Synthesis,characterization, and enzymatic degradation of starch-grafted poly(methyl methacrylate) copolymer films

Graft copolymerization of methyl methacrylate (MMA) onto the corn starch (CS) backbone was carried out in an aqueous medium using ceric ammonium nitrate as an initiator under nitrogen atmosphere. The weight ratio of CS/MMA varied with their composition, as 7/3, 6/4, 5/5, 4/6, and 3/7 were used in this study of the graft efficiency and graft percentage (GP); thus, five different GP CS-g-PMMA copolymers were obtained. The molecular weight of CS-g-PMMA copolymers were measured by using gel permeation chromatography. The structure of CS and CS-g-PMMA copolymer were confirmed by infrared spectra. CS and CS-g-PMMA copolymers were characterized by thermal gravimetric analysis, differential scanning calorimetry, and scanning electron microscopy (SEM). Horowitz-Metzger and Broido methods were applied to investigate the thermal decomposition kinetics of CS-g-PMMA copolymers. The effect of GP on the activation energy of decomposition, crystallization behavior, and morphology was investigated. In addition, the biodegradability of CS-g-PMMA films were also studied by α-amylase treatment with different times. The weight loss of CS-g-PMMA films after α-amylase treatment were calculated. Finally, the morphology of CS-g-PMMA films before and after α-amylase treatment were observed by SEM photograph. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

聚苯乙烯- 甲基丙烯酸甲酯接枝共聚物的合成

通过氯甲基化反应在线型聚苯乙烯（ＰＳ）的苯环上定量地引入氯甲基（—ＣＨ２Ｃｌ）,合成了氯甲基化聚苯乙烯大分子引发剂ＰＳ—ＣＨ２Ｃｌ,在氯化亚铜／α,α′－联二吡啶配合物（ＣｕＣｌ／ｂｐｙ）催化下,以ＰＳ—ＣＨ２Ｃｌ引发甲基丙烯酸甲酯（ＭＭＡ）聚合,合成了聚苯乙烯－甲基丙烯酸甲酯接枝共聚物。用红外光谱和核磁共振氢谱证实了接枝共聚物的结构,测定了接枝共聚物中ＰＭＭＡ支链数目、接枝共聚物的支链长度、接枝率及接枝效率。结果表明,用这种方法制备的接枝共聚物相对分子质量分布较窄,接枝率可控,接枝效率高达９２％～９８％。     

Blended graft copolymer of carboxymethyl cellulose and poly(vinyl alcohol) with banana fiber

Conducting hydrogel copolymer was prepared by graft copolymerization of carboxymethyl cellulose (CMC) and boric acid onto poly(vinyl alcohol) (PVA). The dielectric properties of CMC‐g‐PVA/prehydrolyzed banana blend have been investigated as a function of frequency, with special reference to pure prehydrolyzed banana. Also, the static bending for the blend was determined and no abrupt failure was observed. The dielectric properties measured were dielectric constant (ε′), dissipation factor (tan δ), and loss factor (ε″). At high frequencies, a transition in the relaxation behavior was observed, whereby the dielectric constant, loss tangent, and loss factor decreased with frequency. Experimental ε′ values of the blend are greater than those of prehydrolyzed banana. The dielectric behavior depends greatly on the nature of the present group, the crystallinity of the system, and the degree of hydrogen bonding between the different chains. The variation of the dielectric properties was correlated with blend morphology and also to the possibility for interfacial polarization that arises because of the differences in conductivities of the two phases. It was found from the infrared spectra that the incorporation of CMC‐g‐PVA copolymer decreases the crystallinity of the blend and also decreases the degree of hydrogen bonding, which results in a high dielectric constant. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1842–1848, 2006     

Synthesis and characterization of an amphiphilic graft copolymer with a poly(acrylic acid) backbone and n-octylphenyl polyoxyethylene side chains

A novel, well-defined, amphiphilic graft copolymer was synthesized by the free-radical copolymerization of acrylic acid and an amphiphilic macromonomer, n-octylphenyl polyoxyethylene acrylate. This acrylic copolymer was characterized by IR and ¹H-NMR. The number-average molecular weight was determined by gel permeation chromatography to be 4.37 × 10⁴ (weight-average molecular weight/number-average molecular weight = 1.23). The graft copolymer exhibited good solubility in water and high surface activity at much lower concentrations. The molecules of the AA–C₈PhEO₁₀Ac copolymer formed polymolecular micelles at 3.0 × 10⁻⁴ g/mL. The aggregation of the copolymer was examined in aqueous solution by measurement of the fluorescence of 2-p- toluidinylnaphthalene 6-sulfonate as a fluorescent probe. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of amphiphilic hydroxypropylcellulose‐graft‐poly(ε‐caprolactone)

