Porous polyurea is synthesized by reacting toluene diisocyanate with water in a water–acetone binary solvent. Materials characterization led to the likely conformations of the polymer chains owing to presence of intensive H-bonding.

A porous polyurea (PPU) was prepared through a simple protocol by reacting toluene diisocyanate with water in binary solvent of water-acetone. Its amine group was determined through spectrophotometric absorbance based on its iminization with p-nitrobenzaldehyde amines. PPU was then used as a novel polymer support for enzyme immobilization, through activation by glutaraldehyde followed by immobilization of an enzyme, lipase from Pseudomonas fluorescens (PFL), via covalent bonding with the amine groups of lipase molecules. Influences of glutaraldehyde and enzyme concentration and pH in the process were studied. The results revealed that the activity of the immobilized PFL reached a maximum at GA concentration of 0.17 mol/L and at pH 8. Immobilization rate of 60% or higher for PFL was obtained under optimized condition with an enzyme activity of 283 U/mg. The porous structure of PPU, prior to and after GA activation and PFL immobilization, was characterized. The activity of the immobilized PFL at different temperature and pH and its stability at 40 °C as well as its reusability were tested. The immobilized enzyme was finally used as enantioselective catalyst in kinetic resolution of racemic 1-phenylethanol (1-PEOH), and its performance compared with the free PFL. The results demonstrate that the enzyme activity and stability were greatly improved for the immobilized PFL, and highly pure enantiomers from racemic 1-PEOH were effectively achieved using the immobilized PFL. Noticeable deactivation of PFL in the resolution was observed by acetaldehyde in situ formed. In addition, the immobilized PFL was readily recovered from the reaction system for reuse. A total of 73% of the initial activity was retained after 5 repeated reuse cycles. This work provides a novel route to preparation of a polyurea porous material and its enzyme immobilization, leading to a novel type of immobilized enzyme for efficient kinetic resolution of racemic molecules.

Highly uniform polyurea microspheres are prepared with tunable crosslinking through precipitation polymerization of IPDI with diethylenetriamine (DETA) in water–acetone binary solvent.

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In this study, Metakaolin was used as source material, NaOH and sodium silicate were used as alkali activators.Preparation of three sets of geopolymer samples subject different NaOH concentration from 8 to16mol/L. The effect of alkaline concentration on compressive strength was analyzed. NaOH concentrations at 12mol/L and 16mol/L resulted in high 7-day compressive strengths. And the compressive strength of geopolymeric cement reached the maximum when adding 24mL sodium silicate at SiO2:Na2O ratio 3.3.

Properties of corn starch dissolved in NaOH/urea aqueous solutions were studied in this research, and NaOH/urea at different ratios in aqueous system was used to treat corn starch (CS). NaOH/urea breaks down the structure of CS, resulting in chemical degradation. After degradation, the change of molecular weight was analyzed by GPC-MALLS. The degraded CS (DS) and native CS(NS) were grafted with acrylic acid and compared in FTIR and both DS and NS were successfully grafted with AA.

A pH-sensitive semi-interpenetrating polymer network (semi-IPN) hydrogel based on Konjac glucomannan(KGM) and methylacrylic acid(MAA) was prepared by free radical polymerization at different concentrations of initiator potassium persulfate (KPS) in presence of crosslinker N,N-methylene-bis-acrylamide (MBA). The chemical structure and rheological properties of hydrogels were characterized by FT-IR and rheometry, respectively. In addition, the swelling behavior of the hydrogels were studied in buffer solution at different pHs.