Modification of porous silica particles with poly(acrylic acid)

The surface of porous silica particles was modified with poly(acrylic acid) by reacting the carboxyl groups on poly(acrylic acid) with the amino groups of pregrafted aminopropyltriethoxysilane (APS). The chemical modifications by APS and polymer were characterized by infrared spectroscopy and the amount of APS and poly(acrylic acid) grafted to the surface were determined by thermal gravimetric analyses. The wettability of the modified silica particles, based on the rate of water penetration, was pH‐dependent with PAA; at pH 1.5 the wettability increased but at pH 5.5 it decreased dramatically. The pore size and size distribution of the silica particles decreased with APS and polymer grafting. Copyright © 2000 John Wiley & Sons, Ltd.     

An effective cross-linking of polymer layer on monodisperse, poly(maleic anhydride-styrene)-modified colloidal silica particles and properties of the composite

Summary  The cross-linkings of the surface polymer layer on mono disperse, poly(maleic anhydride-styrene)-modified silica particles by the reaction with diisocyanate were studied. The extent of cross-linking was estimated by the weight decrease by immersing the particles in the buffer solution of pH 2.0, 4.0 and 9.0 at a room temperature for 24 h. The reaction of the polymer-modified silica with 1,6-diisocyanatohexane afforded relatively stable composite particles which lost less than 5 wt% of the polymer in aqueous solution in the pH range 2.0–9.0. The diisocyanate was a preferable cross-linker to 2,4-diisocyanatotoluene in terms of stability in acidic or basic aqueous solution. The flexibility of the cross-linker molecule possibly plays an important role in the cross-linking reaction. The carboxyl and amino groups were formed by treating the cross-linked composite particles with diluted HCl solution; 5–6 and 0.5–1.1 μmol g^-1, respectively. The cross-linked composite particles exhibited the characteristic property of ζ-potential, −44 to −47 mV and −102 to −107 mV in a neutral aqueous solution and ethanol, respectively. Received: 26 May 1997 Accepted: 4 August 1997     

环氧树脂增韧改性的研究进展

概述了近年来互穿聚合物网络（IPN）、刚性粒子增韧环氧树脂的研究现状,并展望了环氧树脂增韧改性研究的前景。     

Telechelic,Antimicrobial Hydrophilic Polycations with Two Modes of Action

Telechelic antimicrobial poly(2‐oxazoline)s with quaternary ammonium (quat) end groups are shown to be potent antimicrobial polymers against Gram‐positive bacterial strains. In this study, the activity against the Gram‐negative bacterium Escherichia coli is additionally implemented by hydrolyzing the poly(2‐methyl‐2‐oxazoline) with two quart end groups to poly(ethylene imine) (PEI). The resulting telechelic polycations are active against Staphylococcus aureus and E. coli. The contribution of the PEI backbone is determined by measuring the antimicrobial activity in the presence of calcium ions. The influence of PEI on the overall activity strongly depends on the molecular weight and increases with higher mass. The PEI dominates the activity against E. coli at lower masses than against S. aureus. The quart end groups require an alkyl substituent of dodecyl or longer to dominate the antimicrobial activity. Additionally, PEI and quart end groups act synergistically.     

Polyurethane (urea)/polyacrylates interpenetrating polymer network (IPN) adhesives for low surface energy materials

On the basis of the polymerization of the acrylate phase catalyzed by the oxidation of trialkylborane at room temperature, a series of polyurethane (urea)/polyacrylates adhesives with interpenetrating polymer network structure (IPNS) was synthesized. The crosslinking polyurethane (urea) phase was synthesized by the reaction between polymer diamine or triol and isocyanate. The resulting IPN adhesives as a function of the polyurethane (urea) or 2‐hydroxylethyl acrylate terminated polyurethane (HEA‐PU) (crosslinking agent of acrylate phase) content were explored. The adhesive morphology took on the IPNS that manifested as a finely dispersed polyurethane (urea) phase in the acrylate phase. Excellent adhesion to low surface energy materials was achieved within a wide range of polyurethane (urea) contents. The IPN adhesives also displayed better flexibility than polyacrylate adhesives with HEA‐PU as a crosslinking agent. Copyright © 2011 John Wiley & Sons, Ltd.     

