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Guar gum (plant-based polysaccharide) is a promising candidate with immense potential. It is used as emulsifier, thickener, stabilizer, and as binding agent in many industries. In the present project, it was planned to synthesize guar gum based polyurethanes by varying the amount of guar gum. Guar gum (GG) was used along with hydroxyl-terminated polybutadiene (HTPB) as soft segment, which was then reacted with isophorone diisocyanate (IPDI) to form PU pre-polymers. In last step, these -NCO terminated pre-polymers were extended with 1,4 butane diol as chain extender. The prepared polyurethane samples were then characterized by using FTIR, solid-state 1 HNMR and X-ray diffraction (XRD). Thermal behavior of the samples was studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Results indicated that the incorporation of guar gum in PU backbone improved its thermal behavior and crystallinity., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Bionanocomposites is an emerging class of biohybrid materials, have a significant impact in environmental and biomedical fields owing to their high performance, lightweight, unique, and ecofriendly properties. A major challenge in the multiphase bionanocomposites system is to subtle control over the performance by managing the individual properties of reacting components. Herein, we presented the preliminary investigation on bionanocomposite system based on graphene nanoplatelets (GNPs) and hydroxyethyl cellulose graft poly(lactic acid) copolymer-polyurethane (HLAC-PU) with the aim to understand the structure property correlation for proposed applications in electronics and medical areas. The HLAC was fabricated by graft copolymerization of hydroxyethyl cellulose (HEC) and lactic acid (LA) with dibutyltin dilaurate. The HLAC was used to get a bio-functionalized PU matrix reinforced with GNPs by step-growth polymerization method. The structural, surface, and thermal properties of the HLAC and GNPs-HLAC-PU bionanocomposites were studied. The spectroscopic techniques confirmed the structure of bionanocomposites by the identification of related bands. The SEM/EDX results demonstrated that the 0.3 wt% of GNPs dispersed well in the HLAC-PU matrix and offered higher crystallinity. The reinforcement of the 0.3 wt% of GNPs has meaningfully enhanced the thermal stability producing higher residue contents. The reinforced GNPs filler increased the water resistance of bionanocomposites by reducing their water vapor permeability., (Copyright © 2020 Elsevier B.V. All rights reserved.)

