Miscibility and morphological properties of quaternized polysulfone blends with polystyrene and poly(4‐vinylpyridine)

Quaternized polysulfones were synthesized by the quaternization reaction of chloromethylated polysulfone with different tertiary amines −N,N‐dimethylethylamine (DMEA) and N,N‐dimethyloctylamine (DMOA), respectively. New blends from these quaternized polysulfones (PSF‐DMEA or PSF‐DMOA) with polystyrene (PS) or poly(4‐vinylpyridine) (P4VP) were prepared by the solution casting method. Pure quaternized polysulfones, in N,N‐dimethylformamide (DMF)/methanol (MeOH) and DMF/water solvent/nonsolvent mixtures, and their blends with PS and P4VP, as well, were investigated by shear viscometry and viscoelasticity, atomic force microscopy, differential scanning calorimetry, and surface properties. The results obtained revealed that the blends have good miscibility. Surface morphology is characterized by roughness and nodules formations, depending on the alkyl radical lengths, composition of the polymer mixtures, including specific electron‐donor or electron‐acceptor characteristics of polymers. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Polymers with Pendent Functional Groups. II. Investigation on the Chloromethylation of Polystyrene

The study attempted to establish the optimum reaction conditions for obtaining soluble chloromethylated polystyrene with a transformation degree higher than 50%. A paraformaldehyde and chlorotrimethylsilane mixture as chloromethylation agent and SnCl₄ as catalyst were used. The transformation degree followed by the chlorine content depends on the following parameters: temperature, time, and [SnCl₄]/[PS] and [Me₃ClSi]/[PS] molar ratios.     

烧结造块粉状物料的造球机理

提高粉状物料造球效果的技术措施是基于对微造球机理的认识。假定了基于第一中心和第二中心的两种微造球机理。为了描述和解释原料粒度结构组成对微造球机理的影响,定义了两个新参数,即N1和N2两个比率,并介绍了关于N1、N2重要性的的试验结果和相关技术措施。     

Characterisation and corrosion resistance of the electrodeposited hydroxyapatite and bovine serum albumin/hydroxyapatite films on Ti–6Al–4V–1Zr alloy surface

A new titanium base Ti–6Al–4V–1Zr alloy covered with hydroxyapatite or bovine serum albumin/hydroxyapatite was characterized in this paper in order to be used as implant material. Following techniques were used: linear polarization, electrochemical impedance spectroscopy, scanning electronic microscopy, Fourier transform infrared spectroscopy and atomic force microscopy. For HA or BSA/HA covered alloy, the electric equivalent circuit contains two time constants (for the passive film and for coatings). The resistance of the protective films increased in time and BSA/HA coating was slightly rougher than HA coating, this situation being favourably to the cell adhesion.     

Synthesis and characterization of phosphorus‐containing polysulfone

Chemical modification of a chloromethylated polysulfone (CMPS) was performed by reacting the chlorometyl group with P? H bond of 9,10‐dihydro‐oxa‐10‐phosphophenanthrene‐10‐oxide (DOPO). A kinetic study of phosphorylation of CMPS with different chlorine content was reported. The obtained polymers bearing cyclic bulky groups containing phosphorus were characterized by analytical methods; Fourier transforms spectroscopy (FTIR), and nuclear magnetic resonance spectroscopy (NMR). The thermal stability of phosphorus‐modified polysulfone was evaluated by dynamic thermogravimetric analysis in nitrogen gas. The polymers were readily soluble in polar organic solvent, such as N‐methylpyr‐rolidone (NMP), N,N‐dimethylacetamide (DMAc), and N,N‐dimethylformamide (DMF). Differential scanning calorimeter (DSC) and dynamic mechanical analysis (DMA) proved an amorphous morphology of these polymers. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Layer by layer deposition of hydroxyapatite onto the collagen matrix

Layer by layer (LbL) deposition is a useful method for deposition of many inorganic (including metals, oxides and phosphates) and organic (including polymers and proteins) components on a large range of substrates. The LbL deposition of hydroxyapatite (HA) onto a collagen matrix involves HA synthesis on the collagen matrix starting from electrically charged precursors such as Ca²⁺ and PO₄³⁻ at a proper pH to precipitate the desired calcium phosphate.The LbL deposition process was continuously monitored in order to study the amount of HA deposited in each layer. The deposition of the first layers of HA was concluded to be highly influenced by the collagen matrix. When the collagen matrix is crosslinked with glutaraldehyde, the matrix structure is not modified during the deposition, and the porosity will decrease with the number of layers until saturation is reached. Following pore saturation, HA will be only deposited onto the mineralized collagen matrix surface. The obtained composite materials were characterized by XRD, SEM, DTA-TG and FTIR.     

Surface properties and antibacterial activity of quaternized polysulfones

Novel quaternized polysulfones (PSFs) with two ionic chlorine contents were investigated, namely, their morphology and antimicrobial activity. Atomic force microscopy (AFM) studies on their membranes showed ordered domains, in which pores and nodules of different sizes and intensities were distributed. The charge density of the quaternized PSFs and the history of the membranes formed from solutions in solvent/nonsolvent mixtures influenced the different aspects of the surface images. The adhesion of Escherichia coli ATCC 10536 and Staphylococcus aureus ATCCC 6538 microorganisms to solutions of the modified PSFs is discussed in correlation with the hydrophobic/hydrophilic properties of the studied polymers and microorganisms. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Surface analysis and electrochemical behavior of Ti–20Zr alloy in simulated physiological fluids

An advanced Ti–20Zr alloy was obtained by double vacuum melting in a semi-levitation furnace with cold crucible. The alloy shows fully lamellar α + β microstructure. Cyclic potentiodynamic polarization curves revealed that the alloy passivated easier, more rapid than Ti, having a more stable passive film in Ringer solutions of different pH values, simulating severe functional conditions of an implant. In neutral and alkaline Ringer solutions, the alloy passive film improved its properties in time (1500 h) by the deposition of protective hydroxyapatite, as was demonstrated by XPS, SEM, EDX, Raman and FT-IR measurements. Alloy presented lower corrosion rates and higher polarization resistances (from linear polarization measurements) than those of Ti (tens of times) proving a more resistant passive film. Alloy open circuit potentials had more electropositive values in comparison with Ti and tended to nobler values in time, which denote better passive state and its enhancement in time, due to the new depositions from the physiological solutions. Nyquist and Bode spectra depicted a more protective passive film on the alloy surface than on Ti surface. The passive film is formed by two layers: an inner barrier layer and an outer porous layer. An electric equivalent circuit with two time constants was modeled.