An amphiphilic graft copolymer, hydroxypropylcellulose‐graft‐poly(ε‐caprolactone) (HPC‐g‐PCL), was synthesized by bulk polymerization without a catalyst and characterized with one‐dimensional and two‐dimensional NMR spectroscopy. Molar substitution of ε‐caprolactone on HPC (MS_CL) was estimated by both gravimetry and ¹H‐NMR, and the gravimetric method was considered suitable for MS_CL determination. Heterogeneity in the HPC‐g‐PCL film was suggested by a microscopic study, and the existence of PCL‐rich crystalline regions was confirmed by the results of X‐ray diffraction and differential scanning calorimetry (DSC). The double endotherm observed in the DSC scans of HPC‐g‐PCL was associated with the different molecular weight fractions in the copolymer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 718–727, 2003     

Preparation of cellulose acetate butyrate and poly(ethylene glycol) copolymer to blend with poly(3‐hydroxybutyrate)

A two‐step procedure was used to synthesize the cellulose acetate butyrate and poly(ethylene glycol) graft copolymer (CAB‐g‐PEG). By choosing the appropriate composition, the crosslinked graft copolymer or not could be obtained. Then, the CAB‐g‐PEG copolymer was blended with poly(3‐hydroxybutyrate) (PHB), to further improve the mechanical properties of PHB. The results indicated that PHB and CAB‐g‐PEG that were not crosslinked were miscible over the entire composition range. As the CAB‐g‐PEG copolymer increased in the PHB/CAB‐g‐PEG blends, the melting temperature of the blends decreased, the crystallization of PHB became more difficult, and the crystallinity of the blend and PHB phase all decreased. The tensile properties and impact strength of the PHB/CAB‐g‐PEG blends were superior to the PHB/CAB blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1471–1478, 2006     

Synthesis and characterization of brush copolymers based on methoxy poly(ethylene glycol) and poly(ε‐caprolactone)

Brush copolymers composed of methoxy poly(ethylene glycol) (MPEG) and poly(ε‐caprolactone) (PCL) have been synthesized by the ring‐opening polymerization of ε‐caprolactone initiated by hydroxyl function of thermally esterified MPEG‐citrate in presence of stannous octoate. Citric acid (CA) acts as spacer between brush‐like MPEG and the long chain of PCL. Existence of hydrophobic domains as cores of the micelles were characterized by ¹H NMR spectroscopy and further confirmed with fluorescence technique using pyrene as a probe. Critical micelle concentration (CMC) of the synthesized copolymer decreased from 0.019 to 0.0031 mg/mL on increasing the fraction of PCL. Along with the physicochemical study, the brush copolymers were explored for the preparation of nanoparticles by nanoprecipitation technique. The morphology and geometry of micelles were investigated by using DLS, AFM, and TEM. Hydrodyanamic dimensions of micelles were around 118 and 178 nm with the core size of 8–10 nm, which further aggregated to form secondary micelle of 60–90 nm. Such assembled polymeric micelles with its flexible dendritic MPEG corona could hold a promise for the immobilization (encapsulation) of hydrophobic drugs and subsequently promote sustained release so that it can be a good vehicle for anti‐cancer drug deliverance. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Compatibilization of the poly(lactic acid)/poly(propylene carbonate) blends through in situ formation of poly(lactic acid)‐b‐poly(propylene carbonate) copolymer

The in situ formation of poly(lactic acid)‐b‐poly(propylene carbonate) (PLA‐b‐PPC) block copolymers were carried out by the reaction between PLA and PPC in the presence of tetrabutyl titanate via transesterification. Molecular weight measurements and ¹³C nuclear magnetic resonance spectroscopy revealed that PLA‐b‐PPC block copolymers with higher molecular weight were obtained by controlling the reactivity point ratio between PLA chains and PPC chains in PLA/PPC reaction system. The sample with a composition of PLA:PPC = 40:60 (wt %) and a catalyst amount of 0.5 wt % had a more proportionable reactivity point ratio between PLA chains and PPC chains compared with other samples, resulting in a most conspicuous transesterification and inconspicuous chain scission reaction. Therefore, its high molecular weight fraction (M_w > 40.0 × 10⁴) increased 80%. The formation of macromolecular PLA‐b‐PPC copolymer could strengthen the entanglement between PLA and PPC molecular chains, which resulted in an increased viscosity of blends at low shear rate. In addition, the elongation at break of sample with a composition of PLA:PPC = 40:60 (wt %) and a catalyst amount of 0.5 wt % was nearly as twice as which without catalyst because of the improving miscibility of PLA domains and PPC matrix by the compatibilization of PLA‐b‐PPC copolymer. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46009.     