2-Hydroxyethyl cellulose graft polylactic acid copolymer (HLAC) was prepared by graft copolymerization of lactic acid (LA) and 2-hydroxyethyl cellulose (2-HEC), initiated by dibutyltin dilaurate (DBTDL) catalyst in aqueous media. Halloysite nanotubes (HNTs)/polyurethane (PU) bionanocomposites were prepared using the HLAC as chain extender in the step-growth polymerization. HNTs were dispersed in HLAC based PU matrix at different weight ratios of 0.30, 0.50, 1.00, and 3.00. Chemical structure and morphology of the graft copolymer and bionanocomposite elastomers were characterized using solid state 1 H NMR, ATR-FTIR, XRD, and SEM-EDX, while thermal degradation behavior was studied by TGA and DSC techniques. Surface morphology of the HNTs reinforced HLAC/PU bio-nanocomposites demonstrated the homogeneous dispersion of HNTs with little wavy rough surface at low contents which turned to be brittle at higher contents due to agglomerated HNTs. It is observed that the lower contents of HNTs were completely exfoliated in the HLAC/PU matrix. Crystalline pattern of the elastomers improved at lower contents of HNTs that enhanced the thermal stability of the bionanocomposites. The mechanical testing suggested that HNTs/HLAC/PU bionanocomposites have higher values of tensile strength and % elongation with only 0.3-0.5 wt% contents of HNTs that suggested the potential applications of elastomers at economic cost., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The present research project is planned to prepare novel biodegradable and biocompatible hydroxyethylcellulose-g-poly(lactic acid) (HEC-g-PLA) blended polyurethanes. Hydroxyl terminated polybutadiene (HTPB) was reacted with isophorone diisocyanate (IPDI) to produce NCO-terminated polyurethane prepolymer and extended further by varying the mole ratio of chain extenders (HEC-g-PLA and BDO). The synthesized polyurethane samples were characterized by using Fourier Transform Infrared (FTIR), proton solid-state NMR ( 1 H SS NMR) and X-ray diffraction (XRD). Thermal behavior of synthesized samples was checked by using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Biological behavior of the synthesized PU samples was also tested by various biological activities which showed much dependence on the mole ratio of chain extenders. Results indicated that incorporation of grafted HEC in to the polyurethane backbone leads to improvement in antibacterial activity, anti-biofilm inhibition, biocompatibility and non-mutagenicity., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The main aim of this research work was to incorporate modified hydroxyethylcellulose (HEC) into PDMS based polyurethanes. In the first part, modification of hydroxyethylcellulose was carried out by polymerizing lactic acid (LA) with HEC using ammonia water to prepare poly(lactic acid) grafted hydroxyethylcellulose (HEC-g-PLA). The maximum degree of grafting (59.5%) was achieved at: 1:9 mole ratio of HEC/LA, 2 h, 80 °C (for activation) and 4 h, 90 °C (for reaction) with 0.74 degree of substitution. In the second part, hydroxyl terminated polybutadiene (HTPB) was reacted with isophorone diisocyanate to produce NCO-terminated polyurethane prepolymer which in turn extended by chain extender to synthesize polydimethyl siloxane hydroxyl terminated (PDMS) based polyurethanes. Effect of incorporation of HEC-g-PLA as a chain extender was studied by varying its mole ratio in PDMS based PUs. Characterization of HEC-g-PLA and all PDMS/HEC-g-PLA based polyurethane samples was carried out by using Fourier Transform Infrared (FTIR) and proton solid-state NMR ( 1 H SS NMR). Biological behavior of synthesized samples was also tested by various biological activities and results indicated that incorporation of HEC-g-PLA in to PDMS based polyurethanes leads to improvement in antibacterial activity, anti-biofilm inhibition, biocompatibility and non-mutagenicity. Therefore, HEC-g-PLA/PDMS blended polyurethanes are promising biomaterials that have potential for various biomedical applications., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In this work, chitin-curcumin based polyurethane elastomers (PUEs) were prepared by step growth polymerization technique using hydroxy terminated polybutadiene (HTPB), hexamethylene diisocyanate (HDI), chitin and curcumin. The molecular characterization was done by using FTIR and SS 1 HNMR techniques. The surface morphology and thermal stability was studied by scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA), respectively. Degree of absorption and swelling characters were also determined in water as well as in DMSO. The crystalline behavior of prepared elastomers was checked by using X-ray diffraction (XRD) and differential scanning calorimeter (DSC). Results presented that crystallinity of elastomers increased by increasing the content of chitin due to formation of more ordered structure., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Our current research work comprised of synthesis of a series of novel chitosan based water dispersible polyurethanes. The synthesis was carried out in three steps, in first step, the NCO end capped PU-prepolymer was formed through the reaction between Polyethylene glycol (PEG) (Mn = 600), Dimethylolpropionic acid (DMPA) and Isophorone diisocyanate (IPDI). In second step, the neutralization step was carried out by using Triethylamine (TEA) which resulted the formation of neutralized NCO terminated PU-prepolymer, after that the last step chain extension was performed by the addition of chitosan and followed the formation of dispersion by adding calculated amount of water. The proposed structure of CS-WDPUs was confirmed by using FTIR technique. The antimicrobial activities of the plain weave poly-cotton printed and dyed textile swatches after application of CS-WDPUs were also evaluated. The results showed that the chitosan incorporation in to PU backbone has markedly enhanced the antibacterial activity of WDPUs. These synthesized CS-WDPUs are eco-friendly antimicrobial finishes (using natural bioactive agents such as chitosan) with potential applications on polyester/cotton textiles., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The present study describes a novel ecofriendly series of chitin/curcumin/1,4-butane diol (BDO) blend derived polyurethanes (PUs), using hydroxy terminated polybutadiene (HTPB) and hexamethylene diisocyanate (HDI) along with different mole ratio of chitin, curcumin and BDO. The structural and morphological elucidation of the prepared films was done by FTIR and SEM techniques. The swelling behavior of the films was analyzed in both water and DMSO, which showed that incorporation of chitin increases the hydrophobicity and decreases the rate of swelling. Thermal analysis of synthesized PU blends revealed better thermal stability with following mole ratio 1:0.5:0.5 of chitin: curcumin: BDO as determined by TGA and DSC techniques., (Copyright © 2017 Elsevier B.V. All rights reserved.)

