醋酸羟丙基甲基纤维素琥珀酸酯的合成

以羟丙基甲基纤维素(HPMC)为原料,琥珀酸酐、乙酸酐为酯化剂,在醋酸中进行酯化反应制备了醋酸羟丙基甲基纤维素琥珀酸酯(HPMCAS)。通过改变影响基团质量分数的各种因素条件,得到了不同取代度的产物。采用滴定法测定了琥珀酰基、乙酰基的质量分数,并对产品结构进行表征和性能测试。结果表明,该反应体系在105℃反应6.5 h,反应后选用去离子水为沉淀剂,机械搅拌(750 r/min)使产物沉析,可得到琥珀酰基和乙酰基质量分数分别为13%和8%左右的产品。获得的产品HPMCAS多分散系数为1.06,相对分子质量(简称分子量,下同)分布较窄,在丙酮、甲醇等溶剂中表现出良好的溶解性能,并在200℃前对热稳定。     

Preparation and characterization of composite gels and films containing gelatin and hydroxypropyl methylcellulose phthalate

Composite gels and films were prepared by the blending of hydrated gelatin as a base material and hydroxypropyl methylcellulose phthalate (HPMCP) at various mass ratios. A composite technology was applied to obtain improved mechanical, physicochemical, and antimicrobial properties of the gelatin used as a base material. We investigated the effects of different experimental conditions on the rheological and mechanical properties and antimicrobial activities of the composite gels, films, and solutions. The rheological values (storage modulus, loss modulus, and complex viscosity) of the composite solutions and gels increased with added HPMCP. Aerobic microorganisms, yeasts, and molds were not detected throughout the testing period in the gelatin–HPMCP composite solution. In contrast, many microorganisms were detected in the gelatin‐only samples beginning with day 3 of storage. The composite films exhibited relatively good mechanical and physical properties compared with the gelatin‐only film. The composite film containing HPMCP at a mass ratio greater than 1:4 did not dissolve in gastric juice (pH 1.2) for at least 2 h, but all other samples, including the gelatin‐only film dissolved in enteric juice (pH 6.8). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39597.     

Synthesis of chitosan beads as boron sorbents

Parameters, such as pH, temperature, initial boron concentration, adsorbent dosage, and ionic strength, affecting boron adsorption onto chitosan beads were examined in this study. The following values were obtained as the optimum conditions in our studied ranges: pH 8.0, temperature = 308 K, amount of chitosan beads = 0.15 g, initial boron concentration = 4 mg L⁻¹, and ionic strength = 0.1 M NaCl]. The adsorption kinetics were also examined in terms of three kinetic models: the pseudo‐first‐order, pseudo‐second‐order, and intraparticle diffusion models. The pseudo‐second‐order kinetic model showed very good agreement with the experimental data. Intraparticle plots seemed to have two steps and indicated multilinearity. Equilibrium data were evaluated with nonlinear and linear forms of the Langmuir and Freundlich equations. The experimental data conformed to the Freundlich equation on the basis of the formation of multilayer adsorption. To characterize the synthesized chitosan beads, we used Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) analyses. As shown by FTIR analysis, the boron species may have interacted with the NH₂ groups on chitosan. Microparticles of about 5 μm appeared in the SEM micrographs of the chitosan beads. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

新型硫氮杂冠醚化合物的合成与表征

经取代、氯乙酰化、成环3步反应合成两种新的硫氮杂冠醚化合物,产率>90%。该合成方法具有反应条件温和,容易提纯等优点。化合物结构经IR、NMR、MS以及元素分析确定。     

Synthesis and swelling characteristics of responsive carboxybetaine gel

A polyimminium gel, Dimedone‐[N, N′ melaminium] butyrocarboxylate copolymer, comprising of zwitterionic carboxybetaine repeat units was synthesized via a catalyst free facile polycondensation approach. The polymer was studied for its photoluminescence, thermal, and swelling behavior. Swelling behavior was investigated in different solvent mixtures as well as in pure solvents. The extent of swelling was dictated by solvent composition, such as dielectric constant, pH, ionic strength, and other variables for instance, temperature and crosslinking density. Gel was soluble in alkali and could be regenerated on treatment with an acid. This pH responsive behavior could find various industrial applications, especially in wastewater treatment. A preliminary study on sorption of dyes was also carried out. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

