Synthesis of a novel antimicrobial-modified starch and its adsorption on cellulose fibers: part II––adsorption behaviors of cationic starch on cellulose fibers

The adsorption of guanidine polymer modified starches on cellulose fibers was investigated along with the systematic studies on various influencing factors including temperature, pH, ionic strength and charge density of the starches. The AFM results revealed the relationship between the adhesion force and adsorption capacity. The adsorption capacity is not necessarily proportional to the adhesion force. The conditions for achieving the maximum adsorption were: temperature, 40 °C; pH, 6; C_NaCl, 0 mM and charge density, 0.4 meq/g. The corresponding the normalized adhesion force is approximate 1 mN/m. In terms of the surface roughness determined by AFM, it has been proved that adsorbed starches of high charge density tend to form train structure, whereas those of low charge density tend to form tails and loops. Due the comb molecular structure, the adsorption capacity of the novel cationic starch reaches 124.3 mg/g, which is much greater than those reported previously.     

Holographic recording using visible-light sensitive polymers based on cationic polycondensation

Negative-working photopolymers based on a cationic polycondensation mechanism were developed. The photopolymers are highly sensitive to 488 nm argon ion laser light, because they use a chemically amplified reaction and are not sensitive to ambient oxygen. These photopolymers are composed of a poly(p-hydroxystyrene) matrix, a hexamethoxy methylmelamine crosslinker and a 2,4,6-tris(trichloromethyl)-1,3,5-triazine–coumarin dye combination as a photo-initiator. They exhibit 0.6 mJ/cm² (D^0.7_g) sensitivity to 488 nm light, as well as a high resolution of 0.5 μm. Due to their high sensitivity and high resolution, a relief-type hologram, larger than 50 × 50 cm, can be recorded in a short exposure time using them.     

5.3 Solvent cast cellulose diacetate film

A review of the historical development, manufacture, properties and applications of solvent-cast cellulose diacetate film.     

Adsorption of cationic surfactants and subsequent adsolubilization of organic compounds onto cellulose fibers

Cationic surfactants with different hydrophobic chain length were adsorbed onto cellulose fibers in an aqueous medium. The adsorption isotherms exhibited three characteristic regions which were interpreted in terms of the mode of aggregation of the surfactant molecules at the solid–liquid interface. The hydrophobic layers were used as a reservoir to trap various slightly water soluble organic molecules. A quantitative study of these phenomena suggested typical partition behavior of the organic solutes between the aqueous phase and the surfactant layer. The surfactant chain length (from C12 to C18) was shown to play an important role in terms of the capacity to retain the organic solute and the capacity increased with the number of carbon atoms.     

Reactions between cellulose diacetate and alkenylsuccinic anhydrides and characterization of the reaction products

Cellulose diacetate (CDA) with degree of substitution (DS) of 2.4 was dissolved in dimethylsulfoxide and reacted with octadecenyl succinic anhydrides (OSAs) using 1-methylimidazole as a promoter. FT-IR and ¹H-NMR analysis of the reaction products revealed that half-esterification occurred on residual hydroxyl groups of CDA by OSA, providing CDA/octadecenyl succinic acid (OSAcid) half esters at yields of more than 90%. The effects of reaction time and temperature on DS of CDA/OSAcid esters were studied in detail. The higher the reaction temperature, the higher the esterification rate to form CDA/OSAcid half esters. The maximum DS values were 0.41 and 0.33 for CDA/n-OSAcid and CDA/i-OSAcid esters, respectively. The original X-ray diffraction pattern of CDA changed with the introduction of OSAcid substituents into CDA, and CDA/OSAcid esters seemed to have thermoplasticity, depending on DS and the chemical structure of the OSAcids. A soil-embedding test of films of CDA and CDA/OSAcid esters indicated that the CDA/OSAcid esters that were prepared maintained the biodegradability of the original CDA.     

Poling and crosslinking processes in NLO polymers

A series of photocrosslinkable polymers bearing hyperpolarizable side chain chromophores was synthesized, poled and evaluated on the basis of the thermal stability of Second Harmonic Generation (SHG). Photoinitiation allowed for control of the onset of curing. Crosslinking was monitored by infrared spectroscopy and optimal conversion was achieved by applying a slow temperature ramp during exposure. The ultimate stability of the poled polymers was directly related to the number of crosslinking substituents that were attached to the chromophore pendant group. With two reactive groups per chromophore significant SHG was retained at temperatures above the initial polymer glass transition temperature. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2769–2775     

