Bio-degradable vegetable oil based hyperbranched poly(ester amide) as an advanced surface coating material

Vegetable oil based hyperbranched poly(ester amide) (HBPEA) has enormous importance because of its unique characteristics. Thus the synthesis of HBPEA using N,N′-bis(2-hydroxy ethyl) castor oil fatty amide, maleic anhydride, phthalic anhydride and isophthalic acid as A₂ monomers and diethanol amine, as B₃ monomer was reported for the first time. The chemical structure of the synthesized resin was characterized by Fourier transform infrared (FTIR) and nuclear magnetic resonance (¹H NMR and ¹³C NMR) spectroscopic techniques. The degree of branching (DB) (as vouched by ¹H NMR analysis) and initial degradation temperature were found to increase with the increment in B₃ monomer content. Resins with 5 and 10 wt% of B₃ monomer showed shear thinning behavior while rheopectic nature of HBPEA with 15 wt% of B₃ content was observed. The evaluation of tensile strength, elongation at break, abrasion resistance, adhesion strength, scratch hardness, gloss, impact strength and chemical resistance complemented by microbial and lipolytic degradation forward the epoxy cured thermosets as advanced biodegradable surface coating materials.     

Castor oil-based hyperbranched polyurethanes as advanced surface coating materials

21st Century is treated as the century for highly branched macromolecules, because of their unique structural architecture and outstanding performance characteristics, in the field of polymer science. In the present study, castor oil-based two hyperbranched polyurethanes (HBPUs) were synthesized via A₂ + B₃ approach using castor oil or monoglyceride of the castor oil as the hydroxyl containing B₃ reactant and toluene diisocyanate (TDI) as an A₂ reactant along with 1,4-butane diol (BD) as the chain extender and poly(?-caprolactone) diol (PCL) as a macroglycol. The adopted ‘high dilution and slow addition’ technique offers hyperbranched polymers with high yield and good solubility in most of the polar aprotic solvents. Fourier transforms infra-red spectroscopy (FTIR) and nuclear magnetic resonance (NMR) analyses confirmed the chemical structure of synthesized polymers, while wide angle X-ray diffraction (WXRD) and scanning electron microscope (SEM) resulted the insight of their physical structures. The degree of branching was calculated from ¹H NMR and found to be 0.57 for castor oil based hyperbranched polyurethane (CHBPU), while it was 0.8 for monoglyceride based hyperbranched polyurethane (MHBPU). The studies showed that MHBPU and CHBPU exhibited tensile strength 11 MPa and 7 MPa, elongation at break 695% and 791%, scratch hardness 5 kg and 4.5 kg, gloss 84 and 72, respectively. Thermal properties like thermo stability, melting point, enthalpy, degree of crystallinity and glass transition temperature (T_g); and chemical resistance in different chemical media were found to be almost equivalent for both the polyurethanes. The measurements of dielectric constant and lost factor indicated that both the HBPUs behave as dielectric materials. Thus the synthesized HBPUs have the potential to be used as advanced surface coating materials.     

Novel hyperbranched poly(phenylene oxide)s with phenolic terminal groups: synthesis, characterization, and modification

Novel hyperbranched poly(phenylene oxide)s (HPPOs) with phenolic terminal groups were prepared from 4-bromo-4′,4″-dihydroxytriphenylmethane via a modified Ullmann reaction. This monomer was treated with potassium carbonate or sodium hydroxide as a base and copper chloride as a catalyst in an aprotogenic solvent, either dimethylsulphoxide (DMSO) or sulfolane. The sulfolane/NaOH system at higher temperature led to more rapid polymerization, and a relative high molecular weight. The degrees of branching of these HPPOs from the DMSO/K₂CO₃ and sulfolane/NaOH systems were 71 and 48%, respectively, as determined by ¹H NMR integration experiments. The phenolic terminal groups underwent facile modification, furnishing hyperbranched polymers with a variety of functional chain ends. The nature of the chain-end groups had a significant influence on the solubility of the hyperbranched poly(phenylene oxide)s. The resulting polymers were characterized by NMR, Fourier transform infrared, gel permeation chromatography (GPC), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC).     