流通色谱介质的研制和性能研究

应用固液联合致孔模式和自由基悬浮聚合技术,研制成功了双孔球形流通色谱介质。对该介质的结构、吸附性能和色谱行为进行研究并与小孔球形介质作比较。双孔流通色谱介质和小孔介质的静态吸附容量相近,分别为55.6和63.8mg/g。在12cm/min流速下双孔球形流通色谱柱介质和小孔球形柱介质对BSA的动态吸附容量分别为40和24mg/mL。随着流速的增加,小孔介质动态吸附容量显著下降,而双孔球形流通色谱介质的动态吸附容量的变化很小,证明其在高速色谱分离中的优势。     

Mechanical and swelling properties of polyacrylamide gel spheres

Spheres of crosslinked acrylamide-methylene bisacrylamide copolymer were produced by suspension polymerization. By introducing a vibrating stream of aqueous solution into an organic matrix, particle sizes of 0.33 ± 0.06 to 0.99 ± 0.41 mm in diameter resulted. The swelling of gel spheres in water was compared to that of larger ‘bulk’ gels, and a significant amount of hydrolysis occurred in the spheres due to the presence of tetramethylethylenediamine (TEMED), used as an initiator. The dependence of the elastic modulus of the gel spheres upon the crosslinker concentration was non-linear, even in the regime where linearity is observed for bulk gels; this appears to be due to the varying amounts of TEMED that diffuses in the spheres and is known to affect the modulus of bulk gels.     

Study on phenolic resin beads: Effect of reaction parameters on the properties of polymeric beads

Well‐sized spherical beads of phenolic resin (0.3–1.2 mm) with an extremely high compressive strength (>8 kg/1.0 mm bead) and hardness (>98%) were synthesized via suspension polymerization of phenol and formaldehyde. Barium hydroxide was used as a catalyst (1.68–10.13 wt %) to get larger size of resin beads. Poly(vinyl alcohol) (5.0–12.5 wt %) and hexamethylene tetramine were used as stabilizing agent and crosslinking agent, respectively. Comprehensive studies elucidated a specific relation between the reaction parameters and properties of the resin beads. Yield was found proportional to catalyst concentration and inversely proportional to stabilizing agent concentration. Particle size distribution curves got contracted and shifted toward a lower size range with higher concentration of catalyst and stabilizing agent. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

In situ gel forming systems of poloxamer 407 and hydroxypropyl cellulose or hydroxypropyl methyl cellulose mixtures for controlled delivery of vancomycin

Poloxamers are a family of triblock copolymers consisting of two hydrophilic blocks of polyoxyethylene separated by a hydrophobic block of polyoxypropylene, which form micelles at low concentrations and form clear thermally reversible gels at high concentrations. The objective of this study was to develop an in situ gel forming drug delivery system for vancomycin using the minimum possible ratio of poloxamer 407 (P407). Decreasing the concentration of poloxamer could reduce the risk of hypertriglyceridemia induction. Different additives were added to the poloxamer formulations. It was observed that among different additives, hydroxypropyl methyl cellulose (HPMC) and hydroxypropyl cellulose (HPC) can decrease poloxamer concentration required to form in situ gelation from 18 to 10%. The dynamic viscoelastic properties of the samples were determined. Both the storage modulus and the loss modulus of the samples increased abruptly as the temperature passed a certain point. The gelling temperature was in the order of P407 : HPC (10 : 10 w/w) < P407 : HPMC (10 : 10 w/w) < P407 : HPMC (15 : 5 w/w) < P407 : HPC (15 : 5 w/w). Drug release rate could be controlled by changing the type and ratio of additives as well as the amount of drug loaded. It can be concluded that combining P407 and cellulose derivatives could be a promising strategy for preparation of thermally reversible in situ gel forming delivery systems with low poloxamer concentration. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and characterization of poly(methyl methacrylate) beads

