Polymer-silica Hybrid Materials Research Articles

Functional Metalloblock Copolymers for the Preparation and In Situ Functionalization of Porous Silica Films.

Stimuli-responsive mesoporous silica films were prepared by evaporation-induced self-assembly through the physical entrapment of a functional metalloblock copolymer structuring agent, which simultaneously served to functionalize the mesopore. After end-functionalization with a silane group, the applied functional metalloblock copolymers were covalently integrated into the silica mesopore wall. In addition, they were partly degraded after the formation of the mesoporous film, which enabled the precise design of accessible mesopores. These polymer–silica hybrid materials exhibited remarkable and gating ionic permselectivity and offer the potential for highly precise pore filling design and combination with high-throughput printing techniques. This in situ functionalization strategy of mesoporous silica using responsive metalloblock copolymers has the potential to improve how we approach the design of complex architectures at the nanoscale for tailored transport. This functionalization strategy paves the way for a variety of technologies based on molecular transport in nanoscale pores, including separation, sensing, catalysis, and energy conversion.

PTurning to Nanotechnology for Water Pollution Control: Applications of Nanocomposites

A new wave of science innovation is based on something much smaller than ever before. Nanotechnology is the hottest buzz in laboratories around the world. Scientists are using this cutting edge technology not only to develop incredible new products, but also to work towards cleaning water. Recently, heavy metal contamination has develop to be the essential serious ecological issues. The treatment of heavy metals is of special concern in the environment. As of late, different techniques for removal of heavy metal ions from wastewater have been widely considered. Adsorption is a standout amongst the most simple and productive process for treating industrial effluents, and a helpful mechanism to safeguard the ecosystem. The uses of novel nano-adsorbent for the treatment of waste water are confirmed by the continuous increment in research articles publication on adsorption of heavy metal ions using organic-inorganic nanocomposites. The present article highlights the late advancements in the preparation of nano adsorbents incorporating polymer-silica hybrid materials by sol-gel technique. The primary goal of the present review is to depict the versatile nature of polymer-silica hybrid materials and their ability to absorb variety of heavy metal ions which are present in the wastewater. An endeavor is likewise being made to incorporate adequate data like the strategy for synthesis of polymer-silica hybrid materials, structure, their adsorption capacity, variables affecting the adsorption and the plausible mechanism involve in adsorption of heavy metal ions from contaminated water.

Synthesis of core-shell hydrophilic polymer-silica hybrid material and its application in N -glycan enrichment

Protein N-glycosylation is one of the most important post-translational modifications closely correlated with many important biological and pathological processes. The structural alterations of N-linked glycans in glycoproteins are always associated with many diseases, such as diabetes, heart failure and malignant tumors. Therefore, it is very important to establish sensitive methods for high-throughput N-glycan profiling. However, the low abundance of the N-glycoproteins and the heterogeneity of the N-glycans make it a challenge to analyse the protein glycosylation sensitively. In this work, we had synthesized core-shell hydrophilic polymer-silica hybrid materials (pGMAG-SiO2) for the efficient enrichment of protein N-glycans. Firstly, pGMAG-SiO2 was prepared by in situ growth of glucose polymer on the surface of silica microparticles using surface-initiated atom transfer radical polymerization (SI-ATRP) technique. The strong hydrophilicity of the material makes it suitable for the enrichment of N-glycans released from complex samples. Secondly, maltoheptaose and the N-glycans from chicken egg albumin were used as standard samples to optimize the enrichment conditions and evaluate the enrichment efficiency of pGMAG-SiO2. Finally, pGMAG-SiO2 was applied to the enrichment of N-linked glycans from human plasma proteins and 47 glycoforms were successfully identified after enrichment. These results demonstrated the high enrichment efficiency and significant application value of pGMAG-SiO2 in the analysis of N-glycans.

