Synthesis and Characterization of Amphiphilic Copolymer Acrylic Acid-co-p-Chloromethylstyrene

The free radical copolymerization of acrylic acid (M₁) with p-chloromethylstyrene (M₂) in dioxane and in the presence of α,α′-azobisisobutyronitrile (AIBN) at 65°C is reported. Copolymer compositions of six copolymer samples obtained from feed ratios of M₁:M₂ = 95.2:4.8 to 21.4:78.6 were determined by ¹H-NMR. The reactivity ratios of AA/p-CMS copolymerization system calculated by the F-R method were r ₁ = 0.50 ± 0.06 and r ₂ = 1.52 ± 0.15, almost the same as r ₁ = 0.43 ± 0.21 and r ₂ = 1.31 ± 0.14 by the extended K-T method. On the basis of the reactivity ratios of two monomers, the sequence length distribution in the AA/p-CMS copolymers was obtained. For f₂ = 4.77%, the monomer unit of p-CMS is individually separated in the chain of AA; for f₂ = 35.53%, the alternating tendency prevails and a large number of mono-sequences are formed. The number-average ( _n) and weight-average ( _w) molecular weights were determined by gel permeation chromatography. The effect on molecular weights of feed composition is also discussed. In the presence of constant initiator concentration, the gradual increase in the ratio of M₂:M₁ (from14.7:85.3 to 78.6:21.4) was accompanied by a decrease in molecular weights ( _n from 11907 to 3961).     

Preparation and Characterization of Quaternized Chitosan Under Microwave Irradiation

For the first time, N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (HTCC) was prepared through a fast, easy and efficient method with the assistance of microwave irradiation, and the quaternized chitosan was also degraded via the microwave irradiation. A comparative study was performed by using the conventional heating method to prepare HTCC. The structure and property of the quaternized chitosan obtained by these two methods were characterized by GPC, XRD, FTIR, NMR, TG and elemental analysis. It was shown that quaternized chitosan was successfully prepared within 50 min via microwave irradiation method, while a much longer time of 6–7 h was needed with the conventional heating method. The substitutions both occurred on the C2 position of chitosan with the two different methods, and their HTCC products had weight average similar molecular weight (Mw), structure and thermal stability. The HTCC prepared by the microwave irradiation method had a little lower degree of substitution (DS) than those prepared via conventional heating with the same mole ratio (6:1) of the intermediate to chitosan. The degradation study showed that the Mw of HTCC decreased rapidly from 4.6 × 10⁵ to 1.1 × 10⁵ in 1 h under microwave irradiation, while it only decreased from 4.6 × 10⁵ to 2.1 × 10⁵in 1 h through conventional heating degradation. These results revealed that microwave irradiation is a more efficient and environment-friendly way to obtain the water-soluble chitosan derivatives and their degraded products.     

Preparation and Characterization of PVC-based Photoresponsive Polymers Containing Azo-chromophores

New strategy was developed for the preparation of the photoresponsive polymers containing azo-chromophores as side-groups from the active chlorine atoms of polyvinyl chloride (PVC). The anilinated polyvinyl chloride precursors, anilinated polyvinyl chloride (PVC-An) and o-chloroanilinated polyvinyl chloride (PVC-oClAn), synthesized chemically by reacting PVC with sodium aniline (o-chloroaniline) salt. Then the two novel PVC-based polymers functionalized with azo-chromophores (PVC-AZ-An and PVC-o-AZ-NP) were synthesized via the azo-coupling reactions of the anilinated polyvinyl chloride precursors (PVC-An and PVC-oClAn) with the diazonium salts of aniline and alpha naphthylamine, respectively. The structures of polymers were confirmed by FTIR and ¹H–NMR. The UV-Vis spectra of the obtained polymer in THF solution showed that the π ?π ? absorption band of PVC-o-AZ-NP shifted to longer wavelength (red-shifted) due to the influence of auxochrome (-Cl) compared to the π ?π ? absorption band of PVC-AZ-An.     

