A Review of Cellulose and Cellulose Blends for Preparation of Bio-derived and Conventional Membranes,Nanostructured Thin Films,and Composites

Cellulose has been used as a raw material for the manufacture of membranes and fibers for many years. This review gives the background of the most recent methods of treating or dissolving cellulose, and its derivatives to form polymer films or membranes for a variety of applications. Indeed, some potential applications of bacterial cellulose, nanofibrillar cellulose (NFC) for films showing enhanced barrier characteristics are reviewed as well as the utilization of cellulose nanonocrystals (CNC) for production of highly oriented super strong films or thin films is discussed. Because of the success of the Lyocell process as well as the amine/metal thiocyanate solvent blends of cellulose and other polysaccharides like starch, chitosan, and other natural polymers. Consequently, the use of cellulose (or its derivatives) and another polysaccharide dissolved as a blend is also elaborated. It is our hope that the reader will want to follow up and investigate these new systems and use them to develop end use materials for all sorts of applications, from medical to water filtration, or electrogels for use in batteries.     

Radiation‐grafted ion‐exchange membranes: Influence of the initial matrix on the synthesis and structure

A series of commercial fluoropolymer films was irradiated with an electron beam, grafted with styrene, and sulfonated. The influence of the initial fluoropolymer on the grafting yields and the properties of the grafted and sulfonated membranes were investigated. The same synthesis procedure can be followed for most fluoropolymers and samples with a similar degree of grafting, and a homogenous polystyrene distribution can be prepared by varying the absorbed dose. The main difference among different fluoropolymer‐based membranes is the water uptake from liquid water that has a roughly linear dependence on the crystallinity of the sample. The more amorphous the initial material, the greater the water uptake. Mechanical properties of the membranes at 50% relative humidity differ less than those of the starting materials and are comparable to those of Nafion® 105. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3008–3017, 2001     

Synthesis and properties of poly(arylene ether)s bearing sulfonic acid groups on pendant phenyl rings

Two kinds of new aromatic poly(arylene ether)s containing sulfonic acid groups were synthesized. Polymer 1 composed of tetraphenylphenylene ether and perfluorobiphenylene units was sulfonated with chlorosulfonic acid. Sulfonation took place only at the para position of the pendant phenyl rings. The average degree of sulfonation per repeating unit (m) was controlled from 1 to 4. Sulfonated polymer 2 with m = 3 was soluble in methanol and dimethyl sulfoxide and swelled in water. Incorporating bis(3,5‐dimethylphenyl)sulfone moieties into the sulfonated polymer imparts less methanol affinity. Polymers 4 with 30–65 mol % tetrakis(sulfophenyl)phenylene ether units has high decomposition temperatures above 300 °C, hydrophilicity, and good hydrolytic stability. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3211–3217, 2001     

Synthesis of highly sulfonated poly(arylene ether sulfone) random (statistical) copolymers via direct polymerization

Novel biphenol‐based wholly aromatic poly (arylene ether sulfones) containing pendant sulfonate groups were prepared by direct aromatic nucleophilic substitution polycondensation of disodium 3,3′‐disulfonate‐4,4′‐dichlorodiphenyl sulfone (SDCDPS), 4,4′‐dichlorodiphenylsulfone (DCDPS) and biphenol. Copolymerization proceeded quantitatively to high molecular weight in N‐methyl‐2‐pyrrolidinone at 190°C in the presence of anhydrous potassium carbonate. Tough membranes were successfully cast from the control and the copolymers, which had a SDCDPS/DCDPS mole ratio of either 40:60 or 60:40 using N,N‐dimethylactamide; the 100% SDCDPS homopolymer was water soluble. Short‐term aging (30 min) indicates that the desired acid form membranes are stable to 220°C in air and conductivity values at 25°C of 0.110 (40%) and 0.170 S/cm (60%) were measured, which are comparable to or higher than the state‐of‐the art fluorinated copolymer Nafion 1135 control. The new copolymers, which contain ion conductivity sites on deactivated rings, are candidates as new polymeric electrolyte materials for proton exchange membrane (PEM) fuel cells. Further research comparing their membrane behavior to post‐sulfonated systems is in progress.     

