Exploring the synergistic effect of carboxymethyl cellulose and chitosan in enhancing thermal stability of polyurethanes through statistical mixture design approach.

The thermal stability of polyurethanes, known for its limitations, was addressed in this research by seeking improvement through the introduction of carbohydrate-based chain extenders. In this research paper, we systematically sought to improve the thermal resistance of polyurethanes by incorporating carboxymethyl cellulose and chitosan, representing a pioneering application of the mixture design approach in their preparation. In this synthesis, hydroxyl-terminated polybutadiene and isophorone diisocyanate (IPDI) were reacted to prepare -NCO terminated prepolymer, which was subsequently reacted with varying mole ratios of CMC and CSN to develop a series of five PU samples. The prepared PU samples were characterized using the Fourier-transformed infrared spectroscopic technique. Thermal pyrolysis of PU samples was examined using thermal gravimetric analysis (TGA). It was observed that, among all the samples, PUS-3 showed remarkable thermal stability over a wide temperature range. A comprehensive statistical analysis was conducted to substantiate the experimental findings. It was estimated that CMC and CSN significantly enhance the thermal stability of the samples when involved in an interaction fashion. The ANOVA Table for the mixture design demonstrates that over 90 % of the total variation in thermal stability is explained by the mixture model across a wide temperature range. Moreover, PSU-3 exhibited 4 % more thermal stability over a wide range of temperatures on average, as compared to contemporary samples.

Development of lactic acid based chain extender and soybean oil-derived polyurethanes for ecofriendly sustained drug delivery systems.

In the present study, a range of sustainable, biocompatible and biodegradable polyurethanes (PU-1 to PU-4) were synthesized using different combinations of biobased polyol (obtained through the epoxidation of soybean oil, followed by ring opening with ethanol) and polyethylene glycol (PEG) and isophorone diisocyanate. The sustainable chain extender used in this study was synthesized by the esterification of lactic acid with ethylene glycol (EG). The synthesized PU samples were characterized through scanning electron microscopy (SEM), Fourier transformed infrared (FTIR) and nuclear magnetic resonance (1H NMR and 13C NMR) spectroscopy. Wetting ability and thermal degradation analysis (TGA) of the samples were also studied. Subsequently, these PUs were examined as potential drug delivery systems using Gabapentin as a model drug, which was loaded in the polymer matrix using the solvent evaporation method. The drug release studies were carried out in 0.06 N HCl as a release medium according to the method outlined in the United States Pharmacopeia. The maximum drug release was observed for sample PU-P1, which was found to be 53.0 % after 6 h. Moreover, a comparison of different PU samples revealed a trend wherein the values of drug release were decreased with an increase in the PEG content.

Development of biocompatible aqueous polyurethane dispersions using chitosan and curcumin to improve physicochemical properties of textile surfaces.

The present research work aims to synthesize a blend of chitosan (CSN) and curcumin (CRN) based aqueous polyurethane dispersions (CSN-CRN APUDs) for the modification of textile surfaces. A series of anionic CSN-CRN APUDs were prepared by the reaction of isophorone diisocyanate (IPDI) with polyethylene glycol (PEG) and extended with chain extenders (CSN and CRN). Structural characterizations of prepared materials were examined through a fourier transformed infrared (FTIR) spectrophotometer. The performances of coated CSN-CRN APUDs on the colorfastness properties (washing, rubbing and perspiration) and the mechanical properties like tensile strength and tearing strength of plain weaved poly/cellulosic textiles (dyed, printed and white) were examined before and after the application of CSN-CRN APUDs. The findings showed that the mechanical and colorfastness properties of all the CSN-CRN APUDs treated poly/cellulosic textile samples were improved significantly as compared with untreated poly/cellulosic textile samples. The newly synthesized CSN-CRN APUD coating materials are sustainable and greener products, particularly derivatized from bio-resources. These coating materials can be utilized as outstanding eco-friendly substitutes for poly/cellulosic textile coatings for surface modifications.

Development of amylopectin based polyurethanes for sustained drug release studies.

In this research work, the crosslinked structure of polyurethane has been exploited for sustained drug delivery. Polyurethane composites have been prepared by the reaction of isophorone diisocyanate (IPDI) and polycaprolactone diol (PCL), which were further extended by varying the mole ratios of amylopectin (AMP) and 1,4-butane diol (1,4-BDO) chain extenders. The progress and completion of the reaction of polyurethane (PU) were confirmed using Fourier Transform infrared (FTIR) and nuclear magnetic resonance (1H NMR) spectroscopic techniques. Gel permeation chromatography (GPC) analysis showed that the molecular weights of prepared polymers were increased with the addition of amylopectin into the PU matrix. The molecular weight of AS-4 (Mw ≈ 99,367) was found threefold as compared to amylopectin-free PU (Mw ≈ 37,968). Thermal degradation analysis was done using thermal gravimetric analysis (TGA) and inferred that AS-5 showed stability up to 600 °C which was the maximum among all PUs because AMP has a large number of -OH units for linking with prepolymer resulting in a more cross-linked structure which improved the thermal stability of the AS-5 sample. The samples prepared with AMP showed less drug release (<53 %) as compared to the PU sample prepared without AMP (AS-1).