Stepwise surface modification of mesoporous silica and its use in poly(urethane-urea) composite films

The compatibility between polymer matrix and filler is a vital issue in the fabrication of composites with desirable properties. To enhance the interfacial adhesion between matrix and filler, various surface modification treatments are applied. The objective of this study was to increase the affinity of silica and poly(urethane-urea)s (PUUs), thereby improving the mechanical properties of the resulting composites. Stepwise surface modification of mesoporous silica with amine-containing dendrimers was done. Various techniques were used to confirm the surface-modified structure during the stepwise reaction. Additionally, the N₂ adsorption–desorption method indicated a gradual reduction in surface area, pore diameter and pore volume of the particles, which warrants the gradual propagation of the dendrimers on the surface and also inside the pores. A type IV isotherm was obtained in this analysis. Two types of pre-synthesized PUUs were chosen for composite preparation containing the surface-modified silica with 0.5, 1, 2.5 and 5 wt% concentrations. Due to the high affinity of the dendrimers containing amine moieties on the particles with polyurethane, a proper dispersion of particles in the matrix was achieved based on scanning electron micrographs. Tensile measurements showed an increased Young's modulus and strength of polyurethane films as a result of addition of the particles. However, no significant improvement in the tensile performance of the composites was seen above 2.5 wt% particle loading due to some particle aggregations. © 2021 Society of Industrial Chemistry.     

Postgrafting of vinyl polymers onto hyperbranched poly(amidoamine)-grafted nano-sized silica surface

To prepare polymer-grafted nano-sized silica with hydrophilic core and hydrophobic shell and with higher percentage of grafting, the postgraft polymerization of vinyl polymers onto hyperbranched poly(amidoamine)-grafted (PAMAM-grafted) nano-sized silica initiated by the system consisting of Mo(CO)₆ and terminal trichloroacetyl groups of PAMAM-grafted silica was investigated. The introduction of trichloroacetyl groups onto PAMAM-grafted silica surfaces was readily achieved by the reaction of trichloroacetyl isocyanate with terminal amino groups of PAMAM-grafted silica. It was found that the polymerization of vinyl monomers, such as methyl methacrylate (MMA), styrene, and glycidyl methacrylate (GMA) was successfully initiated by the system consisting of Mo(CO)₆ and terminal trichloroacetyl groups of PAMAM-grafted silica. In the polymerization, the corresponding vinyl polymers were effectively postgrafted onto PAMAM-grafted silica, based on the propagation of polymer from surface radicals formed by the reaction of terminal trichloroacetyl groups with Mo(CO)₆: the percentage of PMMA postgrafting onto PAMAM-grafted silica reached to 400% after 30 min, but the formation of gel was observed after 35 min. The formation of gel tends to decrease by use of hyperbranched PAMAM-grafted silica with higher percentage of grafting. The vinyl polymer-postgrafted nano-sized silica gave a stable colloidal dispersion in various organic solvents.     

Effect of chain extender on microphase structure and performance of self-healing polyurethane and poly(urethane-urea)

In this work, four aliphatic chain extenders, hexanediol (HDO), hexane diamine (HDA), cystamine (CY), and cystine dimethyl ester (CDE), were chosen to synthesize four kinds of polyurethane and poly(urethane-urea)s (PUs), respectively. HDO extended polyurethanes, HDA extended poly(urethane-urea), CY extended poly(urethane-urea), and CDE extended poly(urethane-urea) were denoted as OPU, APU, CPU, and SPU, respectively. The effect of chain extender type on microphase structure and performance of four PUs was investigated. Our research showed that mechanical strength increased in the following order: OPU < SPU < CPU < APU, and self-healing performance increased in the opposite direction. This result is attributed to the increasing degree of microphase separation: OPU < SPU < CPU < APU. The optimal sample SPU has not only excellent mechanical properties (tensile strength of 27.1 MPa and elongation at break of 397.7%), but also exhibits superior self-healing performance (self-healing efficiencies of 95.3% and 93.5% based on tensile strength and elongation at break). The moderate degree of microphase separation between the soft segments and the hard segments, the introduction of disulfide bonds and low degree of hydrogen bonding are responsible for preparing a polyurethane or poly(urethane-urea) system with high mechanical strength and excellent self-healing performance simultaneously. This work provides useful information for us to develop self-healing polyurethane or poly(urethane-urea) materials in the future.     