A series of aqueous dispersions of polyurethane (PU) and low molecular weight chitosan (CS (LMW) ) has been prepared in two steps synthetic process. In first step PU prepolymer, with NCO termini were prepared by reacting isophrone diisocyanate (IPDI), poly (caprolactone) diol (CAPA, Mn 1000), and 2,2-dimethylol propionic acid (DMPA), followed by neutralization of PU prepolymer with triethylamine (TEA). In second step PU prepolymer chain was extended by low molecular weight chitosan followed by dispersion formation by adding calculated volume of water. Molecular characterization of CS (LMW) -PU finishes was done by FTIR and application on poly-cotton blended fabric samples was confirmed by scanning electron microscopy (SEM). Antimicrobial and UV protective performance of treated fabrics was performed by AATCC 100 and AATCC TM183 methods respectively. Furthermore, it shows that the addition of chitosan remarkably increases antimicrobial and UV protective properties of PUs., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A series of polyurethane dispersions were synthesized through two step polymerization technique. A PU prepolymer with NCO termini was prepared using isophorone diisocyanate (IPDI), poly caprolactone diols (CAPA of mol. wt. 1000) and DMPA (3:1:1), and PU prepolymer chain was extended with different mole ratios of low molecular weight chitosan and finally aqueous emulsion was prepared by adding suitable volume of water. The proposed structure of chitosan based PU dispersions was confirmed through FTIR spectroscopy. The prepared aqueous CS (LMW) -CPUIs emulsions were applied onto the different quality plain weave poly-cotton dyed and printed fabric pieces using pad-dry-cure procedures. The physical properties such as air permeability, stiffness and crease recovery angle (CRA), pilling resistance, tear and tensile strength of the treated and untreated fabric samples were also evaluated. The results revealed that the incorporation of chitosan has pronounced effect on the properties of treated fabrics. This research could be extended in future for performance evaluation of pure cotton and woolen fabrics., (Copyright © 2016 Elsevier B.V. All rights reserved.)