Porous pyridine based polyimide–silica nanocomposites with low dielectric constant

Highly porous polymer–silica hybrid materials were prepared based on the organo-soluble polyimides of four various dianhydride and 2,5-diaminopyridine. 3-Aminopropyltriethoxysilane (APS) was used to increase the intrachain chemical bonding and interchain hydrogen bonding between the polyimide and silica moieties, respectively. The chemical interaction would significantly affect the morphologies and properties of the prepared films. The produced polyimide–silica composites were investigated by X-ray diffraction analysis, scanning electron microscope and thermal analysis tecniques. The effect of silica modified with functional group of 3-aminopropyltriethoxy silane on the porous structure and dielectric properties as well as the thermal stability of films were investigated. Capacitances were determined with a HP4294A at a frequency between 1 kHz and 1 MHz. The dielectric constant was significantly reduced with increasing silica modified with APS. The result indicates that the composite materials are potentially useful in low dielectric materials.

Thermal behaviour of poly(dimethylsiloxane) hybrid silicas prepared by radiation grafting

This paper reports our investigation regarding the thermal properties of new polymer-silica hybrid materials obtained by radiation grafting. The polymer poly(dimethylsiloxane),bis(3-aminopropyl)terminated is γ-grafted on a silica gel surface. The thermal behaviour of γ-grafted hybrid materials reveals remarkable differences compared to the thermal behaviour of physically adsorbed polymers. These differences allow us to assess the ability of γ-rays to produce a polymer chemically bonded on a silica surface. The chemical bonds formed by irradiation give to the polymer a high conformational stability confirmed by DTA analysis.

Polymer–Silica Composite Materials from Octadely‐Phenylalanine‐Derivative by Surface Initiated Atom Transfer Radical Polymerization

A new monomer from octadecyl L‐phenylalanamide has been efficiently synthesized and characterized. This monomer was used to prepare polymer–silica hybrid materials by surface initiated controlled/“living” radical polymerization (CRP) method. In addition, a new surface initiated atom transfer radical polymerization (SI‐ATRP) initiator 3‐(2‐bromo‐2‐methyl) propionyloxy) allyltrichlorosilane or 3 was also prepared from allylalcohol, 2‐bromoisobutyryl bromide and trichlorosilane. ATRP polymerization of octadecyl‐phenylalanamide derived monomer has been carried out from initiator grafted mesoporous silica particles (Sil‐3). The silica‐polymer nanocomposite obtained by SI‐ATRP of N′‐dioctadecyl‐N α ‐ (methacryloyl)‐L‐phenylalanineamide (C18‐L‐Phe‐MA or 1) was characterized by DRIFT‐IR, TGA, SEM, 13C, and 29Si CP‐MAS NMR spectroscopic measurements. The characteristic data showed successful grafting of the monomer on silica surface. Moreover, unagglomerated state of the grafted particles as observed by SEM proved that this material can be effectively employed as stationary phase for high performance liquid chromatography (HPLC). The resulting chromatographic for different size and shape polycyclic aromatic hydrocarbons (PAHs) provided information that this new silica‐polymer hybrid material can be effectively used in separation science.

Preparation and properties of amino-terminated anionic waterborne-polyurethane–silica hybrid materials through a sol–gel process in the absence of an external catalyst

A series of polymer–silica hybrid materials consisting of amino-terminated anionic waterborne-polyurethane (WPU) and inorganic silica particles have been prepared through a sol–gel process in the absence of an external catalyst. Typically, amino-terminated anionic WPU was first synthesized from polycaprolactone, dimethylol propionic acid, and 4,4′-methylenebis(cyclohexyl isocyanate) with specific molar ratios, followed by further reaction with triethylamine and triethylene tetramine to give as-prepared WPU. The WPU obtained was characterized by FTIR spectroscopy and gel permeation chromatography. Subsequently, a series of hybrid materials with different silica contents were prepared by performing sol–gel reactions with tetraethyl orthosilicate (TEOS) in an amino-terminated WPU matrix without the addition of an external catalyst. This was followed by examination by transmission electron microscopy and 29Si solid-state NMR. The terminated primary amine groups attached to the as-prepared WPU chains functioned as an internal base catalyst for the sol–gel process of TEOS. The effect of composition on the thermal stability, mechanical strength, surface wettability, and optical clarity of the hybrid materials was evaluated by the thermogravimetric analysis, dynamic mechanical analysis, contact angle measurement, and UV–visible transmission spectroscopy, respectively.