Phosphorus based indole and imidazole functionalized hyperbranched polyester as antimicrobial surface coating materials

Third generation of hyperbranched polyester (HP) synthesized via melt condensation and end-capped with bis indole and imidazole phosphoryl chloride. The modified polyesters subjected to different characterization viz., FTIR, ¹H and ¹³C NMR, GPC and elemental analysis. NMR analysis was used for the determination of OH conversion that demonstrates linear units had a lower reactivity as compared to terminal OH groups in HP. The thermogravimetric analysis (TGA) and differential scanning calorimetric (DSC) studies indicated that the HP was stable up to 276 °C and the glass transition temperature was 79.6 °C. After modification of HP, thermal stability was increased for indole modified HP, but the glass transition temperature was decreased. The flame retardance of the hyperbranched polyester was also evaluated with the help of TGA analysis and showed higher value of limiting oxygen index (LOI) for modified polyesters. Morphology of the modified polyester showed more roughness than unmodified HP and this nature positive correlated with bacterial zone of inhibition value. Biological studies showed that the HP and modified HP are able to inhibit the reproduction of gram-positive and gram-negative bacteria. Indole modified HP is showed good activity compared to imidazole modified HP.     

Synthesis and properties of semi-crystalline hyperbranched poly(ester-amide) grafted with long alkyl chains used for UV-curable powder coatings

A series of semi-crystalline hyperbranched poly(ester-amide)s by modifying hydroxyl end groups of hyperbranched poly(ester-amide) (HP) with IPDI-C18 and IPDI-HEA in different ratios were synthesized and characterized by FTIR, NMR and GPC. Their crystallization behaviors and thermal properties determined by X-ray diffraction (XRD) and differential scanning calorimetry (DSC) showed that the high substitution degree of hydroxyl groups of hyperbranched poly(ester-amide) (HP) with IPDI-C18 resulted in higher degree of crystallization and thus glass transition temperature (T_g) up to 43 °C. The photopolymerization kinetics investigated by photo-DSC showed that the obtained semi-crystalline hyperbranched resins have high photopolymerization rate and final unsaturation conversion, which is very promising for UV-curable powder coating applications.     

In situ grafting of carboxylic acid-terminated hyperbranched poly(ether-ketone) to the surface of carbon nanotubes

Carboxylic acid-terminated hyperbranched poly(ether-ketone)s (HPEKs) were successfully grafted onto the surfaces of single-walled carbon nanotube (SWNT) and multi-walled carbon nanotube (MWNT) to afford HPEK-g-SWNT and HPEK-g-MWNT nanocomposites. They were prepared via in situ polymerization of 5-phenoxyisophthalic acid as an AB₂ monomer for the HPEK in the presence of SWNT or MWNT in polyphosphoric acid (PPA)/phosphorous pentoxide (P₂O₅) medium. The resultant nanocomposites were homogeneously dispersed in various common polar aprotic solvents as well as in concentrated ammonium hydroxide. The experimental results from Soxhlet extraction, solubility enhancement, elemental analysis (EA), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) provided clear evidences for grafting of hyperbranched polymers onto the surfaces of corresponding CNT's. Achieving enhanced solubility of CNT's in common organic solvents via the functionalization of CNT's is a key step for CNT's to be used in various application-specific purposes. The results could potentially envision to the area of CNT researches via the efficient introduction of three-dimensional globular dendritic macromolecules as increasing solubility, available multi-functionality, reactivity, processability, and also biocompatibility.     