Synthesis and molecular characterization of chitosan/alginate blends based polyurethanes biocomposites.

The present work aims to examine the structural properties of polyurethanes bio-composites with mole ratios of alginate and chitosan. For this concern, a two-step reaction mechanism was carried out; in the first step isocyanate (-NCO) terminated pre-polymer was synthesized by the reaction of hexamethylene diisocyanate (HMDI) and hydroxyl-terminated polybutadiene (HTPB). The pre-polymer was further extended with 1,4-butanediol (BDO), chitosan (CS) and alginate (ALG) in the second step. Structural and functional group elucidation was done by using Fourier Transform Infra-red (FT-IR) and proton nuclear magnetic resonance (1H NMR) spectroscopy. The crystallinity of the prepared samples was investigated by using X-ray diffraction (XRD) method, the maximum observed intensity was 7704 a.u. The thermal properties of polyurethane composites were carried out using thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC). The TGA results showed that thermal stability of RPU-5 was 20 °C more than RPU-1 at each corresponding degradation temperature. It is observed all physical parameters like crystallinity, glass transition temperature, melting point are much dependent on ratio of chain extenders. Overall, CS based samples along with small amount of ALG showed better thermal properties.

Utilization of waxy corn starch as an efficient chain extender for the preparation of polyurethane elastomers.

Waxy corn starch modified polyurethane elastomers were synthesized by step growth polymerization reaction between NCO-terminated prepolymer and chain extenders (1,4-butanediol/starch). Isophorone diisocyanates (IPDI) was reacted with hydroxyl terminated polybutadiene (HTPB) to synthesize prepolymer that was reacted with different moles of 1,4-butanediol (1,4-BDO) and starch to produced five samples of polyurethane. These specimens were analyzed by Fourier transformed infrared (FTIR) and proton Nuclear Magnetic Resonance (1H NMR) spectroscopy to determine the structural information. However, role of starch as chain extender was examined by gel permeation chromatography (GPC). Additionally, starch increased the thermal stability of PUs as compared to the conventional chain extender (1,4-BDO). Over all, this work has been designed to develop biodegradable polyurethanes that could be used in biomedical systems.

Synthesis and molecular characterization of chitosan/starch blends based polyurethanes.

Starch/chitosan modified polyurethanes (PUs) were synthesized by step growth polymerization reaction between -NCO terminated prepolymer and chain extenders (1,4-Butanediol/starch/chitosan). Isophorone diisocyanate (IPDI) was reacted with hydroxyl-terminated polybutadiene (HTPB) to synthesize prepolymer and was further reacted with different moles ratio of starch/chitosan to produced five samples of polyurethane (PU). These samples were characterized by Fourier transformed infrared (FTIR) and Proton nuclear magnetic resonance (1H NMR) spectroscopy. The surface characterizations of PUs were done by scanning electron microscope (SEM). Thermogravimetric analysis showed that the thermal stability of PUs was higher when the mixture of both natural materials was used at equal amounts. It is concluded that combination of both starch and chitosan are efficient for the synthesis of PUs.

Influence of chitosan/1,4-butanediol blends on the thermal and surface behavior of polycaprolactone diol-based polyurethanes.

This current study aims to study of the thermal behavior of the polyurethane elastomers (PUEs) by varying blends of 1, 4-butanediol and chitosan (CS) into the backbone of polyurethane (PU). The polycaprolactone diol (PCL) was used as a macrodiol while a mixture of CS and 1, 4-butanediol was reacted to extend the polymer. For the preparation of NCO-endcapped polyurethane prepolymer; one equivalent of PCL was reacted with three equivalents of toluene diisocyanate (TDI). The obtained pre-polymer was further extended with CS and 1, 4-butanediol (2 mol) individually and with different blends. The characterization of the structure was determined using FTIR and NMR spectroscopy. The glass transition temperature of prepared polyurethanes was measured by differential scanning calorimetry (DSC). The results obtained showed that, the thermal behavior of PUs was enhanced as the CS contents were increased in the PU backbone. The crystalline behavior of CS increased the hydrophobicity of the prepared PUs. Moreover; the water absorption, contact angle, swelling behavior, work of water adhesion and surface free energy of the synthesized PUs were affected with the addition of chitosan. Finally, it has been concluded resultant chitosan based PU has a potential for biomedical implant i.e., non-absorbable suture.