In this work, new hexamethylene diisocyanate (HMDI) and hyroxylterminated polybutadiene (HTPB) based polyurethanes (PUs) were prepared following step growth polymerization by the introduction of varying mole ratio of chitosan (CH) and curcumin (CUR). Structural study of blends through infrared spectroscopy confirmed the incorporation of CH and CUR into the backbone of the PU. The scanning electron microscopic (SEM) study confirmed the well dispersion of incorporated chitosan/curcumin and homogeneity of surface of synthesized samples. Thermogravimetric analysis (TGA) of PU blends indicated a better thermal stability with 0.25M:0.75M of chitosan to curcumin. Mechanical properties such as modulus and tensile strength of PU blends were found to be better with higher contents of chitosan and curcumin. The same extender composition (1mol BDO, 075mol chitosan and 0.25mol curcumin) based PU showed higher substantial of antimicrobial activity as compared to the all other PUs. On the whole, this work is actually a step towards the generation of novel biocompatible materials preferably useful for biomedical applications., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Polysaccharides derived from plants are one of the largest groups of natural compounds that offer potentially beneficial functions and properties. Glucomannan, a bioactive polymer belonged to mannan family of polysaccharides is fairly abundant in nature along with superior gelling and film forming properties. Glucomannan and its derivative with several synthetic polymers are used in a biomedical and food sector especially. Polyurethanes (PUs), a commercially useful class of polymers are extensively used in both industry and everyday life because they retain exceptional properties of both plastics and elastomers. This review addresses the properties and applications of glucomannan based materials with the aim to be explored this less attempted polymer further. Furthermore this paper also presents an overview of current status and perspectives of glucomannan based polyurethane materials., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Chitin and chitosan are amino polysaccharides having massive structural propensities to produce bioactive materials with innovative properties, functions and diverse applications particularly in biomedical field. The specific physico-chemical, mechanical, biological and degradation properties offer efficient way to blend these biopolymers with synthetic ones. Polyurethane (PU) gained substantial attention owing to its structure-properties relationship. The immense activities of chitin/chitosan are successfully utilized to enhance the bioactive properties of polyurethanes. This review shed a light on chitin and chitosan based PU materials with their potential applications especially focusing the bio-medical field. All the technical scientific issues have been addressed highlighting the recent advancement in the biomedical field., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Polyurethanes (PUs) are considered currently as one of the established bio compatible and blood compatible biomaterials offering tremendous structure-property relationship. But few limitations such as low resistance to micro-emboli and thrombi are still associated with these biomaterials that restricted their applications and hence need to be modified. Heparin, a highly sulfonated and negatively charged member of glycosaminoglycan family is well established for their anti-thrombin, anticoagulant and many biological activities that make it a highly attractive candidate capable of modifying or tailoring polymer properties. Incorporation of heparin for the improvement of biocompatibility of PUs is an interesting approach and enabling emerging technology. This review focuses on the methods used for modification of PUs via heparin with their pros and cons. The major PU-heparin systems with the recent developments and their possible biomedical applications are discussed., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Recent advancements in material science and technology made it obvious that use of renewable feed stock is the need of hour. Polymer industry steadily moved to get rid of its dependence on non-renewable resources. Starch, the second largest occurring biomass (renewable) on this planet provides a cheap and eco-friendly way to form huge variety of materials on blending with other biodegradable polymers. Specific structural versatility design for individual application and tailor-made properties have established the polyurethane (PU) as an important and popular class of synthetic biodegradable polymers. Blending of starch with polyurethane is relatively a developing area in PU chemistry but with lot of attraction for researchers. Herein, various starch based polyurethane materials including blends, grafts, copolymers, composites and nano-composites, as well as the prospects and latest developments are discussed. Additionally, an overview of starch based polymeric materials, including their potential applications are presented., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Collagen is mostly found in fibrous tissues such as tendons, ligaments and skin. Collagen makes up approximately 30% of the proteins within the body. These are tough and strong structures found all over the body: in bones, tendons and ligaments. Collagen being the most abundant protein provides tensile strength via cell matrix interactions to tissue architecture. Biomimetic materials of collagen origin gained wide spread acceptance in clinical applications. Vitamin C deficiency causes scurvy a serious and painful disease in which defective collagen prevents the formation of strong connective tissue, gums deteriorate and bleed, with loss of teeth; skin discolors, and wounds do not heal. Effective collagens prevent the manifestation of such disorders. Polyurethanes on the other hand are frequently used for various applications as they offered in wide-ranging of compositions, properties and complex structures. Collagen/PU bio-composites have potential array for biomedical applications. Considering versatile properties of the elongated fibrils and wide industrial and biomedical applications including biocompatibility of polyurethane, this review shed a light on collagen based polyurethane materials with their potential applications especially focusing the bio-medical field., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The trend of using biopolymers in combination with synthetic polymers was increasing rapidly from last two or three decades. Polysaccharide based biopolymers especially starch, cellulose, chitin, chitosan, alginate, etc. found extensive applications for different industrial uses, as they are biocompatible, biodegradable, bio-renewable resources and chiefly environment friendly. Segment block copolymer character of polyurethanes that endows them a broad range of versatility in terms of tailoring their properties was employed in conjunction with various natural polymers resulted in modified biomaterials. Alginate is biodegradable, biocompatible, bioactive, less toxic and low cost anionic polysaccharide, as a part of structural component of bacteria and brown algae (sea weed) is quite abundant in nature. It is used in combination with polyurethanes to form elastomers, nano-composites, hydrogels, etc. that especially revolutionized the food and biomedical industries. The review summarized the development in alginate based polyurethanes with their potential applications., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The present research work was performed to synthesize a new series of chitosan based polyurethane elastomers (PUEs) using poly(ɛ-caprolactone) (PCL). The chitosan based PUEs were prepared by step-growth polymerization technique using poly(ɛ-caprolactone) (PCL) and 2,4-toluene diisocyanate (TDI). In the second step the PU prepolymer was extended with different mole ratios of chitosan and 1,4-butane diol (BDO). Molecular engineering was carried out during the synthesis. The conventional spectroscopic characterization of the synthesized samples using FT-IR confirms the existence of the proposed chitosan based PUEs structure. Internal morphology of the prepared PUEs was studied using SEM analysis. The SEM images confirmed the incorporation of chitosan molecules into the PU backbone., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Hydroxy terminated polybutadiene (HTPB)-chitin based polyurethanes (PUs) with controlled hydrophobicity were synthesized using HTPB and toluene diisocyanate (TDI). The prepolymer was extended with different mass ratios of chitin and 1,4-butane diol (BDO). The effect of chitin contents in chain extender (CE) proportions on surface properties was studied and investigated. Incorporation of chitin contents into the final PU showed decrease in contact angle value of water drop, water absorption (%) and swelling behavior. The antibacterial activity of the prepared samples was affected by varying the chitin contents in the chemical composition of the final PU. The results demonstrated that the use of prepared material can be suggested as non-absorbable suture., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Chitin based polyurethanes (PUs) using hydroxyl terminated polybutadiene (HTPB) as soft segment were prepared and the structure of the proposed PU was confirmed using FTIR spectrometer. PU prepolymer was prepared using HTPB and toluene-2,4-diisocyanate (TDI), and the chain was extended with different proportions of 1,4-butane diol (BDO) and chitin. During the detailed FTIR study, it was observed that tri-functional character of chitin results in the formation of network structure due to crosslinking of the material, whereas bi-functional aliphatic diol based polyurethane produced linear PU. Hydrogen bonding between the hard segments was identified by the IR spectroscopy. The scanning electron microscope (SEM) analysis also confirmed the cross-linked structure., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Chitin-hydroxyl terminated polybutadiene (HTPB) based polyurethane (PU) was prepared and structure of the pre-designed PU was confirmed using FT-IR spectrometer. The FT-IR analysis confirmed that the crosslinking density increased with increasing the chitin contents in the final PU. During the detailed FT-IR study, it was observed that tri-functional character of chitin is responsible for the formation of network structure. The scanning electron microscope (SEM) analysis also confirmed the cross-linked structure of the material. The amount of carbon, nitrogen and oxygen elements obtained from EDX-SEM microanalysis also supported the results. The resistance in solubility against the solvent also confirmed the crosslinking behavior of the prepared polyurethane., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Polyurethane acrylate copolymers (PACs) were synthesized by three step synthesis process via emulsion polymerization using toluene-2,4-diisocyanate, hydroxy terminated poly (caprolactone) diol (PCL), 2-hydroxyethylacrylate (HEA) and butyl acrylate (BuA). The proposed structure of the synthesized polyurethane acrylate copolymer (PAC) was confirmed using Fourier transform infrared (FTIR) spectrophotometer. The pilling characteristic and antimicrobial activities of the plain weave poly-cotton grey, white, printed and dyed fabric swatches after application of PAC were evaluated. The results revealed that by increasing the molecular weight of PCL in the synthesized PAC samples, the antimicrobial activities increased and this behavior was interpreted in term of increasing hydrophilic character. An increase in pilling ratings of the treated samples has been observed by increasing the molecular weight of the polycaprolactone diols in the synthesized PAC samples., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Chitin based polyurethane bio-nanocomposites (PUBNC) were prepared using chitin, Delite HPS bentonite nanoclay enriched in montmorillonite (MMT), 4,4'-diphenylmethane diisocyanate (MDI) and polycaprolactone polyol CAPA 231 (3000 g/mol(-1)). The prepolymers having different concentration of Delite HPS bentonite nanoclay were extended with 2 moles of chitin. The structures of the resulted polymers were determined by FT-IR technique. The effect of nanoclay contents on mechanical properties and in vitro biocompatibility was investigated. The mechanical properties of the synthesized materials were improved with increase in the Delite HPS bentonite nanoclay contents. Optimum mechanical properties were obtained from the PU bio-nanocomposite samples having 4% Delite HPS bentonite nanoclay. The results revealed that the final PU bio-nanocomposite having 2% Delite HPS bentonite nanoclay contents is ideal contenders for surgical threads with on going investigations into their in vitro biocompatibility, non-toxicity, and mechanical properties., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Chitin based polyurethane bio-nanocomposites (PUBNC) were prepared by emulsion polymerization. A mixture of polymer and bentonite clay enriched in montmorillonite (MMT) was formed in emulsion polymerization, in which MMT dispersed differently depending on interaction of MMT with polymer chains. Cation exchange capacity (CEC) of bentonite clay enriched in montmorillonite was found 74meq/100g. The existence of the intercalated clay by PU in the hybrid was confirmed using optical microscope (OM) technique. Optical microscope (OM) photographs verified the well dispersed ordered intercalated assembles layers of bentonite in PU matrix., (Copyright 2010 Elsevier B.V. All rights reserved.)

