scholarly journals Synthesis and swelling behavior of polyurethane networks based on hyperbranched polymer

2011 ◽  
Vol 65 (6) ◽  
pp. 637-644 ◽  
Author(s):  
Jasna Dzunuzovic ◽  
Marija Pergal ◽  
Slobodan Jovanovic ◽  
Vesna Vodnik
Keyword(s):  
Ethylene Oxide ◽  
Hyperbranched Polymer ◽  
Chemical Structure ◽  
Crosslinking Agent ◽  
Swelling Behavior ◽  
Hydroxyl Groups ◽  
Hyperbranched Polyester ◽  
Polyurethane Networks ◽  
Methylenediphenyl Diisocyanate ◽  
Step Polymerization

A series of six polyurethane (PU) networks was synthesized from BoltornR hydroxy-functional hyperbranched polyester (HBP) of the second pseudo generation as a crosslinking agent, ?,?- dihydroxy-(ethylene oxide-poly(dimethylsiloxane)-ethylene oxide) (EO-PDMS-EO) and 4,4?- methylenediphenyl diisocyanate, by a two-step polymerization in solution. Each sample of the prepared PUs had different EO-PDMS-EO content. The chemical structure of the synthesized networks was analyzed by FTIR spectroscopy. The influence of the EO-PDMS-EO content and type of the solvent on the swelling behavior of the PUs in 2-propanol and toluene was investigated. During the swelling measurements certain amount of sol fractions was extracted from the PUs by solvents. According to the 1H NMR results, sol fractions are mainly composed of the soluble hyperbranched PU, formed during the polymerization by partial modification of the end hydroxyl groups of HBP with NCO-terminated prepolymer synthesized in the first step of the reaction. Chains of the so reacted prepolymer can then fold back and form cyclic products by reaction of the free -NCO group from the NCO-terminated prepolymer with free -OH group of HBP. As the EO-PDMS-EO content increases the amount of the sol fractions and swelling degree also increased, indicating that networks with lower EO-PDMS-EO content are more crosslinked and have higher solvent resistance.

scholarly journals Poly(urethane-siloxane)s based on hyperbranched polyester as crosslinking agent: Synthesis and characterization

2012 ◽  
Vol 77 (7) ◽  
pp. 919-935 ◽  
Author(s):  
Marija Pergal ◽  
Jasna Dzunuzovic ◽  
Sanja Ostojic ◽  
Miodrag Pergal ◽  
Aleksandra Radulovic ◽  
...  
Keyword(s):  
Ethylene Oxide ◽  
Crosslinking Agent ◽  
Crosslinking Density ◽  
Hyperbranched Polyester ◽  
Scanning Calorimetry ◽  
Polyurethane Networks ◽  
Swelling Studies ◽  
Step Growth ◽  
Step Growth Polymerization ◽  
Two Stages

A series of novel polyurethane crosslinked structures (PUs) was prepared from ?,?-dihydroxy-(ethylene oxide-poly(dimethylsiloxane)-ethylene oxide) (EO-PDMS-EO), 4,4?-methylenediphenyl diisocyanate and Boltorn? hyperbranched polyester of the third pseudo generation. The hydroxyfunctional hyperbranched aliphatic polyester with 26 end groups was used as crosslinking agent. In order to improve the compatibility of all reactants during the synthesis, PU samples were prepared by a step-growth polymerization in two stages in solution. The soft EO-PDMS-EO segment content was varied in the range from 15 to 40 wt.%. The influence of the EO-PDMS-EO content on the swelling behavior, crosslinking density, hardness, thermal and surface properties of the synthesized PUs was investigated. The structure of the synthesized polyurethanes was confirmed by the presence of specific bands in Fourier transform infrared spectra. Swelling studies were carried out to determine the crosslinking density and polyurethane networks with lower EOPDMS- EO content revealed higher crosslinking density. The glass transition temperature of the synthesized PUs, determined by differential scanning calorimetry, slightly increased from 50 to 58?C by decreasing EO-PDMS-EO content as a consequence of higher crosslinking density of samples. The increase of EO-PDMS-EO content leads to the better thermal stability, as it was confirmed by the value of the starting temperature of thermal degradation. The surface of the polyurethane networks became more hydrophobic with increasing EO-PDMS-EO content. The surface morphology of synthesized polyurethanes was analyzed by scanning electron microscopy.

scholarly journals Reactivity of Aliphatic and Phenolic Hydroxyl Groups in Kraft Lignin towards 4,4′ MDI

