Study of the effects of melt blending speed on the structure and properties of phosphate glass/polyamide 12 hybrid materials

The effects of melt blending conditions on the rheology, crystallization kinetics, and tensile properties of phosphate glass/polyamide 12 hybrid systems were investigated for the first time, to understand their complex processing/structure/property relationships. Increasing amounts of phosphate glass (Pglass) caused an increase in hybrid viscosity. Hybrid viscosity was also affected by processing (melt‐mixing) speed and small‐amplitude oscillatory shear tests and scanning electron microscopy (SEM) were used for a qualitative examination of the hybrid morphology. The addition of Pglass caused a decrease in hybrid crystallinity that was unaffected by processing (melt‐mixing) speed. The two‐parameter Avrami equation was applied successfully to the hybrid systems, and Pglass was found to nucleate the growth of polyamide 12 crystals. The nucleation effect was found to be dependent on concentration and processing history. The tensile properties of the hybrids were also studied, and the Halpin–Tsai equation was applied to the results to determine the maximum packing fraction of the Pglass. These results provide a basis for the prediction of hybrid mechanical properties for different Pglass concentrations and processing histories. Further, because of their facile processibility and desirable characteristics, such as the strong physicochemical interaction between the hybrid components and favorable viscoelasticity, these Pglass/polyamide 12 hybrids can be used as model systems for exploring feasibility of new routes for driving organic polymers and inorganic Pglass to self‐assemble into useful organic/inorganic hybrid materials. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Glass‐polymer melt hybrids. I: Viscoelastic properties of novel affordable organic‐inorganic polymer hybrids

A novel class of organic‐inorganic polymer hybrids was developed by melt‐blending up to 50 (v/v) % [about 83 (w/w) %] tin‐based polyphosphate glass (Pglass) and low‐density polyethylene (LDPE) in conventional plastics processing equipment. The liquid‐ and solid‐state rheology of the polymer hybrids was studied under oscillatory shear flow and deformation to understand the behavior of these materials and to accelerate efforts to melt process the Pglass with organic polymers. All the materials were found to be linearly viscoelastic in the range of temperature and frequencies examined and their viscoelastic functions increased with increasing Pglass concentration. The Pglass significantly enhanced the shear‐thinning characteristics of the Pglass‐LDPE hybrid, indicating the presence of nonlinear chemical and physical interactions between the hybrid components. Morphological examination of the materials by scanning electron microscopy revealed interesting evolution of microstructure of the Pglass phase from droplets (or round beads) to elongated and interpenetrating network structures as the glass concentration was increased in the Pglass‐LDPE hybrids. Melt viscosities of the materials were well described by a simple power‐law equation and a Maxwellian (Hookean) model with three relaxation times. Time‐temperature superpositioning (TTS) of the complex viscosity versus frequency data was excellent at 170°C < T < 220°C and the temperature dependencies of the shift factors conformed excellently well to predictions from an Arrhenius‐type relation, enabling calculation of the flow‐activation energies (25–285 kj/mol) for the materials. The beneficial function of the Pglass in the hybrid system was significantly enhanced by pre‐treating the glass with coupling agents prior to incorporating them into the Pglass‐LDPE hybrids.     

Investigation of phase behavior during melt processing of novel inorganic‐organic polymer hybrid material

The phase behavior of novel, binary organic‐inorganic hybrids consisting of an ultra‐low T_g tin‐based phosphate glass (Pglass) and polystyrene (PS) was investigated. Dynamic mechanical analysis (DMA) revealed that the glass transition peaks of the PS changed slightly with Pglass volume fraction, leading to a broad peak at the phase inversion point. The phase inversion and degree of phase continuity of the hybrid were studied through solvent extraction, optical/scanning electron microscopy, and dynamic rheology. The Jordhamo and Utracki viscosity ratio models provided reliable estimates of the inversion point. Torque rheometry revealed a trend toward linear additivity within the temperature range 200°C–230°C. Small‐angle neutron scattering experiments gave further evidence of the hybrid phase incompatibility. The results of this study point to a promising new class of blend materials with the potential to present a unique combination of properties impossible to achieve with classical polymer blends. Polym. Eng. Sci. 44:1692–1701, 2004. © 2004 Society of Plastics Engineers.     