Synthesis and application of a new vinyl copolymer superplasticizer

A new vinyl graft copolymer superplasticizer was synthesized by copolymerization of polyethylene glycol acrylate (PEGAA), polyethylene glycol biester of maleic acid and citric acid (PEGMC), acrylic acid (AA), sodium allylsulphonate (SAS), and methyl acrylate (MA). The effects of the vinyl monomers' molar ratio, initiator, reaction temperature, and reaction time on its application properties were investigated. The results show that the new vinyl graft copolymer superplasticizer has excellent application properties when the molar ratio of PEGAA, PEGMC, AA, SAS, and MA is 0.5 : 0.10 : 0.20 : 0.05 : 0.03 and the initiator ammonium persulfate [(NH₄)₂S₂O₈, APS] is 0.8 wt % at 80°C for 3 h. The vinyl monomers' conversion is 98.7%. The applied results show that the water‐reducing ratio and retardation solidification time of the superplasticizer reach 33.5% and 4 h, respectively. The applied concrete has excellent mechanical properties. Its molecular structure was characterized by nuclear magnetic resonance, Fourier transform infrared spectra, and gel permeation chromatography. It is characteristic of the new vinyl graft copolymer superplasticizer that citric acid (CA) and MA are introduced into the copolymer molecules. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

聚(丙烯酸-丙烯酰胺)接枝辛基酚聚氧乙烯醚丙烯酸酯两亲性共聚物的合成及表征

以辛基酚聚氧乙烯醚丙烯酸酯(C8PhEO10Ac)为大分子单体,丙烯酸(AA)、丙烯酰胺(AM)为共聚单体,采用大分子单体接枝共聚法,制备了一种两亲性接枝共聚物(AA-AM-g-C8PhEO10Ac),用静态光散射(SLS)与GPC联用技术测得接枝共聚物的分子量为9.51×105,用FTIR、1H NMR和TG/DTA等手段对共聚物的结构及性能进行了表征。采用透射电子显微镜(TEM)对聚合物在水溶液中的自组装行为进行了初步研究。结果表明,AA-AM-g-C8PhEO10Ac在水溶液中自组装,形成球型胶束,随着浓度增大,趋向于形成更大的自组装体。     

以羟乙基纤维素为骨架的环境敏感共聚物的合成及性能研究

通过铈离子在酸性条件下氧化还原引发,成功得到了以羟乙基纤维素(HEC)为主链,以聚甲基丙烯酸N,N-二甲氨基乙酯(PDMAEMA)为支链的接枝共聚物,利用红外、核磁对产物进行了结构表征;探讨了接枝聚合的反应机理;利用旋转流变仪对该共聚物的水溶液做了粘温曲线测试,对它的最低临界转变温度(LCST)进行了观察;通过透射电镜照片初步研究了接枝产物在不同pH值和不同外加盐浓度下的自组装行为。     

Mechanical properties of poly(vinyl chloride) blends and corresponding graft copolymers

The mechanical properties of the poly (vinyl chloride) (PVC) and poly (glycidyl methacrylate) [poly (GMA)] blend system and the PVC and poly (hydroxyethyl methacrylate) [poly (HEMA)] blend system and their crosslinked films were investigated. At the same time, the mechanical properties for the corresponding graft copolymers such as PVC-g-GMA, PVC-g-HEMA, and their crosslinked films were also investigated in this study. The results showed that the tensile strengths for PVC–poly (GMA) blend systems were higher than those for PVC-g-GMA graft copolymer, and the tensile strengths for PVC-g-HEMA were higher than those for PVC-poly (HEMA) blend systems. However, the mechanical properties for the PVC–poly (GMA) blend system were not affected by the crosslinking of the blend system, but those for PVC-poly (HEMA) and their graft copolymers decreased with an increase of the equivalent ratio ([NCO]/[OH]) of the crosslinker. Finally, the surface hydrophilicity of the PVC-g-HEMA graft copolymer and PVC-poly (HEMA) blends were also assessed through measuring the contact angle. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 307–319, 1998     

Synthesis,self‐assembly,and drug release behavior of star‐shaped poly(ε‐caprolactone)‐b‐poly(ethylene oxide) block copolymer with porphyrin core