Novel dendritic-poly(urethane-urea) hybrid thin films from hydrogen bond rich dendrons

Hydrogen bond rich segmented poly(urethane-urea) was synthesized from methylene diphenylisocyanate (MDI) and three generations of polyurea-malonamide dendrons as hard segment and polycaprolactone diol as soft segment for thin film applications. The prepared polymers were characterized using spectroscopic, microscopic and thermal analyses. The formation of urethane linkage during the prepolymer reaction and the urea linkage between prepolymer and the dendrons is confirmed by Fourier transform infrared (FTIR) spectroscopy and ¹H nuclear magnetic resonance (NMR) spectroscopy. FTIR shows the presence of hydrogen bonding of –NH groups with both urethane carbonyl group from hard segment and the ether group from the soft segment. However, the phase mixing of hard and soft segments decreases with the higher generation dendrons, as evidenced from FTIR. This observation was confirmed by phase images of the atomic force microscopy (AFM). The coating when applied to clean steel substrates via dip coating reveals uniform, dense and essentially defect free morphology. The work demonstrates that the mechanical properties of the hybrid thin films are dependent on the generation of the dendrons and provides a platform for surface engineering with tunable elastic modulus.     

改性超支化聚（胺-酯）对亚硝酸根的吸附性能研究

以十八烷基三氯硅烷对超支化聚（胺-酯）进行改性,合成了改性的超支化聚（胺-酯）。改性的超支化聚（胺-酯）是一种既具有大量的端羟基且易从中水中分离出来的超支化聚（胺-酯）。将改性的超支化聚（胺-酯）用于吸附亚硝酸根离子,实验结果表明：改性的超支化聚合物对亚硝酸根离子的最大吸附量可达149．7mg／g,在酸性溶液中吸附量还将大大增加。     

Application of thermal methods in the characterisation of poly(urethane-urea)s formed by reaction injection moulding

Differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) have been used in conjunction with tensile testing and transmission electron microscopy (TEM) to characterise novel segmented poly(urethane-urea) (PUU) network materials formed by reaction injection moulding (RIM). Materials were based on a modified liquid 4,4′-diphenylmethane diisocyanate and a polyether triol in admixture with one of three hindered aromatic diamines: 3,5-diethyltoluene diamine (DETDA); methylene-bis-2,6-diisopropylaniline (MMIPA); methylene-bis-(2-methyl-6-isopropylaniline) (MMIPA). The materials ranged from tough translucent elastomers to opaque brittle plastics depending on the chemical nature and weight fraction of the hard segments (HS). DSC and DMTA studies showed the PUU materials to be phase-separated; this was confirmed by TEM and tensile testing. The soft-segment glass transition temperatures (DSC and DMTA) were independent of composition but varied with diamine structure. Hard-segment glass transition temperatures could only be evaluated by DMTA and no evidence of crystallinity was found by thermal methods or by wide angle x-ray diffraction. Heat capacity measurements and DMTA suggested that some degree of phase mixing had occurred, to a greater extent in the DETDA and MDIPA systems. Phase inversion was observed by DMTA and confirmed at ～55% hard-segment content for DETDA systems by tensile testing.     

改性聚乙烯醇添加酒糟制备缓释肥包膜材料的表征及其性能

采用聚乙烯吡咯烷酮（PVP）,通过溶液共混的方式对聚乙烯醇（PVA）进行改性,添加酒糟（JZ）制备复合包膜材料,并对氮肥进行包膜制备缓释肥料。研究了JZ的添加量对复合包膜材料性能以及包膜肥料缓释性能的影响。结果表明：JZ与各组分之间通过氢键作用相互结合,相容性良好;JZ的添加使复合膜材料热稳定性得到了显著提高;120d PUPZ5复合包膜材料降解率相比未添加JZ提高了20.11%;随着JZ的加入,复合包膜材料的机械性能先增加后下降,当JZ与PVA的质量比为15∶100时复合膜材料的力学性能达到了20.75MPa,比未添加酒糟提高了528.79%,且缓释肥料具有良好的缓释性能,可以通过调节JZ在复合包膜材料中的含量来控制缓释肥料中N的释放速率。     