Unusual accelerated molecular relaxations of a tin fluorophosphate glass/polyamide 6 hybrid studied by broadband dielectric spectroscopy

Phosphate glass (Pglass)/polymer hybrids are a relatively new class of materials that combine the advantages of classical polymer blends and composites without their disadvantages. In the case of highly interacting Pglass/polymer (i.e., polyamide 6) hybrids, counter-intuitive properties that are difficult to explain are often observed. To shed light into the origins of the special behavior of the hybrids, we investigated the molecular relaxation processes in the hybrids using broadband dielectric spectroscopy. The dielectric loss spectra were fitted with the Havriliak-Negami equation and the characteristic relaxation times of the hybrid and the pure components were observed. The temperature dependence of the characteristic relaxation times was described using either the Vogel-Fulcher-Tammann, for the α-relaxations, or an Arrhenius type equation, for the β- and γ-relaxations. The addition of Pglass greatly accelerated both the α- and β-relaxations of the polyamide 6. However, the γ-relaxation was found to be independent of Pglass composition. This suggests partial miscibility in the solid state, which was confirmed via NMR spectroscopy. The unexpected dramatic change in the β-relaxation process in the 10 vol.% Pglass hybrid suggests that blending can change the local environment of polyamide 6 due to the nanoscale morphology of this system as confirmed by TEM and NMR. It is thought that the fraction of miscible Pglass disrupts the hydrogen bonding between polyamide 6 chains and thereby reduces coordinated, multiple chain motion. In turn, this produces a plasticization effect and possible modification of the polyamide 6's crystalline structure in the Pglass/polyamide 6 hybrids.     

Creep and recovery behavior of novel organic‐inorganic polymer hybrids

A novel class of organic‐inorganic polymer hybrids were developed by meltblending up to 50 (v/v) % [about 83 (w/w) %] tin‐based polyphosphate glass (Pglass) and low‐density polyethylene (LDPE) in conventional plastics processing equipment. The creep and recovery behavior of these polymer hybrids at 30°C were studied to understand the effect of the Pglass on the creep resistance of the LDPE. The results suggest that the Pglass acts as a reinforcement and an increase in the Pglass loading leads to significantly lower creep strains. This creep resistance is further enhanced by pretreating the Pglass with coupling agents prior to incorporating them into the Pglass‐LDPE hybrids. The experimental creep compliance of these materials conformed excellently with empirical power‐law equation and a modified Burger's model, suggesting that the materials are linearly viscoelastic under the test conditions.     

Crystallization kinetics of low‐density polyethylene and polypropylene melt‐blended with a low‐Tg tin‐based phosphate glass

The nonisothermal and isothermal crystallizations of low‐density polyethylene (LDPE) and polypropylene (PP) in phosphate glass (Pglass)–polymer hybrid blends were studied through differential scanning calorimetry (DSC). As the Pglass volume fraction was increased, the percentage crystallinity decreased. The half‐time for crystallization decreased as the propagation rate constant rose, for both of the polymer matrices, with increasing Pglass concentrations. The Pglass was observed to be a nucleating agent for formation of two‐ or three‐dimensional spherulites in the hybrids. Tensile modulus improved for both of the Pglass–polymer hybrids up to 40% Pglass, but the energy to break decreased. Tensile strength changed slightly with the addition of Pglass to the LDPE matrix, exhibiting a larger value than that of pure LDPE at 30%. The tensile strength decreased as more Pglass was added to the PP matrix. The observed differences between tensile properties of the Pglass–PP and Pglass–LDPE hybrids at identical Pglass volume concentration were found to be consistent with that of the crystallization behavior of the hybrids. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3445–3456, 2003     

有机杂化阻尼材料动态力学性能的影响因素探讨

高分子阻尼材料作为一类环保功能材料,将向高性能、宽温域的方向发展。传统的阻尼改性方法(如共混、共聚、无机杂化等)及近年来发展起来的互穿聚合物网络和添加压电陶瓷等研究手段都存在一定的局限性。新近开发的利用有机小分子与极性高聚物形成杂化体的方法所得到的阻尼材料的性能非常突出,是一种很有前途的阻尼改性新方法。本文在对现有的二元、三元杂化体系进行分析对比的基础上,对影响有机杂化阻尼材料动态力学性能的因素进行了探讨,为今后该领域的研究工作提供参考。     

Sol–gel derived organic/inorganic hybrid gels based on poly(2-hydroxyethyl aspartamide) and silica