Shape memory polyurethanes (SMPUs) were prepared from polycaprolactone diol 4000 (PCL 4000), 1,4-butanediol (BDO), chitin, dimethylol propionic acid (DMPA), triethylamine (TEA) and 4,4'-diphenylmethane diisocyanate (MDI), and the structures of the synthesized materials were verified by infrared spectroscopy. The effects of chitin and DMPA contents in the polyurethane formulation on surface properties were investigated. DMPA provides function of making hydrophilic polyurethanes. The crystalline structure of chitin enhanced the hydrophobicity of the synthesized materials. Contact angle, water absorption, surface free energy, work of water adhesion and swelling behavior of the synthesized polyurethanes were affected by varying the DMPA and chitin contents. The interactions of the PU films with solvents on the surface were clearly related to the contents of DMPA and chitin in the final polyurethane formulation.

Biodegradable polyurethane elastomers with tunable hydrophobicity were synthesized by step-growth polymerization techniques using poly(epsilon-caprolactone) (PCL) and 4,4'-diphenylmethane diisocyanate (MDI). The prepolymer was extended with different mass ratios of chitin and 1,4-butane diol (BDO). The effect of chitin contents in chain extenders (CE) proportion on surface properties was studied and investigated. Incorporation of chitin contents into the final PU showed decrease in surface free energy and its polar component. Simultaneously, the work of water adhesion to polymer decreases significantly by increasing the chitin contents in the synthesized polymer. Contact angle measurement, water absorption and swelling behavior of the synthesized polyurethane samples were affected by varying the chitin contents in the chemical composition of the final PU. The interactions of the final PU films with solvents on the surface were displayed clear dependent on the contents of chitin in to the final polyurethane formulation. The results of different tests demonstrated that the synthesized products are a potential candidate as non-absorbable suture as previously investigated into their in vitro biocompatibility and non-toxicity [K.M. Zia, M. Zuber, I.A. Bhatti, M. Barikani, M.A. Sheikh, Int. J. Biol. Macromol. 44 (2009) 18-22].