Evaluation of cytotoxicity, hemocompatibility and spectral studies of chitosan assisted polyurethanes prepared with various diisocyanates.

In this research work cytocompatibility, mutagenicity, and hemolytic activity of chitosan-based polyurethanes (PUs) have been evaluated. The chitosan modified PUs were prepared by step-growth polymerization technique using various diisocyanates like isophorone diisocyanate (IPDI). 4,4'-methylenedicyclohexyl diisocyanate (H12MDI), 2,4-toluene diisocyanate (TDI) and hexamethylene diisocyanate (HMDI) by reacting with hydroxyl-terminated polybutadiene (HTPB). Structural confirmation of prepared samples was done by FTIR-ATR and 1H NMR techniques. Chitosan bearing PU samples showed good hemocompatibility, non-mutagenic behavior and less or non-cytotoxic behavior with all the diisocyanates. Among all the diisocyanates, aromatic diisocyanate (TDI) showed less hemocompatibility, high mutagenicity, and more cytotoxicity. However, this still showed a better result than non-chitosan based sample. It is concluded that chitosan improved the biological behavior of PU samples.

Mathematical modeling and experimental study of mechanical properties of chitosan based polyurethanes: Effect of diisocyanate nature by mixture design approach.

This research work has been done to investigate the influence of the geometry of aliphatic diisocyanate (hexamethylene diisocyanate, HDI), cycloaliphatic diisocyanate (isophorone diisocyanate, IPDI) and aromatic diisocyanate (2,4-toluene diisocyanate, TDI) on the tensile strength and hardness of chitosan based polyurethane biomaterials. For this purpose, chitosan (CS) and polycaprolactone diol (PCL) based polyurethanes have been synthesized with above mentioned diisocyanates following statistical design (mixture design). Simplex mixture design was used for analysis and totally 10 experiments were generated by the software. Samples were tested based on the portions of mixture components. Fourier transform Infrared attenuated total reflection (FTIR-ATR) and nuclear magnetic resonance (NMR) spectroscopic techniques confirmed the synthesis of chitosan based polyurethanes. This biomaterial has been established as an innovative and promising strategy to improve the mechanical strength of chitosan-based polyurethanes.

Thermal degradation behavior and X-ray diffraction studies of chitosan based polyurethane bio-nanocomposites using different diisocyanates.

Five different samples of chitosan based polyurethane bio-nanocomposites (PUBNCs) were synthesized by step growth polymerization technique. Five different diisocyanates were used by keeping hydroxyl terminated polybutadiene (HTPB)/1,4-butane diol (1,4-BDO)/chitosan (CS) and montmorillonite (MMT) clay ratios constant (PUR1-PUR5). For comparative studies, PUR-6 was prepared without CS and clay components. Molecular characterizations of polyurethane (PU) films were carried out by FTIR and NMR which was found to have confirmatory evidence of the proposed structures. X-ray diffraction angles (2θ), d-spacing and intensities of chitosan based samples (PUR1-PUR5) and PUR-6 indicated that crystalline behavior of PUBNCs is influenced by varying diisocyanate structures. TGA/DTA results revealed that chitosan increased thermal stability of PU samples; it also enhanced the mechanical strength and decreased the glass transition temperature (Tg) of all the samples. Based on the above mentioned facts this study suggests the best usage of PUs according to the operational and environmental conditions.

Synthesis and characterization of chitosan modified polyurethane bio-nanocomposites with biomedical potential.

A series of chitosan (CS) and montmorillonite (MMT) clay based polyurethane bio-nanocomposites were synthesized by step growth polymerization; reacting hydroxyl terminated polybutadiene (HTPB) and toluene diisocyanate (TDI) to improve thermal and antibacterial properties of polyurethane (PU). Five different PU samples were prepared by varying mole ratio of CS and 1,4-butane diol (from 0 to 2 mol). Structural studies of PUs through FTIR and 1H NMR spectroscopy confirmed the incorporation of CS into the polymer matrix. The scanning electron microscope (SEM) analysis confirmed well dispersion of MMT clay into the PU matrix. Thermogravimetric analysis (TGA) of PUs indicated significant enhancement of thermal stability of PU with addition of CS. Antibacterial properties of PUs were measured by disc diffusion method; showed excellent potential against the selected strains. On the whole, CS showed potential to improve the antibacterial and structural properties of PU significantly; which might be precursor for biological applications.