A serial of star‐shaped poly(ε‐caprolactone)‐b‐poly(ethylene oxide) (SPPCL‐b‐PEO) block copolymers with porphyrin core were successfully synthesized from ring‐opening polymerization (ROP) of ε‐caprolactone (CL) initiated with porphyrin core, followed by coupling reaction with a hydrophilic polymer poly(ethylene oxide) (PEO) shell. The structure of this novel copolymer were synthesized and thoroughly characterized by Nuclear Magnetic Resonance (NMR), Gel Permeation Chromatography (GPC), Fourier Transform Infrared Spectroscopy (FTIR). Notably, the as‐prepared porphyrin‐cored star‐shaped copolymer could self‐assembly into different structures determined by transmission electron microscopy (TEM) and dynamic lighting scattering (DLS), which provides the great potential of using this well‐defined photodynamic therapy material for drug delivery system. Particularly, the doxorubicin‐loaded SPPCL‐b‐PEO nanosphere exhibits property of pH‐induced drug release. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40996.     

Mechanical and barrier properties of nanocrystalline cellulose reinforced poly(caprolactone) composites: Effect of gamma radiation

Nanocrystalline cellulose (NCC) reinforced poly(caprolactone) (PCL) composites were prepared by compression molding. The NCC content varied from 2 to 10% by weight. NCC played a significant role in improving the mechanical properties of PCL. The addition of 5 wt % NCC caused a 62% improvement of the tensile strength (TS) value of PCL films. Similarly, tensile modulus (TM) values were also improved by NCC reinforcement but elongation at break (Eb) values decreased montonically with NCC content. The water vapor permeability (WVP) of PCL was 1.51 g·mm/m²·day·kPa, whereas PCL films containing 5 wt % NCC showed a WVP of 1.22 g·mm/m²·day·kPa. The oxygen transmission rate (OTR) and carbon dioxide transmission rate (CO₂TR) of PCL decreased by 19 and 17%, respectively, with 5 wt % NCC incorporation. It was found that the mechanical and barrier properties of both PCL and PCL‐NCC composites further improved with 10 kGy gamma irradiation treatment. The combination of NCC and radiation significantly increased the TS, TM, and Eb (by 156, 123, and 80%, respectively, compared to untreated PCL). The WVP, OTR, and CO₂TR decreased by 25–35% with respect to untreated PCL. The surface and interface morphologies of the PCL‐NCC composites were studied by scanning electron microscopy and suggested homogeneous distribution of NCC within the PCL matrix. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and characterization of a type of ladder‐like poly(phenyl silsesquioxane) based hybrid star‐shaped copolymer of ε‐caprolactone

Combination of the organic–inorganic hybrid such as silsesquioxane with ε‐caprolactone will lead to materials expected to be environmentally friendly and applicable to biomedical usages. A ladder‐like poly(phenyl silsesquioxane) based hybrid star‐shaped copolymer of ε‐caprolactone was prepared by ring opening polymerization of ε‐caprolactone catalyzed by Sn(Oct)₂ with hydroxyl terminated ladder‐like poly(phenyl silsesquioxane) as initiator. The copolymers were characterized by proton nuclear magnetic resonance (¹H‐NMR), silicon nuclear magnetic resonance (²⁹Si‐NMR), Fourier‐transform infrared spectrometer (FT‐IR), size exclusion chromatography (SEC), thermo gravimetric analysis (TGA), and differential scanning calorimetry (DSC) in detail. Furthermore, the enzymatic degradation property of the copolymers was also investigated. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42335.     

Synthesis of poly(ester amide)s composed of lactic acid and glycolic acid units by the bulk polycondensation of metal halide salts

Thermal polycondensation of the potassium salt of N‐methylchloroacetyl‐6‐aminohexanoic acid (LAHK) was found to be effective in the preparation of a new poly(ester amide) based on lactic acid units with a high yield and a moderate molecular weight. The reaction started in the solid state and proceeded through the formation of potassium chloride salt as the driving force. The use of a monomer having an amide linkage diminished the secondary reactions previously found in the synthesis of polylactide from 2‐halogenopropionates. The polymerization of potassium salt of N‐chloroacetyl‐6‐aminohexanoic acid (GAHK) took place in a similar temperature range as that of the 2‐chloropropionyl derivative; in this way, it was possible to conduct the copolymerization processes. The polymerization kinetics of LAHK and its mixture with GAHK was studied by Fourier transform infrared spectroscopy. The bulk polycondensation reaction was faster for GAHK than for LAHK, but the kinetic differences were not significant enough to prevent copolymerization at a temperature close to 160°C. Therefore, new degradable materials with tuned properties according to the glycolic acid/lactic acid content were obtained. ¹H‐NMR spectroscopy was useful for following the time evolution of the copolymerization process and for determining the final composition. Calorimetric data showed that all of the samples were thermally stable and that decreases in the melting temperature and enthalpy were observed at intermediate compositions. The existence of an eutectic point became proof that effective copolymerization was achieved in the thermal polycondensation process. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43197.     