Chitin-based polyurethane elastomers having potential for biomedical applications with tunable mechanical properties were synthesized by step growth polymerization techniques using poly(epsilon-caprolactone) (PCL) with different diisocyanates. The prepolymer was extended using chitin and/or 1,4-butane diol (BDO). The structures of the resulted polymers were determined by Fourier transform infrared (FTIR), 1H NMR and 13C NMR spectroscopic techniques. The effect of structure of diisocyanates and chain extenders on mechanical properties and in vitro biocompatibility were investigated. The results revealed that the final polymers extended with chitin are preferred candidates for surgical threads with on going investigations into their in vitro biocompatibility and non-toxicity.

Chitin based polyurethane elastomers with potential as biomedical implants with tunable mechanical properties were synthesized by step growth polymerization techniques using poly(epsilon-caprolactone) (PCL) and 4,4'-diphenylmethane diisocyanate (MDI). The prepolymer was extended with different mass ratios of chitin and 1,4-butane diol (BDO). Molecular characterization was done using FTIR, 1H NMR and 13C NMR techniques. The mechanical properties of these polymers were improved with increase in the chitin contents. Optimum mechanical properties were obtained from elastomers extended with chitin in comparison to elastomers extended with BDO. Cytotoxicity of the synthesized polyurethane samples was affected by varying the chitin contents in the chemical composition of the final polyurethane (PU). It is revealed that the final polymers extended with chitin are preferred candidates for surgical threads with on going investigations into their in vitro biocompatibility and non-toxicity.

Chitin-based polyurethane elastomers (PUEs) were synthesized by step growth polymerization techniques using poly(epsilon-caprolactone) (PCL) varying diisocyanate and chain extender structures. The viscosity average molecular weight (M(v)) of chitin was deduced from the intrinsic viscosity and found; M(v)=6.067 x 10(5). The conventional spectroscopic characterization of the samples with FTIR, (1)H NMR and (13)C NMR were in accordance with proposed PUEs structure. The crystalline behavior of the synthesized polymers were investigated by X-ray diffraction (XRD), differential scanning calorimetery (DSC) and loss tangent curves (tan delta peaks). The observed patterns of the crystalline peaks for the lower angle for chitin in the 2theta range were indexed as 9.39 degrees, 19.72 degrees, 20.73 degrees, 23.41 degrees and 26.39 degrees. Results showed that crystallinity of the synthesized PUEs samples was affected by varying the structure of the diisocyanate and chain extender. Crystallinity decreased from aliphatic to aromatic characters of the diisocyanates used in the final PU. The presence of chitin also favors the formation of more ordered structure, as higher peak intensities was obtained from the PU extended with chitin than 1,4-butane diol (BDO). The value of peak enthalpy (DeltaH) of chitin was found to be 47.13 J g(-1). The higher DeltaH value of 46.35 J g(-1) was found in the samples extended with chitin than BDO (39.73 J g(-1)).

In this work, a biologically active curcumin molecule is used as an antibacterial agent, and the insertion of this naturally occurring biomolecule into the backbone of water-dispersible polyurethane has been successfully achieved to synthesize bio-based antibacterial textile finishes. These curcumin-based water-dispersible polyurethane (CUR-WDPU) dispersions were prepared by utilizing isophorone diisocyanate (IPDI), polyethylene glycol (PEG), dimethylolpropionic acid (DMPA) and triethylamine (TEA) following the prepolymer mixing process by incorporating variable molar quantities of curcumin (CUR). Structure elucidation of synthesized CUR-WDPU dispersions was obtained through Fourier transformed infrared spectroscopy (FTIR) which confirmed the insertion of CUR into the WDPU backbone. Using the pad-dry-cure procedure, the varying varieties of plain weave polyester/cotton blended dyed and printed textile samples were treated with synthesized CUR-WDPU finishes. The antibacterial activities of these treated textiles have been assessed, and the outcomes revealed that the insertion of curcumin into the PU polymer chain has significantly boosted the antibacterial activities of PU dispersions. These newly prepared CUR-WDPUs dispersions are proved to be eco-friendly antimicrobial finishes because these are containing natural bioactive agents such as curcumin, showing potential antibacterial applications on polyester/cotton textiles. Predominantly, this research work is an attempt toward the greener approach of novel bio-based finishing materials preferably useful for textile diligences. Future investigations of these finishes will explore the other textile assets of poly-cotton textiles without adversely influencing their color fastness and mechanical properties. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A series of chitosan-based waterborne polyurethane (CS-WPU) emulsions were synthesized. • The chain extension step was done by using different mole ratios of chitosan. • The CS-WPU emulsion was applied on plain weave poly-cotton dyed and printed fabrics by using pad-dry-cure techniques. • Incorporation of chitosan affects the tear strength and antimicrobial activity of poly-cotton dyed and printed fabrics. Abstract Chitosan has gained an increased interest of researchers due to its nontoxic, biodegradable, biocompatible and renewable properties as well as its antimicrobial activity. In this work, a series of chitosan-based waterborne polyurethane (CS-WPU) emulsions were synthesized. The synthesis was accomplished by using a two-step emulsion polymerization process. The pre-polymer was prepared using hexamethylene diisocyanate (HDI) and polyethylene glycol (PEG; MW = 6 kDa). Afterwards, the chain extension step was performed by using different mole ratios of chitosan. Moreover, the effect of chitosan on physicochemical properties of the emulsion was studied. To evaluate textile performances such as tear strength, tensile strength and pilling, the CS-WPU emulsion was applied on different plain weave polyester cotton dyed and printed fabrics by using pad-dry cure techniques. The antimicrobial activity of the treated and untreated fabrics was also evaluated via the agar diffusion method. The results displayed that incorporation of chitosan has prominent effects on tensile tear strength, tear strength and antimicrobial activity of polyester cotton dyed and printed fabrics. Moreover, antimicrobial activity was considerably enhanced as the mole ratio of the chitosan was increased. The results emphasize that CS-WPU based on HDI exhibits a better performance as compared to IPDI. [ABSTRACT FROM AUTHOR]