The phase behavior of Poly(ethylene terephthalate)/Poly(ethylene‐2,6‐naphthalate)/Poly(ethylene terephthalate‐co‐ethylene‐2,6‐naphthalate) (PET/PEN/P(ET‐co‐EN)) ternary blends in molten state was evaluated from differential scanning calorimetry (DSC) and NMR results as well as optical microscopic observations. Copolymer of ethylene terephthalate and ethylene‐2,6‐naphthalate was prepared by a condensation polymerization, which was a random copolymer with an intrinsic viscosity (IV) of 0.3 dL/g. The phase diagram of the ternary blends revealed that the miscibility of ternary blends in molten state was dependent on the fraction of P(ET‐co‐EN) in the blends and holding time of the blends at high temperatures above 280°C. With increase in the holding time, the fraction of copolymer in the blends necessary to induce the immiscible to miscible transition decreased. For the blends with longer holding time at 280°C, the phase diagram in molten state was irreversible against the temperature, although a reversibility was found for the blends with short holding time of 1 min at 280°C. The irreversibility of phase behavior was not explained simply by the increase of copolymer content produced during heat treatment. Complex irreversible physical and chemical interactions between components and change of phase structure of the blend in the molten state might influence on the irreversibility. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Molecular and mechanical properties of hydroxypropyl methylcellulose solutions during the sol:gel transition

This paper outlines the latest findings in our work to understand the fundamental interactions within hydrated hydroxypropyl methylcellulose (HPMC) at elevated temperature. ATR-FTIR spectroscopy was used to relate molecular interactions to the rheological changes in aqueous HPMC solutions during the sol:gel transition. Sol:gel transition temperatures determined using ATR-FTIR spectroscopy, oscillatory rheology and turbidimetry were in agreement to within experimental error. ATR-FTIR spectroscopy provided direct evidence of increased hydrophobic interactions within the gel network through a shift to lower wavenumber of ν_as(CH) vibrations observed during the gelation process. In addition, the FTIR spectra provide evidence that the structure of the polymer network is different in the thermo-formed gel, to that which exists in viscous solution. Both the rheological and ATR-FTIR data confirmed the supposition that thermal gelation is a two stage process. The first stage has been attributed to the disruption of native cellulosic bundles and this is supported by the changes in both the storage modulus and intensity of the ν(CO) band at low temperatures. The second stage corresponded to phase separation and gelation resulting from increased hydrophobic interactions between polymer chains at elevated temperatures.     

Synthesis and characterization of polyelectrolyte hydrogels with controlled swelling behaviour

Copolymerization of sulfopropyl methacrylate potassium salt (K‐SPMA) and 2‐acrylamido‐2‐methyl propane sulfonic acid (AMPS) has been studied in the range 10–90% K‐SPMA in the feedstock. The reactivity ratios have been determined for K‐SPMA/AMPS copolymers. The copolymer compositions, utilized for determining the reactivity ratio, have been determined from nitrogen content. Crosslinked poly(AMPS) and K‐SPMA/AMPS copolymers were prepared in water in the presence of potassium persulfate as initiator and N,N‐methylene bisacrylamide (MBA) as tetrafunctional crosslinker. Irradiation of K‐SPMA and AMPS with an electron‐beam was carried out at 50 wt% aqueous solution with low pH and irradiation dose 40–120 kGy. The swelling behaviour of highly crosslinked K‐SPMA/AMPS copolymer polyelectrolyte gels in aqueous medium was studied in the presence of different types of salts. The crosslink density, the average molecular weight between the crosslinks and the dissociation constant (pK_a) of the crosslinked polymer were determined from stress–strain measurements. © 2001 Society of Chemical Industry     