含1,8-二甲氧基-9,10-二氢蒽和巴比妥酸的发色团化合物的合成和NLO性质

在哌啶和醋酸催化下,1,8-二甲氧基-4,5-二甲酰基-9,10-二氢蒽和异佛尔酮巴比妥酸衍生物经Knoevenagel缩合合成了具有NLO性质的发色团化合物。在这些发色团中,环锁定的三烯和9,10-二氢蒽用作共轭桥,巴比妥酸和甲氧其分别作为吸电子和给电子基, 组成非共轭的两个D-π-A单位。溶剂变色法和紫外光谱研究证实它们比相应的参考物有较大的NLO活性并能保持与参考化合物相同的透光性。     

Synthesis and characterization of novel crosslinkable polymers with a nonlinear optical chromophore as a pendant group

New crosslinkable polymers with a nonlinear optical (NLO) active chromophore as a pendant group were synthesized by condensation chain polymerization via palladium‐catalyzed carbon–carbon coupling reactions. The polymerization yields were almost quantitative between the diiodobenzene (DIB) and diethyldipropargyl malonate (DEDPM) or 4‐(dimethylamino)‐4′‐(6‐dipropargylacetoxypropylsulfonyl)stilbene (DASS‐6) monomers. To improve the molecular weight and mechanical properties of the NLO active polymer, we carried out the copolymerization with DIB and DASS‐6 with various feed ratios of DEDPM. The resulting polymers were soluble in organic solvents and spun‐cast onto indium tin oxide‐coated glass substrates to make thin films. The molecular structures of the resulting polymers were characterized with various instrumental methods to confirm the carbon–carbon coupling reactions between the DIB and diacetylene monomers. The absorption of the ultraviolet–visible spectrum of the resulting polymers was drastically reduced after thermal curing at 160 °C because of the crosslinking of the reactive acetylene group in the polymer backbone. The electrooptic coefficient (r₃₃) measured at 1.3 μm ranged from 7 to 15 pm/V. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4025–4034, 2001     

Effect of sub-Tg relaxations on chromophore reorientation in corona-poled polymers

Activation volumes for chromophore reorientation were measured for a series of guest–host polymeric materials, indicating a significant coupling between chromophore motion and the glassy α and β relaxation dynamics of the polymer host. The specific systems studied were formed by individually dissolving N,N-dimethyl-p-nitroaniline (DpNA), 4-(dimethylamino)-4′-nitrotolane (DMANT), 4-(diethylamino)-4′-nitrotolane (DEANT), and 1-((4-(dimethylamino)phenyl)ethynyl)-4-((4-nitrophenyl)ethynyl)benzene (DMAPEANT) in poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate) (PEMA), and poly(isobutyl methacrylate) (PiBMA). In each of these systems, the isothermal, sub-T_g decay of the second-order optical susceptibility χ⁽²⁾ was monitored as a function of pressure using second harmonic generation. In each system, the observed decay of χ⁽²⁾ was represented by a stretched exponential equation from which the decay time τ₀ and decay distribution width β_KWW were determined. For each dopant molecule, the decrease in activation volume with the increasing size of the polymer host's alkyl side group and the pressure dependence of β_KWW were indicative of partial coupling between chromophore rotation and the glassy β relaxation dynamics of the polymer host. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1013–1024, 1998     

Microgels and ionic associations in solutions of cellulose diacetate

Solutions of cellulose diacetate (CDA) from two sources (cotton linters and wood pulp Floranier) were analysed in various solvents by size exclusion chromatography (SEC). Without special precautions, the SEC chromatograms presented three peaks — or prehumps — before the main polymer peak. The first prehump which could be eliminated by ultracentrifugation corresponded to microgels whose sugar composition was determined. These microgels were also investigated by electron microscopy, X-ray and electron diffraction analysis. They corresponded mainly to cellulose triacetate (CTA-II) in the case of CDA from cotton linters and a mixture of CTA-II and xylan diacetate (XDA) in the case of CDA from the wood pulp Floranier. The second and third prehumps could be attributed to ionic effects corresponding to the association of remaining sulfate groups on the CDA molecules with residual calcium. It was found that these ionic effects could be eliminated by the addition of LiBr or LiCl to the elution solvents. This led to chromatograms devoid of prehumps.Presented in part at the Cellulose '91 meeting in New Orleans.     