Ion-imprinted interpenetrating network gels for solid-phase extraction of heavy metal ions

In the present work, ion-imprinted interpenetrating polymer network (IPN) gels were prepared by free radical/cationic hybrid polymerisation of acrylamide (AAm) and 1,4-butanediol vinyl ether (BVE). These gels were respectively used for separation of Cu²⁺, Ni²⁺ and Zn²⁺ ions in natural water samples. Experimental conditions for effective adsorption of metal ions were optimised with respect to different experimental parameters by column procedures in detail. The optimum pH value for the adsorption of Cu²⁺, Ni²⁺ and Zn²⁺ ions on these sorbents was 6.0. Complete elution of the adsorbed metal ions from the sorbent was carried out using 1.0 mol/L of HCl solution. The optimum sample flow rate and eluent flow rate were, respectively, 1.0 and 0.3 mL/min. Common coexisting ions did not interfere with the separation and determination of the target ions. The accuracy of the proposed method was validated by analysis of the standard reference material (GBW 08301, river sediment). The measured contents of metal ions in the reference material were in good agreement with the certified values. The presented method was successfully applied for the determination of Cu²⁺, Ni²⁺ and Zn²⁺ ions in three different water samples (well water, seawater and waste water).     

Synthesis of monodispersed molecularly imprinted polymer particles for high-performance liquid chromatographic separation of cholesterol using templating polymerization in porous silica gel bound with cholesterol molecules on its surface

Monodispersed molecularly imprinted polymer particles selective for cholesterol were prepared by the copolymerization of styrene and divinylbenzene in the presence of template silica gel particles (particle size: 5 μm; pore size: 10 nm) functionalized with cholesterol on the surface, followed by dissolution of the cholesterol-bonded silica gel with a NaOH aqueous solution. Transmission and scanning electron micrographs of the molecularly imprinted polymer (MIP) particles revealed good monodispersity and porous structure. The MIP particles were packed into a high performance liquid chromatographic column, and its recognition ability of cholesterol was evaluated using cholesterol, cholesterol esters and fatty acid methyl esters by comparison with the non-imprinted polymer (NIP) particles prepared from styrene and divinylbenzene without cholesterol. The MIP particles showed a high affinity for cholesterol and cholesterol esters (K(MIP)'/K(NIP)' > 5.7).     

互穿网络高吸水树脂IPN的合成

采用溶液聚合制备了聚乙烯醇(PVA)和部分中和的丙烯酸-丙烯酰胺共聚物复合的互穿网络高吸水树脂(IPN)。通过正交实验研究了单体浓度,交联剂用量对IPN吸水率的影响。PVA的加入能有效提高IPN的吸水能力。在较适宜的反应条件下,IPN吸蒸馏水量达1481倍,吸0.9%NaCl溶液为130倍。     

sol-gel 法在有机-无机杂化体系中制备二氧化硅微粒

利用sol-gel法,通过正硅酸乙酯（tetraethyl orthosilicate（TEOS））在聚氧化乙烯／二甲基甲酰胺溶液中水解、缩聚,制备了粒径分布均匀的微米级二氧化硅粒子;利用扫描电子显微镜观测了制备条件对二氧化硅粒子的粒度和形貌的影响;研究了这一方法在制备无机粒子过程中的原理．     

Enhanced properties of poly(lactic acid) with silica nanoparticles

The objective of this article is to fabricate poly(lactic acid) (PLA) and nano silica (SiO₂) composites and investigate effect of SiO₂ on the properties of PLA composites. Surface‐grafting modification was used in this study by grafting 3‐Glycidoxypropyltrimethoxysilane (KH‐560) onto the surface of silica nanoparticles. The surface‐grafting reaction was confirmed by Fourier transform infrared spectroscopy and thermogravimetric analysis. Then the hydrophilic silica nanoparticles became hydrophobic and dispersed homogeneously in PLA matrix. Scanning electron microscope and Dynamic thermomechanical analysis (DMA) results revealed that the compatibility between PLA and SiO₂ was improved. Differential scanning calorimetry and polarized optical microscope tests showed that nano‐silica had a good effect on crystallization of PLA. The transparency analysis showed an increase in transparency of PLA, which had great benefit for the application of PLA. The thermal stability, fire resistance, and mechanical properties were also enhanced because of the addition of nano silica particles. Copyright © 2016 John Wiley & Sons, Ltd.     

Influence of the bulk and surface morphology on adhesion of polystyrene-inter-poly-cross-2-ethylhexyl-methacrylate films and particles

The adhesion behavior of semi-interpenetrating polymer networks (semi-IPNs) of linear polystyrene (PS) in crosslinked poly-2-ethylhexylmethacrylate (EHMA) was studied by variation of the bulk and surface morphology, i.e., domain size, continuity, and concentration in the domains. Semi-IPNs were prepared by liquid-liquid demixing upon cooling of a homogeneous solution of PS in methacrylate monomer, followed by gelation of the PS-rich phase and UV polymerization of the methacrylate resin. Welding of films allowed the preparation of larger objects provided that (1) the samples were phase separated to a high degree and contained domains with a high PS concentration (>90%) and (2) polystyrene was present at the interface. For semi-IPN films, a linear dependence of the adhesion strength on the (crack healing time)^1/4 was obtained. Based on these considerations, a process was developed to obtain melt-processable semi-IPN particles, by quenching droplets of the polymer solution into a cold liquid. These particles obtained a PS-rich skin layer and showed good adhesion after blending with a thermoplast. © 1996 John Wiley & Sons, Inc.     