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2131
Author(s):  
Leonardo Dalseno Antonino ◽  
Júlia Rocha Gouveia ◽  
Rogério Ramos de Sousa Júnior ◽  
Guilherme Elias Saltarelli Garcia ◽  
Luara Carneiro Gobbo ◽  
...  
Keyword(s):  
Experimental Work ◽  
Chemical Structure ◽  
31P Nmr ◽  
Kraft Lignin ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Diphenylmethane Diisocyanate ◽  
Complex Chemical ◽  
Heterogeneous Reactivity ◽  
Phenolic Hydroxyl Groups

Several efforts have been dedicated to the development of lignin-based polyurethanes (PU) in recent years. The low and heterogeneous reactivity of lignin hydroxyl groups towards diisocyanates, arising from their highly complex chemical structure, limits the application of this biopolymer in PU synthesis. Besides the well-known differences in the reactivity of aliphatic and aromatic hydroxyl groups, experimental work in which the reactivity of both types of hydroxyl, especially the aromatic ones present in syringyl (S-unit), guaiacyl (G-unit), and p-hydroxyphenyl (H-unit) building units are considered and compared, is still lacking in the literature. In this work, the hydroxyl reactivity of two kraft lignin grades towards 4,4′-diphenylmethane diisocyanate (MDI) was investigated. 31P NMR allowed the monitoring of the reactivity of each hydroxyl group in the lignin structure. FTIR spectra revealed the evolution of peaks related to hydroxyl consumption and urethane formation. These results might support new PU developments, including the use of unmodified lignin and the synthesis of MDI-functionalized biopolymers or prepolymers.

scholarly journals Synthesis of Novel Crosslinked Chitosans with a Higher Fatty Diacid Diglycidyl and Their Adsorption Abilities towards Acid Dyes

2003 ◽  
Vol 21 (5) ◽  
pp. 439-449 ◽  
Author(s):  
Yoshiaki Shimizu ◽  
Atsushi Taga ◽  
Hitoshi Yamaoka
Keyword(s):  
Chemical Structure ◽  
Crosslinking Agent ◽  
Considerable Extent ◽  
Degree Of Substitution ◽  
Acid Orange 7 ◽  
Acid Dyes ◽  
Ph Values ◽  
Crosslinked Chitosan ◽  
Adsorbent Materials ◽  
Dye Molecule

Novel chitosan-based adsorbent materials with a higher fatty diacid diglycidyl as the crosslinking agent were synthesized and the adsorption abilities of the resulting polymers evaluated towards typical acid dyes. The successful formation of a crosslinked structure was confirmed via infrared spectroscopic measurements and the solubility of the polymer towards 10% aqueous solutions of acetic and formic acids determined. At higher dye concentrations, the adsorption abilities of the crosslinked chitosan towards hydrophilic CI Acid Orange 7 and CI Acid Red 1 increased with decreasing degree of substitution. However, at lower dye concentrations, the crosslinked chitosan with the lowest degree of substitution exhibited the lowest adsorption capability. With such hydrophilic acid dyes, the extent of adsorption decreased significantly as the pH of the solution increased. On the other hand, CI Acid Red 138, which contains a dodecyl group in the chemical structure, was adsorbed to a considerable extent even at higher pH values, suggesting hydrophobic interaction between the alkyl group in the dye molecule and the hydrophobic crosslinker.

scholarly journals Study on the morphology and thermomechanical properties of poly(urethane-siloxane) networks based on hyperbranched polyester

2013 ◽  
Vol 67 (6) ◽  
pp. 871-879
Author(s):  
Marija Pergal ◽  
Jasna Dzunuzovic ◽  
Milena Spírková ◽  
Rafal Poręba ◽  
Milos Steinhart ◽  
...  
Keyword(s):  
Ethylene Oxide ◽  
Microphase Separation ◽  
Soft Segment ◽  
Hydrophobic Surface ◽  
Crosslinking Density ◽  
Thermomechanical Properties ◽  
Hyperbranched Polyester ◽  
Force Microscopy ◽  
X Ray Scattering ◽  
Atomic Force

Two series of polyurethane films based on hyperbranched polyester of the second pseudogeneration (Boltorn?), 4,4'-methylenediphenyl diisocyanate and two different siloxane prepolymers, ?,?-dihydroxy-(ethylene oxide-poly(dimethylsiloxane)-ethylene oxide) (EO-PDMS-EO) and ?,?-dihydroxypropyl-poly(dimethylsiloxane) (HP-PDMS), were prepared by two-step polymerization in solution. The influence of the type and content of soft segment on the morphology, thermomechanical and surface properties of the synthesized polyurethanes was studied by atomic force microscopy (AFM), small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM), dynamic mechanical thermal analysis (DMTA) and water absorption measurements. It was found that these techniques confirmed existence of microphase separated morphology. Synthesized polyurethanes exhibited two glass transition temperatures and one second relaxation process. The results showed that polyurethanes based on HP-PDMS had higher surface roughness, better microphase separation and waterproof performances. Samples synthesized with lower PDMS content had less hydrophobic surface, but higher crosslinking density and better thermomechanical properties. (Projekat Ministarstva nauke Republike Srbije, br. 172062]