Synthesis and characterization of photorefractive polymers with triphenylamine unit and NLO chromophore unit on a side chain

Acrylate‐type copolymers (TPA‐DCV) consisting of triphenylamine (TPA) unit as a hole transport agent and dicyanovinyl aniline (DCV) as a second‐order nonlinear optical (NLO) chromophore on a side chain were synthesized. The polymers showed good solubility and sufficient morphological stability after film formation. The diffraction efficiency and gain coefficient increased as glass transition temperature decreased TPA‐DCV composite doped with fullerene (C₆₀) and dibutyl phthalate had a high photoconductivity of 5.1 × 10⁻¹² S/cm at the applied electric field of 50 V/µm. Diffraction efficiency and response rate were measured as functions of the parameters determining the photoconductivity (e.g. applied electric field, the density of the photocharges generated and writing beam intensity). The maximum diffraction efficiency and gain coefficient were 12.9% and 64 cm⁻¹, respectively, at an applied electric field of 80 V/µm. The maximum response time of 700 msec was obtained at the applied electric field of 80 V/µm. Photoconductivity, response rate and diffraction efficiency increased with the increase of the applied electric field. Field dependence of the response rate is attributed to the charge generation efficiency and/or the drift mobility. A similar power dependence of the photoconductivity and the response rate on the writing beam intensity was observed. The response rate and diffraction efficiency showed a good linear relationship with the logarithm of the photoconductivity. Copyright © 2000 John Wiley & Sons, Ltd.     

Epoxy-based azo polymers with high chromophore density: Synthesis,characterization and photoinduced birefringence

Three epoxy-based azo polymers(PEP-AZ-Cl,PEP-AZ-CN and PEP-AZ-NT) with high chromophore density were synthesized by using post-polymerization azo-coupling reactions between epoxy-based precursor polymer(PEP-AN) and diazonium salts of 4-chloroaniline,4-aminobenzonitrile and 4-nitroaniline,respectively.The structures and properties of the azo polymers were characterized by using ~1H-NMR,FT-IR,UV-Vis and thermal analyses.The photoinduced birefringence of the azo polymers was studied by irradiating spin-coated films of the polymers with laser beam at three different wavelengths(488,532,and 589 nm).The results indicate that the photoinduced birefringence of the azo polymers is related with the electron-withdrawing group on azo chromophores and the excitation wavelength.The excitation wavelength that can cause the efficient responses is determined by the absorption band positions of the azo chromophores,which are mainly affected by the electron-withdrawing group on the chromophores.Therefore,the azo polymers containing chromophores with different electron-withdrawing groups show different responsive behavior to the irradiation light at different wavelengths.When irradiated with 488 nm light,PEP-AZ-Cl shows the shortest time to reach the saturated birefringence but with the lowest saturation birefringence level compared with the other two azo polymers.When irradiated with 532 nm light,PEP-AZ-CN shows the shortest time to reach the saturated birefringence.When irradiated with 532 and 589 nm light,PEP-AZ-NT shows the highest saturation birefringence level.     

Design and synthesis of a thermally stable second‐order nonlinear optical chromophore and its poled polymers

A multiple charge‐transfer second‐order nonlinear optical (NLO) chromophore 2,3‐bis(4‐aminophenyl)‐5,6‐dicyanopyrazine (BAPDCP) was successfully designed and synthesized. It was characterized by ¹H NMR, mass spectrometry, Fourier transform infrared spectroscopy, and elemental analysis. The first hyperpolarizability β of BAPDCP was measured with the Hyper–Rayleigh scattering technique, which was 123.5 × 10^?30 esu. The donor‐embedded prepolyimide and prepolyurea were also synthesized by a polyaddition reaction. Thermogravimetric analysis and differential scanning calorimetry demonstrated that either the chromophore or the polymers have fine thermal stability. The thin films of prepolymers were prepared by coating on ITO glass substrate and poled by corona poling at elevating temperature. The second‐order NLO coefficients d₃₃ of the films were measured by in situ second‐harmonic generation measurements. The d₃₃ were deduced as 27.7 and 16.5 pm/V for polyurea and polyimide at 1064 nm fundamental wavelength, respectively. The onset depoling temperature of the polyimide and polyurea were both as high as 200 °C. To understand the temperature effect to the orientation thermal stability of polyimide, two films were treated at different final poling temperatures. The depoling experimental results showed that the orientation stability is higher, as raising the final treated temperature but the d₃₃ value are almost similar. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2846–2853, 2003     

A novel amphotropic polymer based on cellulose nanocrystals grafted with azo polymers

A novel amphotropic polymer which could exhibit liquid-crystalline behavior both in the solvent and in the heating process was synthesized through azo polymers grafting from cellulose nanocrystals (CNCs). The CNCs, prepared by acid hydrolysis of filter paper, were characterized by Atomic Force Microscopy (AFM). Poly{6-[4-(4-methoxyphenylazo)phenoxy] hexyl methacrylate}(PMMAZO), which was a liquid-crystalline polymers (LCP), was successfully to graft from CNC via Atom transfer radical polymerization (ATRP). The structure and thermal properties of the PMMAZO-grafted CNC were investigated using Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analyses (TGA). Its phase structures and transitions were studied by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The experimental results showed that the PMMAZO-grafted CNC exhibited both types of liquid crystal formation, thermotropic and lyotropic.     