Synthesis of poly(vinylidene fluoride) (PVdF)/silica hybrids having interpenetrating polymer network structure by using crystallization between PVdF chains

High transparent and homogeneous poly(vinylidene fluoride) (PVdF)/silica hybrids were obtained by using an in‐situ interpenetrating polymer network (IPN) method. The simultaneous formation of PVdF gel resulting from the physical cross‐linking and silica gel from sol–gel process prevented the aggregation of PVdF in silica gel matrix. To form the physical cross‐linking between PVdF chains, the cosolvent system of dimethylformaide (DMF) and γ‐butyrolactone was used. The obtained PVdF/silica hybrids had an entangled combination of physical PVdF gel and silica gel, which was called a “complete‐ IPN” structure. The physical cross‐linking between PVdF chains in silica gel matrix was confirmed by differential scanning calorimetry (DSC) measurements. The miscibility between PVdF and silica phase was examined by scanning electron microscopy (SEM) and tapping mode atomic force microscopy (TM‐AFM) measurements. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3543–3550, 2005     

Antimicrobial activities of polymeric quaternary ammonium salts from poly(glycidyl methacrylate)s

Amino poly(glycerol methacrylate)s (PGOHMAs) were synthesized from linear and 8‐arm poly(glycidyl methacrylate)s (PGMAs) via ring opening reactions with methylethylamine (MEA), diethylamine, and dipropylamine, respectively, which were further modified by quaternization reaction using methyl iodide to obtain quaternized PGMAs (QPGMAs for short). The products were characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, gel permeation chromatography, and thermogravimetric analysis. The amination percentage of amino PGOHMAs and the degree of quaternization of QPGMAs were calculated by elemental analysis and X‐ray photoelectron spectroscopy, respectively. According to the solubility test results, 8‐arm PGOHMA modified with MEA (S8‐MEA) is the only water‐soluble derivative of amino PGOHMAs and was employed as a positive control for the comparison with QPGMAs. Antimicrobial studies on these PGMA derivatives were carried out by testing the minimum inhibitory concentration and the bacteria inhibitive rate against Escherichia coli and Staphylococcus aureus. The results indicated that QPGMAs possessed higher antimicrobial activity than S8‐MEA and exhibited increased antimicrobial activity against both bacteria with an increased degree of quaternization in weak basic conditions. Moreover, the chemical structure of PGMA derivatives and pH value of the assay conditions were found to affect the antimicrobial activity. Copyright © 2013 John Wiley & Sons, Ltd.     

聚苯乙烯/聚丙烯酸丁酯乳胶互穿聚合物网络的动态力学性能研究

<正> 互穿聚合物网络(IPN)是一种新型聚合物共混物.自Sperling在1969年合成聚丙烯酸乙酯/聚苯乙烯异步IPN(Sequential IPN)后,该领域进展很快.乳胶IPN(latex IPN)是用改进的乳液聚合法合成的一种微观互穿IPN.在前文中,我们报道了聚苯乙烯/聚丙烯酸丁酯(PS/PBA)乳胶IPN的合成,本文研究一些因素对PS/PBA乳胶IPN动态力学性能的影响.     

Hydrophilic silicone hydrogels with interpenetrating network structure for extended delivery of ophthalmic drugs

In the current work, hydrophilic silicone hydrogels were prepared for extended drug delivery applications. The preparation method was based on sequential interpenetrating network synthesis. A hydrophilic network was prepared by radical copolymerization of hydrophilic monomers 2‐hydroxyethyl methacrylate and poly(ethylene glycol) diacrylate. A hydrophobic silicone network was obtained by crosslinking polymerization of bifunctional methacrylated polydimethylsiloxanes macromonomer. The morphology of the silicone hydrogels was characterized by transmission electron microscopy. The result showed that the silicone hydrogels exhibited heterogeneous morphology. The properties of the silicone hydrogels such as equilibrium swelling ratio (ESR), mechanical property, oxygen permeability, contact angle, and protein repelling ability were investigated. Finally, the silicone hydrogels were loaded with timolol by pre‐soaking in drug solution to evaluate drug‐loading capacity and in vitro release behavior. The results showed that mechanical strength and oxygen permeability increased, and the ESR decreased with the increase of silicone component in the silicone hydrogels. The result of the contact angle measurement indicated that the silicone hydrogels possessed hydrophilic surfaces. The drug loading and in vitro releases were dependent on the composition of hydrophilic/hydrophobic phase of silicone hydrogels. Copyright © 2011 John Wiley & Sons, Ltd.     