Synthesis and characterization of hyperbranched poly(silyl ester)s

Hyperbranched poly(silyl ester)s were synthesized via the A₂ + B₄ route by the polycondensation reaction. The solid poly(silyl ester) was obtained by the reaction of di‐tert‐butyl adipate and 1,3‐tetramethyl‐1,3‐bis‐β(methyl‐dicholorosilyl)ethyl disiloxane. The oligomers with tert‐butyl terminal groups were obtained via the A₂ + B₂ route by the reaction of 1,5‐dichloro‐1,1,5,5‐tetramethyl‐3,3‐diphenyl‐trisi1oxane with excess amount of di‐tert‐butyl adipate. The viscous fluid and soft solid poly(silyl ester)s were obtained by the reaction of the oligomers as big monomers with 1,3‐tetramethyl‐1,3‐bis‐β(methyl‐dicholorosilyl)ethyl disiloxane. The polymers were characterized by ¹H NMR, IR, and UV spectroscopies, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The ¹H NMR and IR analysis proved the existence of the branched structures in the polymers. The glass transition temperatures (T_g's) of the viscous fluid and soft solid polymers were below room temperature. The T_g of the solid poly(silyl ester) was not found below room temperature but a temperature for the transition in the liquid crystalline phase was found at 42°C. Thermal decomposition of the soft solid and solid poly(silyl ester)s started at about 130°C and for the others it started at about 200°C. The obtained hyperbranched polymers did not decompose completely at 700°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3430–3436, 2006     

Kinetics of the thermal degradation of hyperbranched poly(phenylene sulfide)

An advanced heat‐resistant hyperbranched poly(phenylene sulfide) (HPPS) had been subjected to dynamic thermogravimetric analysis (TGA) in nitrogen. The presence of a single peak in the DTG cures suggested that weight loss occurs in a single stage. The thermal decomposition kinetics had been analyzed by applying the Kissinger, Friedman and Ozawa‐Flynn methods. The E values determined for the hyperbranched PPS using these analyses were found to be 183.1, 189.2, 193.9 kJ mol^?1, respectively. Coats‐Redfern method was used to discuss the probable degradation mechanisms. The solid‐state decomposition mechanism followed by the degradation stage of HPPS was Phase boundary controlled mechanism (R₁). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Biodegradable polymer blends of poly(lactic acid) and poly(ethylene glycol)

Poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG) were melt-blended and extruded into films in the PLA/PEG ratios of 100/0, 90/10, 70/30, 50/50, and 30/70. It was concluded from the differential scanning calorimetry and dynamic mechanical analysis results that PLA/PEG blends range from miscible to partially miscible, depending on the concentration. Below 50% PEG content the PEG plasticized the PLA, yielding higher elongations and lower modulus values. Above 50% PEG content the blend morphology was driven by the increasing crystallinity of PEG, resulting in an increase in modulus and a corresponding decrease in elongation at break. The tensile strength was found to decrease in a linear fashion with increasing PEG content. Results obtained from enzymatic degradation show that the weight loss for all of the blends was significantly greater than that for the pure PLA. When the PEG content was 30% or lower, weight loss was found to be primarily due to enzymatic degradation of the PLA. Above 30% PEG content, the weight loss was found to be mainly due to the dissolution of PEG. During hydrolytic degradation, for PLA/PEG blends up to 30% PEG, weight loss occurs as a combination of degradation of PLA and dissolution of PEG. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1495–1505, 1997     

超支化聚(酰胺-酯)的合成与改性

以邻苯二甲酸酐和二乙醇胺为原料,制得AB2型单体;加入三羟甲基丙烷为核,采用一步法合成了超支化聚(酰胺-酯),并用硬脂酸对所得聚合物进行封端改性.应用红外光谱对改性前后超支化聚合物进行了表征.结果表明,所合成的聚合物与理论结构相吻合,且硬脂酸与端羟基发生了酯化反应,成功地接到了聚合物上.     