微孔PI气体分离膜的研究进展

自具微孔材料(PIMs)由于自身刚性分子链的扭曲折叠等会产生高比表面积的微孔结构,相应的膜材料具有优异的气体分离性能。将刚性扭曲的结构单元引入到聚酰亚胺(PI)主链中就得到自具微孔PI。微孔型PI是近年来发展的一种新型PI,其微孔结构使得PI膜的气体分离性能得到很大提升,其中气体渗透系数的提升尤为显著,且保持了传统PI良好的热稳定性、化学稳定性及高力学强度等性质。本文重点介绍了微孔PI以及基于微孔PI复合膜的最新研究进展,并对其未来发展趋势进行了展望。     

Synthesis and Characterization of New Phosphorus Containing Sulfonated Polytriazoles for Proton Exchange Membrane Application

Sulfonated polytriazoles have drawn a great attention as high performance polymers and their good film forming ability. In the present study, a phosphorus containing new diazide monomer namely, bis-[4-(4′-aminophenoxy)phenyl]phenylphosphine was synthesized and accordingly, a series of phosphorus containing sulfonated polytriazoles (PTPBSH-XX) was synthesized by reacting equimolar amount of this diazide monomer (PAZ) in combination with another sulfonated diazide monomer (DSAZ) and a terminal bis-alkyne (BPALK) by the Cu (I) catalyzed azide–alkyne click polymerization. The polymers were characterized by nuclear magnetic resonance (¹H, ¹³C, ³¹P NMR) and Fourier transform infrared spectroscopic techniques. The sulfonic acid content of the copolymers also determined from the different integral values obtained from the ¹H NMR signals. The small-angle X-ray scattering results unfolded the well-separated dispersion of the hydrophilic and hydrophobic domains of the polymers. As a whole, the copolymer membranes displayed sufficient thermal, mechanical, and oxidative stabilities high with high proton conductivity and low water uptake that are essential for proton exchange membrane applications. The copolymers exhibited oxidative stability in the range of 15–24 h and had proton conductivity values were found as high as 38–110 mS cm⁻¹ at 80 °C in completely hydrated condition. Among the all copolytriazoles, PTPBSH-90 (BPALK:DSAZ:PAZ = 100:90:10) having IEC_W = 2.44 mequiv g⁻¹, showed proton conductivity as high as 119 mS cm⁻¹ at 90 °C with an activation energy of 10.40 kJ mol⁻¹ for the proton conduction. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 263–279     

The melt hollow fiber spinning process: steady-state behavior,sensitivity and stability

The rheology of the melt hollow fiber spinning process is examined in the thin filament limit. The resulting thin filament equations are also applicable to single-phase and two-phase extensional flows. Using a novel numerical solution procedure, the sensitivity of the fiber spinning equations to material property and process variations is investigated. Fiber geometry is directly controlled by the mass flowrates of the core and clad fluids while the spinline tension is most strongly influenced by clad viscosity. A maximum can occur in the clad stress profile if a core liquid is used and the ratio of core to clad viscosity increases greatly with temperature. Isothermal spinning of high viscosity clad liquids with either a core gas or liquid is unstable for draw ratios greater than 20.2 as found for solid fibers.     

Synthesis of copolyimides based on room temperature ionic liquid diamines

Block copolyimides based on aromatic dianhydrides and diamines copolymerized with diamino room temperature ionic liquid (RTIL) monomers were synthesized over a range of compositions. Specifically, two diamino RTILs, 1,3‐di(3‐aminopropyl) imidazolium bis[(trifluoromethyl)sulfonyl] imide ([DAPIM] [NTf₂]) and 1,12‐di[3‐(3‐aminopropyl) imidazolium] dodecane bis[(trifluoromethyl) sulfonyl] imide ([C₁₂ (DAPIM)₂] [NTf₂]₂) were synthesized using a Boc protection method. The two RTILs were reacted with 2,2‐bis(3,4‐carboxylphenyl) hexafluoropropane dianhydride (6FDA) to produce 6FDA‐RTILs oligomers that formed the RTIL component for the block copolyimides. The oligomers were reacted with 6FDA and m‐phenylenediamine (MDA) at oligomer concentration from 6.5 to 25.8 mol % to form block copolyimides. Increasing the concentration of the 6FDA‐RTIL oligomer in the block copolyimides resulted in a decrease in the thermal degradation temperature, glass transition temperature and an increase in the density. The gas permeability of the RTIL based block copolyimide decreased but the ideal permeability selectivity for CO₂/CH₄ gas pair increased relative to the pure 6FDA‐MDA. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4036–4046, 2010