The sol–gel derived polymer/silicate hybrid materials have attracted considerable attention in recent years. The incorporation of silicate phase into polymeric materials may constitute an important tool to either enhance mechanical properties or provide more biocompatibility to the resulting hybrids. PHEA, α,β-poly(N-2-hydroxyethyl-dl-aspartamide), is a class of poly(amino acid)s that has been widely studied as a biodegradable functional polymer with potential biomedical and pharmaceutical applications. Hydrogels from PHEA are formed easily by a chemical or physical crosslinking reaction but the resulting gels are mechanically weak and less thermally stable. In this study, hybrid materials were prepared based on PHEA and silicate. A sol–gel process was employed using TEOS and modified PHEA to introduce inorganic silicate phase within the polymer gel matrix. FT-IR and NMR were used to analyze the chemical structure of the PHEA derivatives. In addition, the morphology, thermal and swelling properties of the hybrid gels were examined.     

Biaxially oriented poly(propylene-g-maleic anhydride)/phosphate glass composite films for high gas barrier applications

The solid state structure and oxygen transport properties of biaxially oriented poly(propylene-graft-maleic anhydride) (PPgMA) reinforced with a low glass transition temperature (T_g) phosphate glass (Pglass) were investigated. Composites were prepared by melt blending PPgMA with up to 20 volume% Pglass. Melt blended composites were compression molded into monolayer structures and then biaxially stretched at a temperature above the T_g of the Pglass. Scanning electron microscopy confirmed that biaxial stretching transformed the spherical Pglass particles into platelets oriented in the plane of the film. Gas transport measurements revealed a reduction in the oxygen permeability by as much as 2 orders of magnitude compared to the unoriented PPgMA film. The permeability was analyzed according to performance models for dispersions of platelet-like fillers proposed by Cussler and Nielson. Aspect ratios ranging from 15 to 80 were obtained by fitting the experimental data to the models. Mechanical tests revealed that blending with Pglass increased the modulus of the stretched film but reduced the elongation at break only slightly.     

Synthesis and characterization of poly(vinyl alcohol)/water glass (SiO2) nano‐hybrids via sol‐gel process

A new class of materials based on inorganic and organic species combined at a nanoscale level has received large attention recently. In this work the idea of producing hybrid materials with controllable properties is applied to obtain foams to be used as catalyst supporting. Hybrids were synthesized by reacting poly(vinyl alcohol) in acidic solution with water glass. The inorganic phase was also modified by incorporating a hexamethyldisiloxane as precursor. The hybrid aerogel powder was analyzed by scanning electron microscopy, TG‐DTA, Nitrogen adsorption–desorption, X‐ray diffraction and fourier transform infrared spectroscopy (FTIR) spectroscopy. The powder obtained had a higher porosity varying from 65 to 90% and the nanopore diameter ranged from 17 to 20 nm. The surface area and nanopore volume decreased as polymer content increased in the hybrids. The sharp decline in the weight observed at around 500°C accompanied an exothermic peak of the DTA curve. The sharp peak was observed around 211°C represents the DTA curve of Poly vinyl alcohol constituent in nano hybrids. The peak at 1638 cm^?1 in the FTIR indicated the formation of Si? O? PVA? O? Si bridge in aerogel powder. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Polyoxometalate/polymer hybrid materials: fabrication and properties

In this article we provide an overview of the fabrication and properties of polyoxometalate/polymer hybrid materials. Physical blending, electrostatic adsorption, covalent bonding and supramolecular modification are the main strategies to incorporate polyoxometalates into organic or inorganic (taking silica as an example) polymer matrices. The polyoxometalate/polymer hybrid materials obtained concurrently possess the unique optical, electrical or catalytic properties of polyoxometalates and the favorable processability and stability of polymer matrices. Polyoxometalate/polymer hybrid materials may have potential applications in optics, electronics, biology, medicine and catalysis. Copyright © 2009 Society of Chemical Industry     

Bicontinuous porosity in ceramics utilizing polymer spinodal phase separation

This paper demonstrates how the combination of inorganic and organic polymers can be used to form bicontinuous porosity in ceramics with pore sizes larger than 5 μm. Spinodal phase separation of pseudo-binary polymer mixtures allows to form larger bicontinuous pore structures than spinodal phase separation of inorganic glasses. Addition of salts allows even more complex compositions of ceramics and glasses to be formed. Here, bioactive glasses are presented that were produced via sol–gel processing of a pseudo-binary mixture of an inorganic and an organic polymer. Due to the addition of an organic polymer to the gelling sol and the spinodal phase separation at a specific equilibrium temperature, both an inorganic polymer ceramic phase and organic polymer-rich phase are formed. The evaporation of the solvent and the burnout of the organic polymer produce a microstructure of interconnected and nearly uniform porosity, which can be controlled by several processing parameters. The dependency of pore size and connectivity is best predicted by polymer phase separation rather than glass melt separation. Results suggest that polymer spinodal phase separation could be useful for the manufacture of a variety of porous ceramics.     