Synthesis and characterization of silver nanoparticle incorporated gelatin‐hydroxypropyl methacrylate hydrogels for wound dressing applications

A replaceable wound cover which absorbs moisture and resist infection can be used to prevent development of chronic wounds. A major criterion for a replaceable wound dressing is nonadherence to cells to prevent pain upon removal. A major limitation of water absorbing hydrogels used in wound dressing applications is their poor mechanical strength. In this study, gelatin methacrylate (GelMA) was synthesized by reacting Type A porcine skin gelatin with methacrylic anhydride at 50 °C. Resultant GelMA monomer containing polyethylene glycol (PEG) protected silver nanoparticles were subsequently copolymerized with 2‐hydroxypropyl methacrylate (HPMA) at room temperature by redox mechanism. This resulted in a hydrogel copolymer with optimum mechanical stability and moisture retention while inhibiting microbial contamination and FT‐IR spectroscopy was used to confirm copolymer formation. Antimicrobial properties of the hydrogel using agar diffusion showed zone of inhibition against Staphylococcus aureus. Surface morphology was observed using scanning electron microscopy (SEM) and elemental analysis was carried out using energy‐dispersive spectroscopy (EDS). Micro‐computed tomography (micro‐CT) analysis of the hydrogel showed enhancement in the pore size from around 32 µ to 48–64 µ after incorporation of silver nanoparticles. Degradation of the hydrogel was observed after 48 h when stored in PBS containing collagenase enzyme. In vitro cell culture experiments established absence of cytotoxicity in the hydrogel and nonadherence character to dermal fibroblasts. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44529.     

Pd(II) ion adsorption onto emulsion gel beads in a fixed bed

We developed previously an emulsion gel adsorbent for improved metal adsorption. This study focuses on a continuous adsorption–desorption process of metal ions from a solution onto emulsion gel beads using the fixed-bed method. The monodisperse millimeter-sized emulsion gel beads, a polymeric hydrogel containing randomly distributed oil microdroplets of di-n-hexylsulfide as an extractant, were prepared using an automatic production method combining sedimentation polymerization and two-fluid atomization. The isotherms and the kinetics for Pd(II) adsorption were investigated. A continuous adsorption–desorption process was successfully demonstrated, and the breakthrough curve was successfully predicted by a mathematical analysis.     

Syntheses of hydroxypropyl methylcellulose phthalate hydrogels in Na2CO3 aqueous solutions with electron‐beam irradiation

Novel cellulose ether hydrogels were prepared by the radiation‐induced crosslinking of hydroxypropyl methylcellulose phthalate (HPMCP) in a solution of Na₂CO₃. The effects of several factors, such as the HPMCP concentration, Na₂CO₃ concentration, absorbed dose, and dose rate, on the crosslinking of HPMCP were investigated in detail. An increase in the HPMCP concentration resulted in an increasing content of the gel fraction, and this meant that the crosslinking probability increased as well. Na₂CO₃ was essential for dissolving HPMCP in water, and a 4–5% Na₂CO₃ aqueous solution was optimal for the crosslinking of HPMCP. The dose rate also affected the radiation crosslinking of HPMCP; hydrogels with higher gel fractions and transparency could be formed at lower dose rates. The ratio of degradation to crosslinking of the gel was calculated according to the Charlesby–Rosiak equation, and it showed good agreement with the experimental results. Some important properties, such as the swelling kinetics, ion and ionic strength dependence, and pH dependence, of the HPMCP hydrogels were also investigated. The HPMCP hydrogels possessed excellent swelling rates and swelling ratios in some solvents, such as water and methanol, with a high hydrogen‐bonding parameter. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2123–2130, 2003     