Polyurethane networks based on polycaprolactone and hyperbranched polyester: Structural, thermal and mechanical investigation

2019 ◽  
Vol 137 ◽  
pp. 105305 ◽  
Author(s):  
Jasna V. Džunuzović ◽  
Ivan S. Stefanović ◽  
Enis S. Džunuzović ◽  
Aleksandra Dapčević ◽  
Sanja I. Šešlija ◽  
...  
Keyword(s):  
Hyperbranched Polyester ◽  
Polyurethane Networks ◽  
Mechanical Investigation

Preparation of Antibacterial Cotton Fabric Containing Patchouli Oil Microcapsules by Chemical Crosslinking Method

2011 ◽  
Vol 221 ◽  
pp. 308-315 ◽  
Author(s):  
Zi Ming Yang ◽  
Gen Quan Liang ◽  
Ly Li ◽  
Wai Man Au ◽  
Hui Yi Zhong ◽  
...  
Keyword(s):  
Cotton Fabric ◽  
Crosslinking Agent ◽  
Antibacterial Properties ◽  
Infrared Spectrometry ◽  
Hydroxyl Groups ◽  
Chemical Crosslinking ◽  
Complex Coacervation ◽  
Persistent Effect ◽  
Butanetetracarboxylic Acid

In this paper, a new kind of antibacterial cotton fabric containing patchouli oil microcapsules was investigated. The patchouli oil microcapsules were prepared using a complex coacervation procedure and grafted onto cotton fabric by chemical crosslinking method, along with 1,2,3,4-butanetetracarboxylic acid (BTCA) was utilized as the crosslinking agent. The surface and morphology of fabrics were characterized by using scanning electron microscope (SEM). Fourier transform infrared spectrometry (FTIR) was used to study the formation of ester bonds between BTCA and hydroxyl groups of cotton and patchouli oil microcapsules. The releasing characteristics and antimicrobial durability of the antibacterial fabrics were also investigated by releasing test and laundering test. The results showed that the patchouli oil microcapsules were grafted onto cotton fabric by the role of crosslinking agent BTCA and the treated fabric represented persistent effect, slow releasing performance and washable antibacterial properties. After 30 days, the patchouli oil in the microcapsules was still remained on the fabric and the releasing amount was near 50%. About 72% antibacterial rate of the fabric for staphylococcus aureus and candida albicans could be obtained after washed 30 times, furthermore, no formaldehyde releasing can be found. It is suggested that chemical crosslinking method would provide a potential application in functional finishing by microcapsules for cotton fabric.

Synthesis and Characterization of Carboxyl-Terminated Hyperbranched Polyester

2014 ◽  
Vol 665 ◽  
pp. 327-330
Author(s):  
Shi Jie Niu ◽  
Jian Wang ◽  
Yu Qing Bai ◽  
Ming Tao Run
Keyword(s):  
Glass Transition ◽  
Sodium Acetate ◽  
Succinic Anhydride ◽  
Molar Ratio ◽  
Synthesis And Characterization ◽  
Hydroxyl Groups ◽  
Hyperbranched Polyester ◽  
End Groups ◽  
Lower Glass Transition Temperature

In order to prepare carboxyl-terminated hyperbranched polyester (HBP-COOH), succinic anhydride was used to modify hydroxyl-terminated hyperbranched polyester (HBP-OH), and the influences of the solvents, catalysts and time on the product’s structure were investigated. When THF is used as the solvent, sodium acetate as the catalyst, the molar ratio of succinic anhydride and hydroxyl groups is 3:1, and the reaction time is 6 h at 65°C, the modification extent of the hydroxyl groups is about 99% with about 95% yield. HBP-COOH has much lower glass transition temperature than that of HBP-OH due to its long and flexible end-groups.

Studies of molecular dynamics in polyurethane networks with hyperbranched polyester Boltorn®H30 as a crosslinker

2007 ◽  
Vol 353 (47-51) ◽  
pp. 4293-4297 ◽  
Author(s):  
Lidia Okrasa ◽  
Przemyslaw Czech ◽  
Gisèle Boiteux ◽  
Francoise Méchin ◽  
Jacek Ulanski
Keyword(s):  
Molecular Dynamics ◽  
Hyperbranched Polyester ◽  
Polyurethane Networks
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