The present research work was performed to study the properties of siloxane-based polyurethane (SPU) elastomers using aliphatic diisocyanate. SPU samples constituting of hexamethylene diisocyanate, hydroxyl-terminated polybutadiene, and polydimethylsiloxane (PDMS) were synthesized by two-step polymerization technique. Molecular engineering and surface characterization were carried out, and the outcome of the results was discussed. The conventional spectroscopic characterization of the synthesized samples using Fourier transform infrared spectroscopy confirms the existence of the proposed SPU structure. Surface properties of the synthesized material were studied determining the percentage of water absorption and equilibrium of the degree of swelling. It was found that by increasing the mole ratio of PDMS, the synthesized PU samples showed hydrophobic behavior while placing them in water and in dimethylsulfoxide solvent. [ABSTRACT FROM AUTHOR]

Abstract: The surface of the cellulosic fabrics was modified using self-prepared emulsions of polyurethane acrylate copolymers (PUACs). PUACs were prepared by varying the molecular weight of polycaprolactone diol (PCL). The PCL was reacted with isophorone diisocyanate (IPDI) and chain was extended with 2-hydroxy ethyl acrylate (HEA) to form vinyl terminated polyurethane (VTPU) preploymer. The VTPU was further co-polymerized through free radical polymerization with butyl acrylate in different proportions. The FT-IR spectra of monomers, prepolymers and copolymers assured the formation of proposed PUACs structure. The various concentrations of prepared PUACs were applied onto the different fabric samples using dip-padding techniques. The results revealed that the application of polyurethane butyl acrylate copolymer showed a pronounced effect on the tear strength and pilling resistance of the treated fabrics. [Copyright &y& Elsevier]

ABSTRACT We prepared and then blended polyurethanes (PUs) with poly(methyl methacrylate)s (PMMAs) and TiO2 by varying the percentage compositions to form pellets. The chemistry of all of the blended samples was confirmed by Fourier transform infrared spectroscopy. The incorporation of TiO2 into the PU-PMMA matrix was confirmed with scanning electron microscopy analysis. Differential scanning calorimetry analysis and compression testing was performed, and the results are discussed. The cytotoxicity level of the prepared blends displayed dependence on the composition ratio of the PU-PMMA blends. The results reveal that the optimum PU contents in the PU-PMMA-TiO2 blend were responsible for its better biocompatibility. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39806. [ABSTRACT FROM AUTHOR]

A requirement for optimum performance in a pressure-sensitive adhesive (PSA) is the right balance between viscous and elastic properties, achieved by controlling the molecular architecture. Here, waterborne polyurethane PSAs are synthesized using a blend of polyether and polyalkene-based polyols. The effects of the polyol type and molecular weight on the adhesive and thermomechanical properties are explored to optimize them for PSA applications. A linear polyurethane is synthesized by the reaction of an aliphatic diisocyanate with a diol blend of polypropylene glycol (PPG) and hydroxyl-terminated polybutadiene (HTPB). With increasing concentrations of flexible HTPB segments and the associated increased viscous dissipation a favorable increase in the tack adhesion energy and peel strength is obtained. Adhesive properties are improved with increasing PPG molecular weight because chain entanglements become possible in the soft segments and raise the storage modulus. [ABSTRACT FROM AUTHOR]