Optically clear simulataneous interpenetrating polymer networks based on poly(ethylene glycol) diacrylate and epoxy. II. Kinetic study

Simultaneous interpenetrating polymer networks (SINs) based on diglycidyl ether of bis-phenol A (DGEBA) and poly(ethylene glycol) diacrylate (PEGDA) in weight ratios of 100/0, 50/50, and 0/100 were blended and cured simultaneously by using benzoyl peroxide (BPO) and m-xylenediamine (MXDA) as curing agents. A kinetic study during SIN formation was carried out at 45, 55, 63, and 70°C. Concentration changes for both the epoxide and C?C bond were monitored with FTIR. A rate expression for DGEBA cure kinetics was established with a model reaction of phenyl glycidyl ether (PGE) and benzylamine. Experimental results revealed that lower rate constants and higher activation energy for the SIN were found, compared with those for the constituent DGEBA and PEGDA network formation. A model of network interlock was proposed to account for this phenomenon. During simultaneous cure of DGEBA and PEGDA, the interlock (mutual entanglement) between DGEBA and PEGDA networks provided a sterically hindered environment, which subsequently increased the activation energy and reduced cure rates for both DGEBA and PEGDA. © 1993 John Wiley & Sons, Inc.     

Grafting of polymers with controlled molecular weight onto ultrafine silica surface

To graft polymers with controlled molecular weight and narrow molecular weight distribution, the grafting of polymers onto ultrafine silica surface by the termination of living polymer cation with amino groups introduced onto the surface was investigated. The introduction of amino or N-phenylamino groups onto the silica surface was achieved by the treatment of silica with γ-aminopropyltriethxysilane or N-phenyl-γ-aminopropyltrimethoxysilane. It was found that these amino groups on silica are readily reacted with living poly(isobutyl vinyl ether) (polyIBVE), which was generated with CF₃COOH/ZnCl₂ initiating system, and polyIBVE with controlled molecular weight and narrow molecular weight distribution is grafted onto the surface. By the termination of living poly(2-methyl-2-oxazoline), which was generated with methyl p-toluenesulfonate initiator, with amino groups on silica, polyMeOZO was also grafted onto the surface. The percentage of grafting of polymer onto the silica surface decreased with increasing molecular weight of the living polymer, because the steric hindrance of silica surface increases with increasing molecular weight of living polymer. Polymer-grafted silica gave a stable dispersion in a good solvent for grafted chains. © 1995 John Wiley & Sons, Inc.     

MMTCA recognition by molecular imprinting in interpenetrating polymer network hydrogels based on poly(acrylic acid) and poly(vinyl alcohol)

A novel IPN hydrogel designed to recognize MMTCA is prepared by applying the molecular-imprinting method. The IPN is characterized by FT-IR, DSC, and SEM. Langmuir analysis shows that an equal class of adsorption is formed in the hydrogel. The adsorption equilibrium constant and the maximum adsorption capacity are evaluated, and the effect of the pH on MMTCA adsorption is discussed. The selectivity of the imprinted polymer for MMTCA is studied in aqueous solutions of MMTCA/aspirin/riboflavin. The results suggest that the MMTCA-imprinted polymer shows superior selectivity for MMTCA as compared to riboflavin and aspirin. The reproducibility of the imprinted polymer to MMTCA is also studied.     

Interpenetrating polymer network hydrogels based on silicone and poly(2‐methacryloyloxyethyl phosphorylcholine)

In the present work, sequential interpenetrating polymer networks (IPNs) based on silicone and poly(2‐methacryloyloxyethyl phosphorylcholine) (PMPC) were developed with improved protein resistance. The structure and morphology of the IPNs were characterized by Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The results showed that the IPNs exhibited heterogeneous morphology. The bulk properties such as water content, ion permeability, and mechanical strength of the IPNs were determined by gravimetric method, ionoflux measurement technique, and tensile tester, respectively. The surface characteristics of the IPNs were investigated by X‐ray photoelectron spectroscopy (XPS) and contact angle measurements. XPS analysis suggested that PMPC was present on the surface as well as in the bulk material. The IPNs possessed more hydrophilic surface than pristine silicone revealed by contact angle measurements. Bovine serum albumin (BSA) was used as a model protein to evaluate protein resistance by a bicinchoninic acid assay method. The result revealed that the protein adsorption on the IPNs was significantly reduced compared to pristine silicone. These results suggest that the IPNs based on silicone and PMPC may be developed as novel ophthalmic biomaterials. Copyright © 2010 John Wiley & Sons, Ltd.     

Temperature-pH Sensitive IPN Hydrogels Composed of Silk Sericin and Poly （N-isopropylacrylamide）

In recent years IPN hydrogels have been attracted attentions as biomedical materials1-3. Among which poly(N-isopropylacrylamide) (PNIPAAm) was frequently used to impart temperature responsive function4, 5. Many of the second components were introduced for…