Two-step preparation and thermal characterization of cationic 2-hydroxypropyltrimethylammonium chloride hemicellulose polymers from sugarcane bagasse

Cationic sugarcane bagasse hemicellulose derivatives with a relatively low degree of substitution (0.01-0.54) containing quaternary ammonium groups were prepared by etherification with 3-chloro-2-hydroxypropyltrimethylammonium chloride or preferably with 2,3-epoxypropyltrimethylammonium chloride using sodium hydroxide as a catalyst in aqueous solution. The extent of etherification was measured by yield percentage and degree of substitution (DS). The DS values of the products could be controlled by adjusting the molar ratio of etherifying agent to anhydroxylose units in hemicelluloses and the molar ratio of sodium hydroxide to etherifying reagent. In comparison, the etherified hemicellulose preparations were characterized by both degradative methods such as thermal analysis, and non-degradative techniques such as gel permeation chromatography (GPC), Fourier transform infrared (FT-IR), and ¹³C nuclear magnetic resonance (NMR) spectroscopy. It was found that a significant degradation of the hemicellulose polymers occurred during etherification under the alkaline conditions used. The thermal stability of the etherified hemicelluloses was lower than that of the unmodified hemicellulose polymers.     

Second harmonic generation in polymers containing a new azo chromophore based on phenylnitrobenzoxazole

The synthesis of the new chromophores 2‐{4‐[4‐(N,N‐dihydroxyethylamino)‐phenylazo]‐phenyl}‐6‐nitrobenzoxazole ( 1 ) and 4‐[4‐(N,N‐dihydroxyethylamino)phenylazo]‐benzoic acid ( 2 ) is described. Three homopolymers obtained by the polycondensation of 1 with propyloxy‐terephthalic acid and 1 and 2 with 2,4‐tolylenediisocianate as well as two copolymers obtained by polycondensation of appropriate mixtures of chromophores 1 and 2 with 2,4‐tolylene‐diisocianate were prepared and characterized. All as‐prepared polymers but one (homopolyurethane of 1 ) were amorphous and exhibited good optical clarity, good thermal stability above the glass transition, and solubility in organic solvents. The second‐order nonlinear optical behavior of the amorphous polymers was investigated on spin‐coated corona‐poled films through second harmonic generation (SHG) experiments at 1064 nm. At this wavelength, resonance‐enhanced values of the SHG coefficient d₃₃ were found in the range between 6 and 34 pm/V where higher values were observed for polymers with a higher molar content of 1 . © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1468–1475, 2002     

Bottlebrush‐shaped copolymers with cellulose diacetate backbone by a combination of ring opening polymerization and ATRP

Graft copolymers with cellulose diacetate (CDA) backbone and both the poly(ε‐caprolactone) and polystyrene, or poly(butyl acrylate) or PMMA grafts were prepared by two‐step process. First, ε‐caprolactone (CL) was polymerized by ring‐opening polymerization (ROP) initiated with CDA, partly funcionalized with 2‐bromo‐isobutyryl groups (degree of functionalization was 0.5). The p(CDA‐g‐CL) copolymers were used in the second step as polyfunctional macroinitiators of ATRP of the vinyl monomer, giving densely grafted copolymers with polyester and PSt, or PBuA, or PMMA grafts. The prepared copolymers were characterized by SEC, some of them also by FTIR spectroscopy and atomic force microscopy (AFM). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 564–573, 2008     

Effect of microcrystalline and nanocrystals cellulose fillers in materials based on PLA matrix

The aim of this work was to compare the effects of microcrystalline cellulose (MCC) and cellulose nanocrystals (CNC) addition on the properties of PLA matrix. The CNC were obtained by acid hydrolysis of the MCC. Both MCC and CNC were separately incorporated in PLA at ratios of 3, 5 and 7 wt%. In some compositions, organophilic silica (R972) was added to improve the cellulose-matrix compatibility. The properties of the materials were evaluated by FTIR, XRD, NMR and mechanical tests. Functional groups and crystalline structure of MCC and CNC were determined by FTIR and XRD, respectively. NMR T₁H values showed that films containing CNC presented better interfacial interaction than those containing MCC, and indicated that R972 acts as compatibilizer. MCC and CNC acted as nucleating agents for PLA crystallization and there was an improvement in the mechanical performance of materials with the addition of CNC.