End-functionalized polymers by controlled/living radical polymerizations: synthesis and applications

This review focuses on end-functionalized polymers synthesized by controlled/living radical polymerizations and the applications in fields including bioconjugate formation, surface modification, topology construction, and self-assembly.

Synthesis and evaluation of the oil removal potential of 3-bromo-benzimidazolone polymer grafted silica gel

This work reports the synthesis of 3-bromo-benzimidazolone using melt condensation, its polymerization and functionalization on silica which was extracted from diatomaceous earth in our previous work. The synthesized compounds were characterized using FTIR, NMR, SEM-EDS and TEM. The FTIR and NMR spectra of the synthesized benzimidazolones showed the compounds to have several functional groups: A band due to Si-O-C at 1085.41 cm-1, a broad band at 3380 cm-1 and chemical shifts: positive distortionless enhancement by polarization transfer (DEPT) 13C peaks (indicating lack of CH2 and CH3 groups), 1H NMR - 11.053 ppm (N-H), 7.086 ppm (Ar-H); 13C NMR - 155.34 ppm (C[double bond, length as m-dash]O), 101.04 ppm (C-Br) characteristic of benzimidazolones. SEM-EDS of the functionalized silica showed a rough irregular morphology with Si and O as the major elements. Carbon was also present indicating that silica was successfully functionalized with 3-bromo-benzimidazolone and TEM showed interconnected smear-like particles arranged irregularly. The functionalized silica was then applied in the treatment of oily wastewater and factors like initial oil concentration, adsorption dosage and time were optimized using the central composite design of response surface methodology in the design expert software. The amount of oil adsorbed was obtained by quantifying the total organic carbon using TOC test kits. Results showed that the optimum conditions for oil removal were 6650 mg L-1 oil concentration, with adsorbent dosage of 0.004 g and a contact time of 16 h. Under these conditions, the percentage adsorption was 97.9% with a desirability of 0.99. The materials were therefore seen to be applicable to field wastewaters.

Advancements in the preparation and application of monolithic silica columns for efficient separation in liquid chromatography

Fast and efficient separation remains a big challenge in high performance liquid chromatography (HPLC). The need for higher efficiency and resolution in separation is constantly in demand. To achieve that, columns developed are rapidly moving towards having smaller particle sizes and internal diameters (i.d.). However, these parameters will lead to high back-pressure in the system and will burden the pumps of the HPLC instrument. To address this limitation, monolithic columns, especially silica-based monolithic columns have been introduced. These columns are being widely investigated for fast and efficient separation of a wide range of molecules. The present article describes the current methods developed to enhance the column efficiency of particle packed columns and how silica monolithic columns can act as an alternative in overcoming the low permeability of particle packed columns. The fundamental processes behind the fabrication of the monolith including the starting materials and the silica sol-gel process will be discussed. Different monolith derivatization and end-capping processes will be further elaborated and followed by highlights of the performance such monolithic columns in key applications in different fields with various types of matrices.

Tuning Pore Dimensions of Mesoporous Inorganic Films by Homopolymer Swelling

The functionality and applications of mesoporous inorganic films are closely linked to their mesopore dimensions. For material architectures derived from a block copolymer (BCP) micelle coassembly, the pore size is typically manipulated by changing the molecular weight corresponding to the pore-forming block. However, bespoke BCP synthesis is often a costly and time-consuming process. An alternative method for pore size tuning involves the use of swelling agents, such as homopolymers (HPs), which selectively interact with the core-forming block to increase the micelle size in solution. In this work, poly(isobutylene)-block-poly(ethylene oxide) micelles were swollen with poly(isobutylene) HP in solution and coassembled with aluminosilicate sol with the aim of increasing the resulting pore dimensions. An analytical approach implementing spectroscopic ellipsometry (SE) and ellipsometric porosimetry (EP) alongside atomic force microscopy (AFM) and small-angle X-ray scattering (SAXS) in transmission and grazing-incidence (GISAXS) modes enabled us to study the material evolution from solution processing through the manifestation of the mesoporous inorganic film after BCP removal. The in-depth SE/EP analysis evidenced an increase of more than 45% in mesopore diameter with HP swelling and a consistent scaling of the overall void volume and number of pores. Importantly, our analytical toolbox enabled us to study the effect of swelling on the connecting necks between adjacent pores, with observed increases as high as ≈35%, offering novel pathways to sensing, electrochemical, and other mass-transfer-dependent applications.