Fabrication and cytotoxicity assessment of novel polysiloxane/bioactive glass films for biomedical applications

This work evaluates for the first time the cyto-compatibility of silicone (polysiloxane)/bioactive glass composite films produced by dip coating on stainless steel substrates using osteoblast-like (MG-63) cells. With the aim of creating corrosion resistant coatings for biomedical applications, bioactive glass (BG) of 45S5 composition was used as a filler in conjunction with commercial silicones (MK and H62C). Bioactive glass has the property of forming a direct bond to living bone, and polysiloxane is an attractive candidate for protective coatings due to its resistance to oxidation and corrosion. Suspensions based on polysiloxanes (MK/H62C) and micro-sized BG fillers were used for dip coating stainless steel substrates at room temperature, followed by curing in oxidative atmosphere at 260 °C and 500 °C. Fourier transform infrared spectroscopy (FTIR) analysis revealed the presence of Si–O–Si, Si–OR, Si–CH₃ and Si–OH groups on the substrate. Field emission scanning electron microscopy showed that the coatings were homogeneous with no obvious cracks or pinholes at relatively high concentrations of both polysiloxane and BG. The cell biology experiments confirmed that the expressed cell-morphology, analyzed on chosen surfaces, was pheno-typical for MG-63 cells after 48 h of incubation. On the film containing the lower amount of polysiloxane/BG the most dense cell layer was formed. Our results indicated that polysiloxane/BG composite films exhibited good cyto-compatibility at 260 °C and 500 °C and showed no toxicity toward MG-63 cells suggesting the potential of this composite for applications in medical implants.     

Synthesis and properties of novel poly(tetramethylsilnaphthylenesiloxane) derivatives

Novel poly(tetramethylsilnaphthylenesiloxane) derivatives were synthesized and characterized by differential scanning calorimetry (DSC), thermogravimetry (TG), and X-ray diffraction analyses. Poly(tetramethylsilnaphthylenesiloxane) derivatives were obtained by condensation polymerization of the corresponding disilanol derivatives, i.e. 1,4-, 1,5-, 2,6-, and 2,7-bis(dimethylhydroxysilyl)naphthalenes, which were prepared by the Grignard reaction using chlorodimethylsilane and the corresponding dibromonaphthalene derivatives followed by the hydrolyses, catalyzed by palladium on charcoal. The obtained poly(tetramethyl-1,5-silnaphthylenesiloxane) was insoluble in common organic solvents; however, the other polymers exhibited the good solubility in common organic solvents, such as tetrahydrofuran (THF), chloroform, dichloromethane, and toluene. The introduction of tetramethyl-1,5-silnaphthylenesiloxane units into the resulting polymer was confirmed by ¹H NMR spectrum of the copolymer obtained by condensation copolymerization of 1,5-bis(dimethylhydroxysilyl)naphthalene with 1,4-bis(dimethylhydroxysilyl)naphthalene. It was revealed from the DSC and X-ray diffraction measurements that poly(tetramethyl-1,5-silnaphthylenesiloxane) and poly(tetramethyl-2,6-silnaphthylenesiloxane) exhibited the crystallinity; however, poly(tetramethyl-1,4-silnaphthylenesiloxane) and poly(tetramethyl-2,7-silnaphthylenesiloxane) were amorphous. The glass transition temperature (T_g) and the temperature at 5% weight loss (T_d5) of poly(tetramethylsilnaphthylenesiloxane) derivatives with dimethylsilyl group at 1-position of the naphthylene moiety were higher than those at 2-position of the naphthylene moiety. The T_g and melting point (T_m) of the present polymers were higher than those of poly(tetramethyl-1,4-silphenylenesiloxane).     

Linear and hyperbranched liquid crystalline polysiloxanes

A series of liquid crystalline (LC) polymers having biphenyl (-C₆H₄C₆H₄R; R=H, OC₁₁H₂₃, OC(O)CH(Cl)CH₂CH₂COOCH₂CH₃) 4-methoxyphenyl benzoate (-C₆H₄C(O)OC₆H₄OCH₃) and cholesteryl type mesogenic moieties were synthesized. They were made from respective -Si(CH₃)₂H terminated mesogens and vinyl functionalized linear and star shape branched polysiloxanes of comb-like and dendritic topologies and were analyzed using WAXS and SAXS techniques. Contrary to the well defined typical dendrimers, in which mesogenic groups are present in an outer sphere, the dendritic systems described here contain such groups also inside the dendritic core. It was found that star shape and dendritic LC structures exhibited various calamitic mesophases (SmA, N* and SmC*) depending on the type of mesogenic groups. On the contrary, the comb-like structures give rise to formation of hexagonal phase, even though they contain typical rod-like mesogenic moieties. For the series of 4-methoxyphenyl benzoate substituted polymers the thorough studies of the relationship between their liquid crystalline properties and topology of siloxane skeleton was determined. Mechanical properties of the LC materials were also studied.     