Synthesis and characterization of maleated poly(3‐hydroxybutyrate)

Graft copolymerization of maleic anhydride (MA) onto poly(3‐hydroxybutyrate) (PHB) was carried out by use of benzoyl peroxide as initiator. The effects of various polymerization conditions on graft degree were investigated, including solvents, monomer and initiator concentrations, reaction temperature, and time. The monomer and initiator concentrations played an important role in graft copolymerization, and graft degree could be controlled in the range from 0.2 to 0.85% by changing the reaction conditions. The crystallization behavior and the thermal stability of PHB and maleated PHB were studied by DSC, WAXD, optical microscopy, and TGA. The results showed that, after grafting MA, the crystallization behavior of PHB was obviously changed. The cold crystallization temperature from the glass state increased, the crystallization temperature from the melted state decreased, and the growth rate of spherulite decreased. With the increase in graft degree, the banding texture of spherulites became more distinct and orderly. Moreover, the thermal stability of maleated PHB was obviously improved, compared with that of pure PHB. Its thermal decomposition temperature was enhanced by about 20°C. In addition, the introduction of the MA group promoted the biodegradability of PHB. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 659–668, 2003     

Synthesis and characterization of poly(ϵ‐caprolactone)–poly(L‐lactide) diblock copolymers with an organic amino calcium catalyst

The quasiliving characteristics of the ring‐opening polymerization of ?‐caprolactone (CL) catalyzed by an organic amino calcium were demonstrated. Taking advantage of this feature, we synthesized a series of poly(?‐caprolactone) (PCL)–poly(L ‐lactide) (PLA) diblock copolymers with the sequential addition of the monomers CL and L ‐lactide. The block structure was confirmed by ¹H‐NMR, ¹³C‐NMR, and gel permeation chromatography analysis. The crystalline structure of the copolymers was investigated by differential scanning calorimetry and wide‐angle X‐ray diffraction analysis. When the molecular weight of the PLA block was high enough, phase separation took place in the block copolymer to form PCL and PLA domains, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2654–2660, 2006     

Composites of poly(lactic acid) with flax fibers modified by interstitial polymerization

Natural fiber composites were designed and optimized to achieve good mechanical properties and resistance to growth of living organisms. Composite materials were prepared from poly(lactic acid) (PLA) with flax fibers, where the flax fibers had been subjected to interstitial polymerization to replace the water in the cellulose fibers. Before polymerization, the flax fibers were extracted with sodium hydroxide and acetone to remove lignin, pectin, and waxes from the cellulose. Differential scanning calorimetry was used to study the crystallization and melting of the composites as compared with pure PLA. The surface wetting of the fibers and morphology of the composites were studied by scanning electron microscopy and optical microscopy. Mechanical properties were studied using dynamic mechanical analysis. The influence of the interstitial polymerization on the dynamic storage modulus was found to be significant. The composites of polymerization treated flax, with acetone washed fibers, had higher storage moduli than the unwashed fiber composites, which suggested adhesion between flax fibers, and the matrix was improved by the treatments. The composites were subjected to moist environmental conditions to test for development of mold and fungi, and the acetone washed polymerization treated flax composites were resistant to these growths. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Composites of poly(lactic acid) with flax fibers modified by interstitial polymerization

Natural fiber composites were designed and optimized to achieve good mechanical properties and resistance to growth of living organisms. Composite materials were prepared from poly(lactic acid) (PLA) with flax fibers, which had been subjected to interstitial polymerization to replace the water in the cellulose fibers. Prior to the polymerization, the flax fibers were extracted with sodium hydroxide and acetone to remove lignin, pectin, and waxes from the cellulose. Differential scanning calorimetry was used to study the crystallization and melting of the composites compared to pure PLA. The surface wetting of the fibers and morphology of the composites were studied by scanning electron microscopy and optical microscopy. Mechanical properties were studied using dynamic mechanical analysis. The influence of the interstitial polymerization on the dynamic storage modulus was found to be significant. The composites of polymerization treated flax with acetone washed fibers had higher storage moduli than the unwashed fiber composites, which suggested that the adhesion between the flax fibers and the matrix was improved by the treatments. The composites were subjected to moist environmental conditions in order to test for development of mold and fungi, and the acetone washed polymerization treated flax composites were resistant to these growths. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3620–3629, 2006