Upgrading the adhesion properties of a fast‐curing epoxy using hydrophilic/hydrophobic hyperbranched poly(amidoamine)s

A homologous series of hyperbranched polymers (HBPs) was prepared following a well‐defined method and their formation in a polymeric form bearing different extents of branching with amine functional groups at the terminals was verified using different techniques such as Fourier Transform Infrared, ¹H Nuclear Magnetic Resonance, Differential Scanning Calorimetry, and Gel Permeation Chromatography. Toughening of a commercially available fast cure epoxy was aimed through reactive blending with the formed HBPs that exhibit variation in polarity and branching according to the relevant synthesis strategy employed for each polymer. The mechanical properties (impact resistance, pull‐off adhesion, and bending) of the resulting coating films pertaining to each epoxy formulation after adhering to metal substrates revealed obvious progress in their performance with respect to a control sample that was hardened exclusively in absence of any HBP. The results were explained on the light of the ability of this class of materials to impose flexibility and dilute the intensive crosslink density associated frequently with the rapid curing of epoxy systems. The extent of gained enhancement for each formulation was accounted for by the molecular architecture of the HBPs, their degrees of branching, polarity, and relative reactive contents of primary amino groups in each case. In addition, the influence of these parameters on a proper wetting over the substrate and morphology of the films in each case was also studied using scanning electron microscopy. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and performance of CdS-hyperbranched poly(arylene ether ketone) nanocomposite materials

A new kind of CdS-hyperbranched poly (arylene ether ketone) (HP-PAEK) nanocomposite was prepared in dimethylformamide solution by carboxylic-functionalised HP-PAEK as surface modifier without ligand exchange. The CdS/HP-PAEK nanocomposites were characterised through ultraviolet–visible and photoluminescence spectroscopy. The experimental results of photoluminescence measurement showed that the nanocomposites had obvious luminescence properties. The formation and size of CdS quantum dots were determined by Fourier transform infrared spectroscopy and transmission electron microscopy. The thermal properties of CdS/HP-PAEK nanocomposites were analysed by differential scanning calorimetry and thermogravimetric analysis. Owing to the introduction of CdS nanoparticles, the nanocomposites exhibited excellent heat resistance and higher fluorescent quantum efficiency.     

Biodegradability of poly(ethylene terephthalate) copolymers with poly(ethylene glycol)s and poly(tetramethylene glycol)

Poly(ethylene terephthalate) copolymers were prepared by melt polycondensation of dimethyl terephthalate and excess ethylene glycol with 10–40mol% (in feed) of poly(ethylene glycol) (E) and poly(tetramethylene glycol) (B), with molecular weight (MW) of E and B 200–7500 and 1000, respectively. The reduced specific viscosity of copolymers increased with increasing MW and content of polyglycol comonomer. The temperature of melting (T_m), cold crystallization and glass transition (T_g) decreased with the copolymerization. T_m depression of copolymers suggested that the E series copolymers are the block type at higher content of the comonomer. T_g was decreased below room temperature by the copolymerization, which affected the crystallinity and the density of copolymer films. Water absorption increased with increasing content of comonomer, and the increase was much higher for E1000 series films than B1000 series films. The biodegradability was estimated by weight loss of copolymer films in buffer solution with and without a lipase at 37°C. The weight loss was enhanced a little by the presence of a lipase, and increased abruptly at higher comonomer content, which was correlated to the water absorption and the concentration of ester linkages between PET and PEG segments. The weight loss of B series films was much lower than that of E series films. The abrupt increase of the weight loss by alkaline hydrolysis is almost consistent with that by biodegradation.