. However, when CBZ is added into the sensory system, the CBZ-specific aptamer can selectively capture CBZ to form a stable complex structure. Due to the consumption of the aptamer, PDDA is unable to interact with the aptamer and begins to induce aggregation of AuNPs, thereby causing the color of the solution to change from red to blue. Colorimetric determination of CBZ based on the specific recognition of aptamer and the PDDA-induced aggregation of AuNPs has a detection limit of 2.2nM, a linear range (R=0.9960) from 2.2 to 500nM. The method has good sensitivity and specificity, and the average recovery of CBZ is 94.9-104.8% in the application of actual water samples. This colorimetric method is simple, time-saving and low requirements for equipment, therefore, it holds great potential for CBZ detection in the environmental water samples.

Preparation of chabazite with mesopores templated from a cationic polymer

Mesoporous chabazite zeolites were prepared by using the cationic polymer polydiallyldimethylammonium chloride (PDADMAC) as template for mesopores and N,N,N-trimethyl-1-adamantammonium hydroxide as structure directing agent for the chabazite framework. The prepared zeolites had large surface areas and significant mesopore volumes that increased with high PDADMAC loading. Nitrogen sorption isotherms of chabazite zeolites with low loadings of PDADMAC (0.8–2.3 wt.%) displayed a composite of Type I and II with a broad H4 hysteresis loop at p/po=0.8–1.0. At a high polymer loading (3.1 wt.%) the resulting zeolite displayed the Type IV sorption isotherm and H3 hysteresis. The chabazite zeolites prepared with 0.8–2.3 wt.% polymer had exponentially decaying mesopore size distribution curves ranging from 2 to 30 nm centred around 4–5 nm. A polymer loading of 3.1 wt.% gave a zeolite with a multimodal meso- and macropore size distribution curve ranging from 2 to 140 nm. Adjusting the synthesis gel composition made it possible to prepare mesoporous chabazite zeolites with PDADMAC loadings up to 3.1 wt.% at Si/Al = 20–70.

Hydrolyzed hexagonal boron nitride/polymer nanocomposites for transparent gas barrier film

A flexible thin gas barrier film formed by layer-by-layer (LBL) assembly has been studied. We propose for the first time that hexagonal boron nitride (h-BN) can be used in LBL assembly. When dispersed in water through sonication-assisted hydrolysis, h-BN develops hydroxyl groups that electrostatically couple with the cationic polymer polydiallyldimethylammonium chloride (PDDA). This process produces hydroxyl-functional h-BN/PDDA nanocomposites. The nanocomposites exhibit well exfoliated and highly ordered h-BN nanosheets, which results in an extremely high visual clarity, with an average transmittance of 99% in the visible spectrum. Moreover, well aligned nanocomposites extend gas diffusion path that reduce water vapor transmission rate to 1.3 × 10−2 g m−2 d−1. The simple and fast LBL process demonstrated here can be applied in many gas barrier applications.

Electrochemistry of Canis familiaris cytochrome P450 2D15 with gold nanoparticles: An alternative to animal testing in drug discovery

This work reports for the first time the direct electron transfer of the Canis familiaris cytochrome P450 2D15 on glassy carbon electrodes to provide an analytical tool as an alternative to P450 animal testing in the drug discovery process. Cytochrome P450 2D15, that corresponds to the human homologue P450 2D6, was recombinantly expressed in Escherichia coli and entrapped on glassy carbon electrodes (GC) either with the cationic polymer polydiallyldimethylammonium chloride (PDDA) or in the presence of gold nanoparticles (AuNPs). Reversible electrochemical signals of P450 2D15 were observed with calculated midpoint potentials (E1/2) of −191 ± 5 and −233 ± 4 mV vs. Ag/AgCl for GC/PDDA/2D15 and GC/AuNPs/2D15, respectively. These experiments were then followed by the electro-catalytic activity of the immobilized enzyme in the presence of metoprolol. The latter drug is a beta-blocker used for the treatment of hypertension and is a specific marker of the human P450 2D6 activity. Electrocatalysis data showed that only in the presence of AuNps the expected α-hydroxy-metoprolol product was present as shown by HPLC. The successful immobilization of the electroactive C. familiaris cytochrome P450 2D15 on electrode surfaces addresses the ever increasing demand of developing alternative in vitromethods for amore detailed study of animal P450 enzymes' metabolism, reducing the number of animals sacrificed in preclinical tests.

Hierarchical Zeolite Beta via Nanoparticle Assembly with a Cationic Polymer

Nanozeolite aggregates with secondary pores of tunable sizes were prepared by the flocculating action of a cationic polymer. Specifically, highly concentrated zeolite beta precursor gels were hydrothermally converted in the presence of the cationic polymer polydiallyldimethylammonium chloride (PDDA). Without polymer, highly crystalline zeolite beta in the form of nanosized particles was obtained from colloidal solutions at high yield. Upon addition of polymer, these nanoparticles were flocculated into self-sustaining, easily retrievable mesoporous aggregates in a one-step procedure at nearly 100% yield, showing interparticle pores with very high mesopore volumes and surface areas. The influence of the amount of polymer, its molecular weight as well as the nature of the silica precursor on pore characteristics, crystallinity, and morphology were studied with nitrogen sorption, mercury intrusion porosimetry and electron microscopy, respectively. Changing the polymer concentration is a powerful parameter to ...