Preparation and solution properties of a novel cationic hydrophobically modified polyacrylamide for enhanced oil recovery

Abstract

A novel cationic water-soluble monomer allyldimethylisooctylammonium bromide (ADIAB) containing a short-chain alkane was synthesized successfully. This monomer was copolymerized with acrylamide and sodium acrylate to produce hydrophobically modified polyacrylamide (HMPAM) using solution polymerization without surfactants. The structures of monomer ADIAB and HMPAM were characterized with infrared spectroscopy and nuclear magnetic resonance spectroscopy. Influence of preparation condition on viscosities of products was studied. The aqueous solution viscosity of the terpolymer was also investigated as functions of concentration, temperature and salinity. The results showed that when the temperature exceeds the 60?°C and NaCl concentration exceeds about 2000?mg/L, the temperature and salt tolerance characters of terpolymer were demonstrated. The enhanced oil recovery tests were initially carried out using homogeneous sandpack models.     

Temperature/Light Dual‐Responsive Inclusion Complexes of α‐Cyclodextrins and Azobenzene‐Containing Polymers

Three kinds of photoresponsive copolymers with azobenzene side chains were synthesized by radical polymerization of N‐4‐phenylazophenylacrylamide (PAPA) with N‐isopropylacrylamide (NIPAM), N,N‐diethylacrylamide (DEAM) or N,N‐dimethylacrylamide (DMAM) respectively. Their structures were characterized by FT‐IR, ¹H‐NMR and UV/Vis spectroscopy. Their reversible photoresponses were studied with or without α‐cyclodextrin (α‐CD), which showed that both the copolymers and their inclusion complexes with α‐CD underwent rapid photoisomerization. The lower critical solution temperature (LCST) of the copolymers and their inclusion complexes with α‐CD were investigated by cloud point measurement, which showed that the LCST of three kinds of copolymers increased largely after adding α‐CD. After UV irradiation on the solutions of copolymers and their inclusion complexes, the LCST of the copolymers increased slightly with the absence of α‐CD, while decreased largely with the presence of α‐CD. Furthermore, the LCST reverted to its originality after visible light irradiation. This change of LCST could be reversibly controlled by UV and visible light irradiation alternately. In particular, in the copolymer of PAPA and DMAM, the reversible water solubility of the inclusion complexes could be triggered by alternating UV and visible light irradiation.     

A model validation and consensus building environment

Over half of the failures in drug development are due to problems with the absorption, distribution, metabolism, excretion, and toxicity, or ADME/Tox properties of a candidate compound. The utilization of in silico tools to predict ADME/Tox and physicochemical properties holds great potential for reducing the attrition rate in drug research and development, as this technology can prioritize candidate compounds in the pharmaceutical R&D pipeline. However, a major concern surrounding the use of in silico ADME/Tox technology is the reliability of the property predictions. Bio-Rad Laboratories, Inc. has created a computational environment that addresses these concerns. This environment is referred to as KnowItAll®. Within this platform are encoded a number of ADME/Tox predictors, the ability to validate these predictors with/without in-house data and models, as well as build a ‘consensus’ model that may be a much better model than any of the individual predictive model. The KnowItAll® system can handle two types of predictions: real number and categorical classification.     

Catalytic effect analysis of metallic additives on light crude oil by TG and DSC tests

This research aimed at the investigation of the effect of different metallic additive on the combustion and kinetic behavior of crude oil. For this purpose, the thermal behavior of the oil-only and oil–metallic salts mixtures were studies by the thermogravimetry (TG)/derivative thermogravimetry and differential scanning calorimetry (DSC) on heating rate at 10 °C min^?1. The result shows that Dagang crude oil exhibited apparent low temperature oxidation (LTO), fuel deposition, and high temperature oxidation processes. With the addition of metallic salts, the LTO process has been shortened and samples added CuSO₄, CrCl₃·6H₂O, and AlCl₃·6H₂O achieved a much lower peak temperature than that of oil. Based on the Arrhenius model, metallic additives were proven to have obvious influence on the combustion activation energy. And, by comprehensive analysis of TG/DSC profile and activation energy, ZnSO₄ exhibited a positive influence on light crude oil combustion during the high pressure air injection process.