Mechanical properties of functionalized SEBS based inorganic hybrid materials

Summary Functional triblock copolymer [polystyrene-b-poly(ethylene-ran-butylene)-b-polystyrene] or SEBS elastomer was used to synthesize flexible organic-inorganic hybrid materials. Modification of elastomer was first achieved via nitration to produce nitrofunctionalized copolymer and its subsequent reduction forming aminofunctionalized copolymer. IR, ¹H NMR and ¹³C NMR spectroscopic analyses provided an evidence of their modified structures. Modified SEBS based hybrid materials were then prepared through solution intercalation technique using layered silicates and in-situ polymerization of metal alkoxides via sol-gel process. In the first attempt, hybrids were prepared by the reinforcement of aminofunctionalized SEBS with organophilic montmorillonite to establish compatibility between organic matrix and inorganic phase. Reinforcement of the modified copolymer was secondly achieved by hydrolytic condensation of tetraethoxysilane using 3-glycidyloxypropyl trimethoxysilane (as a coupling agent) yielding hybrid materials. The chemical interactions between the organic polymer chains and the inorganic networks produced in-situ led to better properties of modified elastomer. Mechanical properties of thin transparent films of these hybrids were measured. Tensile strength of hybrids shows a considerable improvement over pure SEBS as well as aminofunctionalized copolymer in all the systems, which shows an increased interfacial interaction between organic and inorganic phases.     

Study on acrylic resin/titania organic-inorganic hybrid materials prepared by the sol-gel process

Acrylic resin/titania organic-inorganic hybrid materials were prepared by the two approaches. One approach (BL method) was blending titania produced by the sol-gel process with synthesized acrylic resins containing various content of acrylic acid (AA). Another approach (IS method) was the in situ polymerization of acrylic monomers in synthesized titania sols. The structure and mechanical, thermal and optical properties of the hybrid films were investigated by small angle X-ray scattering (SAXS), atomic force microscopy (AFM), dynamic mechanical analysis (DMA), Instron testing machine, thermogravimetric analysis (TGA) and ultraviolet-visible spectroscopy (UV-VIS), respectively. Titania phase in the hybrids showed an open structure and nano-scale size. However, aggregation of titania occurred in the systems prepared by IS method or without AA contained. The mechanical properties, thermal stability and UV shielding properties of organic polymer were obviously improved with titania networks embedded. It was found that BL method could prepare homogeneous hybrids with better integrative mechanical properties in comparison with IS method.     

聚合物阻尼材料的分子设计与复合改性

介绍了聚合物阻尼材料的分子设计;论述了共聚物的分子设计、阻尼微结构、梯度阻尼结构等;综述了聚合物阻尼材料复合改性的研究进展。对共混及互穿聚合物网络、有机／无机杂化体系、纳米复合体系和聚合物／小分子复合体系等进行了述评。     

An experimental study of morphology and rheology of ternary Pglass‐PS‐LDPE hybrids

Ternary blends of low‐density polyethylene (LDPE), polystyrene (PS), and a low T_g tin‐based phosphate glass (Pglass) were prepared at compositions ranging from 0–50 vol% Pglass in which either LDPE or PS was the continuous matrix phase. Differential scanning calorimetry was used to investigate the phase behavior of the pure components, PS‐LDPE blends and binary Pglass‐polymer hybrids. Interesting steady‐shear and transient rheology was observed for the hybrids. In particular, the steady shear viscosity curves for the hybrids of ?_Pglass ≤ 30% exhibited unusual, four‐region flow behavior, similar to that of liquid crystalline polymers. Two Newtonian plateaus at low (${\rm \dot \gamma }$ ≤ 0.1 s^?1) and moderate (0.4 ≤ ${\rm \dot \gamma }$ ≤ s^?1) shear rates connected by two distinct shear‐thinning regimes were apparent. This observed rheology is ascribed to a unique composite morphology of these multi‐component systems. Rheological data on the binary Pglass‐polymer systems suggest that the presence of the Pglass within both PS and LDSE contributes significantly to this unusual behavior, perhaps because of the interfacial behavior between the phases. Micrographs obtained via scanning electron microscopy reveal preferential placement of the Pglass phase dispersed within the PS‐phase and surrounding the LDPE phase. Optical shearing data confirmed the evolution of this microstructure under specific shear conditions.     