聚4-乙烯基吡啶的合成与表征

以过氧化二苯甲酰(BPO)为引发剂,用悬浮聚合的方法制备了较高相对分子质量的聚4 乙烯基吡啶(P4VP)。通过对聚合产物相对分子质量测试结果的分析,研究了单体与水的体积比、引发剂用量、分散剂用量、反应时间、反应温度、搅拌速度等因素对4 VP聚合反应的影响。结果表明,聚合时间为1h、聚合温度为60℃、引发剂的质量分数(占单体量)为0.8%左右、分散剂的质量分数(占单体量)为0.6%、搅拌速度为300r/min时,P4VP的重均分子量就能达到6×105～9×105。另外,采用紫外吸收光谱(UV)、红外吸收光谱(IR)、核磁共振氢谱(1H NMR)、核磁共振碳谱(13C NMR)、热重 差热分析(TG DTA)等测试手段研究了P4VP的结构和性能。     

Hydrogel‐MWCNT nanocomposites: Synthesis,characterization, and heating with radiofrequency fields

Hydrogel nanocomposites are attractive biomaterials for numerous applications including tissue engineering, drug delivery, cancer treatment, sensors, and actuators. Here we present a nanocomposite of multiwalled carbon nanotubes (MWCNT) and temperature responsive N‐isopropylacrylamide hydrogels. The lower critical solution temperature (LCST) of the nanocomposites was tailored for physiological applications by the addition of varying amounts of acrylamide (AAm). The addition of nanotubes contributed to interesting properties, including tailorability of temperature responsive swelling and mechanical strength of the resultant nanocomposites. The mechanical properties of the nanocomposites were studied over a range of temperatures (25–55°C) to characterize the effect of nanotube addition. A radiofrequency (RF) field of 13.56 MHz was applied to the nanocomposite discs, and the resultant heating was characterized using infrared thermography. This is the first report on the use of RF to remotely heat MWCNT‐hydrogel nanocomposites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Acetylation of poly(2-hydroxyethyl acrylate) gel beads obtained from sedimentation polymerization

Sedimentation polymerization of an aqueous 2-hydroxyethyl acrylate solution with some crosslinkers was carried out using a simple sedimentation polymerization apparatus to give millimeter-size and very narrow size distributed poly(2-hydroxyethyl acrylate) (PHEA) gel beads. Also, heterogeneous acetylation of the resulting PHEA gel beads with acylating agents such as acetic anhydride, a mixture of acetic anhydride and pyridine, and chloroacetic anhydride was performed under various conditions. The selective esterification of PHEA gel beads proceeded smoothly in toluene from surface to give a novel core-shell type gel consisting of an unreacted core and acetylated shell, and finally afforded almost quantitatively acetylated PHEA gel. The unreacted core became small while maintaining a spherical shape during reaction. The reaction resembled to that of the corresponding cylindrical PHEA gel, and was strongly affected by the network structure of the obtained PHEA gel beads and the reactivity of acylating agents.     

Synthesis and characterization of hydroxypropyl terminated polydimethylsiloxane‐polyurethane copolymers

Polyurethane (PU) block copolymers were synthesized using prepared hydroxypropyl terminated polydimethylsiloxane (HTPDMS MW 990) and polyether diols (N‐210) as soft segment with 4,4′‐diphenylmethane diisocyanate (MDI) and 1,4‐butanediol. This low molecular weight polydimethylsiloxanes (PDMS) containing hydroxypropyl end‐groups displayed better compatibility with PU than common PDMS. In this article, we illustrate its synthesis routes and confirmed the proposed molecular structures using NMR and infrared radiation (IR). We varied the contents of HTPDMS and N‐210 in soft segments (HTPDMS—N‐210: 0 : 100, 20 : 80, 40 : 60, 60 : 40, 80 : 20, and 100 : 0) to synthesize a series of PDMS‐PU copolymer. IR spectroscopy showed the assignment characteristic groups of each peak in copolymers and confirmed that the desired HTPDMS‐PU copolymers have been prepared. The different thermal, dynamic mechanical and surface properties of the copolymers were compared by thermogravimetry, DMA, contact angle and solvent resistance. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013