紫外光固化丙烯酸酯聚硅氧烷防粘剂

以二端羟基二甲基聚硅氧烷和γ－甲基丙烯酰氧丙基三甲基硅烷为主要原料,合成制备了具有紫外光固化性能的丙烯酸酯聚硅氧烷防粘剂预聚体,以此为基础,配制成了具有较好性能的防粘剂,还对分子质量,稀释剂等因素树防粘性能的影响进行了分析。     

Synthesis and characterization of poly(lactide-b-siloxane-b-lactide) copolymers as magnetite nanoparticle dispersants

Poly(lactide-b-siloxane-b-lactide) triblock copolymers with pendent carboxylate groups have been synthesized to serve as dispersants for magnetite nanoparticles. Magnetic nanoparticles are of interest for potential biomedical applications including magnetic field-directed drug delivery and magnetic cell separations. For in-vivo applications, it is important that the magnetic particle be coated with biocompatible organic materials to afford dispersion characteristics or to further modify the surfaces of the complexes with biospecific moieties. Synthesis of the triblock copolymer dispersants comprises three reactions. First, difunctional, controlled molecular weight, telechelic, polymethylvinylsiloxane (PMVS) oligomers with 3-aminopropyl endgroups were prepared in ring-opening redistribution reactions. Secondly, these oligomers were utilized as macroinitiators for ring-opening l-lactide or d,l-lactide to provide triblock materials with PMVS central blocks and polylactide end blocks. Both the PMVS oligomers and the poly(lactide-b-siloxane-b-lactide) copolymers had the expected molecular weights and compositions. Thirdly, the vinyl groups on the polysiloxane center were functionalized with carboxylic acids by adding mercaptoacetic acid across the pendent double bonds. At neutral pH, the carboxylate-functional polysiloxane central block binds to the surfaces of magnetite nanoparticles, while the polylactides serve as tail blocks to provide dispersibility in polylactide solvents through interparticle steric repulsive forces. Analyses confirmed that the copolymers indeed adsorbed onto the surfaces of the magnetite nanoparticles, but fractionations of these materials suggested that the composition distribution of the components was somewhat inhomogeneous.     

Synthesis and characterization of cholesteric liquid crystalline copolysiloxanes containing 4-biphenyl 4-allyloxybenzoate and [S]-1-(2-naphthyl)ethyl 6-[4-(10-undecen-1-yloxy) biphenyl-4′-carbonyloxy]-2-naphthoate side groups

A series of side-chain liquid crystalline copolysiloxanes containing 4-biphenyl 4-allyloxybenzoate and     

环氧聚硅氧烷体系开发与应用

本文论述了环氧－聚硅氧烷改性体系的种类,制备方法,性能特下及应用,并介绍了笔者所在课题组在该体系中研制空的新结果。     

Synthesis and antimicrobial activities of polysiloxane-containing quaternary ammonium salts on bacteria and phytopathogenic fungi

A series of dimethylaminopropyl benzyl chloride grafted polysiloxanes (PDMS-g-BCs) with tunable molecular weights and cationic content were synthesized, and the effect of polymer structure on the antimicrobial activities against bacteria (Escherichia coli (E. coli) and Staphylococcus albus (S. albus)) and phytopathogenic fungi (Rhizoctonia solani (R. solani) and Fusarium oxysporum f. sp. cubense race 4 (Foc4)) were systematically assessed. The antibacterial activity was evaluated by determining the minimum inhibitory concentration (MIC) against E. coli and S. albus by the broth dilution method, and the antifungal activity was measured by mycelia growth inhibition as well as by the MIC and minimum fungicidal concentration (MFC) values. The molecular weight and cationic content were major determinants of the activities of PDMS-g-BCs; when the molecular weight was approximately 2500 g/mol and the cationic content was approximately 20 mol% of the total siloxane units, PDMS-g-BCs gained strong antimicrobial activities toward both E. coli and Foc4, comparable to those of a commonly used broad-spectrum microbicide benzalkonium chloride, making PDMS-g-BCs promising fungicidal agents for plant disease control.     

聚硅氧烷接枝共聚物

本文介绍了一些聚硅氧烷的接枝共聚物。它们的合成与普通聚合物类似，接枝共聚技术可用于橡胶、塑料及无机材料的改性，经改性后聚合物溶合了两者的性能，其应用领域进一步扩展。     

碱溶性光敏有机硅聚氨酯丙烯酸酯光固化膜的性能研究

设计合成了一种碱溶性光敏有机硅聚氨酯丙烯酸酯(Alkali-soluble polysiloxane urethane acrylate,APSUA),以期用于阻焊油墨.详细研究了体系组成对APSUA体系的耐水性、体积收缩、硬度、拉伸性能及耐热性能的影响.研究发现:含羟基活性单体会使体系吸水率上升;随着体系交联度增加,...