Synthesis and proton conducting properties of zirconia bridged hydrocarbon/phosphotungstic acid hybrid materials

Recently, the organic/inorganic hybrid materials with flexibility, thermal, and chemical stabilities are extensively studied for the application of temperature tolerant polymer electrolyte fuel cells. This paper reports the preparation and properties of sol-gel derived proton conducting organic/inorganic materials based on zirconia bridged hydrocarbon phosphotungstic acids. The materials are molecular hybrids where linear hydrocarbons such as trimethylene glycols (TMGs) or octamethylene glycols (OMGs) are covalently bonded to zirconia interface to form macromolecular organic/inorganic networks. The hybrid materials become proton conducting polymer electrolytes by the addition of 12-phosphotungstic acids. The hybrid materials showed high thermal stability, and high protonic conductivity of 4×10⁻³ S cm⁻¹ under saturated humidity condition at 150 °C. The materials can be expected to be used for the application of temperature tolerant polymer electrolyte fuel cell.     

DNA block copolymers: functional materials for nanoscience and biomedicine

We live in a world full of synthetic materials, and the development of new technologies builds on the design and synthesis of new chemical structures, such as polymers. Synthetic macromolecules have changed the world and currently play a major role in all aspects of daily life. Due to their tailorable properties, these materials have fueled the invention of new techniques and goods, from the yogurt cup to the car seat belts. To fulfill the requirements of modern life, polymers and their composites have become increasingly complex. One strategy for altering polymer properties is to combine different polymer segments within one polymer, known as block copolymers. The microphase separation of the individual polymer components and the resulting formation of well defined nanosized domains provide a broad range of new materials with various properties. Block copolymers facilitated the development of innovative concepts in the fields of drug delivery, nanomedicine, organic electronics, and nanoscience. Block copolymers consist exclusively of organic polymers, but researchers are increasingly interested in materials that combine synthetic materials and biomacromolecules. Although many researchers have explored the combination of proteins with organic polymers, far fewer investigations have explored nucleic acid/polymer hybrids, known as DNA block copolymers (DBCs). DNA as a polymer block provides several advantages over other biopolymers. The availability of automated synthesis offers DNA segments with nucleotide precision, which facilitates the fabrication of hybrid materials with monodisperse biopolymer blocks. The directed functionalization of modified single-stranded DNA by Watson-Crick base-pairing is another key feature of DNA block copolymers. Furthermore, the appropriate selection of DNA sequence and organic polymer gives control over the material properties and their self-assembly into supramolecular structures. The introduction of a hydrophobic polymer into DBCs in aqueous solution leads to amphiphilic micellar structures with a hydrophobic polymer core and a DNA corona. In this Account, we discuss selected examples of recent developments in the synthesis, structure manipulation and applications of DBCs. We present achievements in synthesis of DBCs and their amplification based on molecular biology techniques. We also focus on concepts involving supramolecular assemblies and the change of morphological properties by mild stimuli. Finally, we discuss future applications of DBCs. DBC micelles have served as drug-delivery vehicles, as scaffolds for chemical reactions, and as templates for the self-assembly of virus capsids. In nanoelectronics, DNA polymer hybrids can facilitate size selection and directed deposition of single-walled carbon nanotubes in field effect transistor (FET) devices.     

Relation between the scratch resistance and the chemical structure of organic–inorganic hybrid coatings

Organic–inorganic hybrid materials can be defined as materials combining organic and inorganic domains in a nanometric scale. The development of these organic–inorganic hybrids has achieved properties from both organic and inorganic materials.     

ATRP技术在新型高分子材料合成中的应用

原子转移自由基聚合（ATRP）是用来设计一系列指定和拓朴结构和功能化聚合珠材料的一种用途广泛、简单易行、有工业前景的聚合技术。它适用于乙烯类单体在水相或有机相中合成梯形、嵌段、接枝、梳型、树枝状、星型以及有机／无机杂化材料。