Preparation and properties of waterborne dual curable monomers and cured hybrid polymers for ink-jet applications

Linear and star-like waterborne UV/moisture curable monomers with surface activity were synthesized by introducing different amounts of trimethoxysilane and methacrylate units into the monomer chains. The surface morphology, transparency and thermal properties of the cured hybrid polymer were found to be determined by the monomer structure, solvent, the amount and arrangement of trimethoxysilane groups. The polymer–silica hybrid materials crosslinked with both UV curing and sol–gel reaction exhibited good thermal properties at elevated temperature. Due to the surface activity of monomers in aqueous medium, aggregates on the film made by water diluted monomers are larger than those prepared by solvent diluted monomers. Larger aggregates lead to lower transparency. Hybrid films made by star-like monomer had smaller silica aggregates than those prepared by the linear monomers. Star-like monomer exhibited excellent compatibility with water-based pigment dispersion and good ink-jet printing properties. It can be used to improve the properties of the ink-jet printed micropatterns.

Synthesis and properties of new polyimide–silica hybrid films through both intrachain and interchain bonding

In this study, the new polymer–silica hybrid materials were prepared based on the organo-soluble polyimides of 4,4′-hexafluoroisopropylidenediphthalic anhydride (6FDA) and four diamines. 3-Aminopropyl trimethoxysilane (APrTEOS) and γ-glycidyloxypropyltrimethoxysilanes (GOTMS) were used to increase the intrachain chemical bonding and interchain hydrogen bonding between the polyimide and silica moieties, respectively. The chemical interaction would significantly affect the morphologies and properties of the prepared films. Highly homogeneous hybrid thin films were obtained according to the studies of atomic force microscopy and TEM. The silica size observed by the TEM picture was smaller than 5 nm. The thermal properties of the organo-soluble polyimides were significantly enhanced by hybridizing only 6.30–7.99 wt% of silica. The intrachain chemical bonding could effectively enhance the coefficient of thermal expansion in comparison with the interchain interaction. Low dielectric constants in the range of 2.85–3.73 were obtained for the prepared hybrid films. The refractive indices of the prepared materials could be tuned through the polyimide structure or the silica content. The optical losses of the planar waveguides based on the prepared polyimides and their hybrids at 1310 nm were in the range of 0.5–2.7 dB/cm, which were mostly due to the higher harmonics of the aromatic C–H vibration and the extrinsic loss. The prepared polyimide–silica hybrid materials could have potential applications for microelectronics or optical communications.

Polymer-silica hybrid materials prepared from some functionalized polybenzoxazoles and polybenzobisthiazoles

Hybrid organic-inorganic composites were prepared by precipitating silica into hydroxypolybenzoxazole (HPBO) and sulfopolybenzobisthiazole (SPBT) polymers, with interfacial bonding between the phases improved by use of isocyanatopropyltriethoxy silane and N, N-diethylaminopropyltrimethoxy silane, respectively. The materials were transparent, and scanning electron micrographs indicated a uniform distribution of silica particles of domain sizes less than 1 μm. Values of the tensile modulus and tensile strength of the HPBO-silica composites were found to increase with the silica content. Values of the modulus of the SPBT-silica composites also increased in this manner, but the improvements in tensile strength were nearly independent of the amount of silica. The composites exhibited thermal decomposition temperatures of approximately 400–500°C, and the thermal stability was significantly increased for both HPBO and SPBT materials with increase in silica content. The water absorption amount for both types of composites decreased significantly compared to that of the pure polymers, suggesting excellent weatherability.