Abstract: Polyurethane acrylate copolymers (PAC) were synthesized via emulsion polymerization following three step synthesis process using toluene-2,4-diisocyanate, hydroxy terminated poly(caprolactone) diol, 2-hydroxyethylacrylate (HEA) and butyl acrylate (BuA). Structural characteristics of the synthesized polyurethane acrylate copolymer (PAC) were studied using Fourier Transform Infrared (FT-IR) spectrophotometer and are with accordance with the proposed PAC structure. The physicochemical properties such as solid contents (%), tackiness, film appearance and emulsion stability were studied, discussed and co-related with other findings. The plain weave poly-cotton printed fabrics after application of PAC was evaluated applying colorfastness standard test method. The results revealed that emulsion stability is the main controlling factor of the synthesized material in order to get better applications and properties. The emulsion stability of the synthesized material increased with increase in molecular weight of the polycaprolactone diol. [Copyright &y& Elsevier]

Abstract: Chitin based polyurethane bio-nanocomposites (PUBNC) were prepared by emulsion polymerization. The existence of the intercalated clay by polyurethane (PU) in the hybrid was confirmed using X-ray diffraction (XRD), dynamic mechanical measurements and optical microscope (OM) techniques. The values of enthalpies changes (ΔH) associated with different bentonite nanoclay contents are much consistent with the crystalline pattern of the synthesized PUBNC samples. These results revealed that pure silicate disappear in PU/bentonite nanoclay hybrid and a set of new peaks appears corresponding to the basal spacing of PU/bentonite clay bio-nanocomposites. The values of tan δ versus temperature recorded using dynamic mechanical measurements were also in accord with crystalline pattern of the PUBNC samples. [Copyright &y& Elsevier]

Abstract: Shape memory polyurethanes (SMPUs) were prepared from polycaprolactone diol 4000 (PCL 4000), 4,4′-diphenylmethane diisocyanate (MDI), 1,4-butanediol (BDO), chitin, dimethylol propionic acid (DMPA), and triethylamine (TEA). The synthesized samples were irradiated for 50, 100, and 200h in an UV exposure unit. The effects of chitin and DMPA contents in the polyurethane (PU) formulation on surface properties of the UV-irradiated PU samples were investigated by contact angle measurements, surface free energy and water absorption (%), total work of water adhesion to polymer and equilibrium degree of swelling. Results of the aforementioned surface techniques revealed that the UV-irradiated PU samples were affected by varying the UV exposure period. The interactions of the PU films with solvents on the surface were clearly related to the contents of DMPA and chitin in the final polyurethane formulation and UV-irradiation time. [Copyright &y& Elsevier]

The article discusses a study which examined the structural characteristics of ultraviolet (UV)-irradiated polyurethane (PU) elastomers extended with a series of chain extenders (CEs) having 2-10 methylene units in their structures. The study used Fourier transform infrared (FTIR) spectroscopy to investigate the chemistry of monomers and final PU samples. A continuous decrease of the bands upon long-term UV irradiation was observed in comparison with non irradiated samples.

The article discusses a study on the synthesis and thermomechanical characterization of polyurethane (PU) elastomers prepared by the reaction of poly(e-caprolactone) and 4,40-diphenylmethane diisocyanate, which was extended with a series of chain extenders (CE). Fourier transform infrared, hydrogen-nuclear magnetic resonance (H-NMR), and carbon-nuclear magnetic resonance (C-NMR) spectroscopy were used in studying the chemical structures of the synthesized PU samples.

Bio-based polyurethane (PU) coatings have been used extensively from last few decades and replaced petrochemical based coating due to their lower environmental impact, easy availability, low cost and biodegradability. Bio-derived material, such as vegetable oils, cashew nut shell liquid (CNSL), terpene, Eucalyptus tar and other bio-renewable sources, constitute a rich source of precursors for the synthesis of polyols and isocynates which are being considered for the production of “greener” PU coatings. Various chemical modifications of bio-based precursors, synthesis of various PU coatings from these modified materials and their potential applications are discussed in this review. The review examines the technological and future challenges discussed in bringing these materials to a wide range of applications, together with potential solutions, as well as discusses the major industry players who are bringing these materials to the market. This paper will focus on the progress and future opportunities of bio-based materials for coatings. [ABSTRACT FROM AUTHOR]

Abstract: Biodegradable polyurethane elastomers with potential for biomedical application as non-absorbable sutures with improved hydrophobic properties were synthesized by the reaction of poly(ε-caprolactone) (PCL) and 4,4′-diphenylmethane diisocyanate (MDI), extended with different mass ratio of chitin and 1,4-butane diol (BDO). Their molecular engineering and structural transition due to the changes of hydrogen bonding was confirmed by using FT-IR, 1H NMR and 13C NMR. Involvement of chitin was evidenced by the appearance of new signals in both 1H NMR and 13C NMR spectra, and very strong peak at 1724cm−1 in FT-IR spectra. From the results, it was concluded that the reaction of the urethane group occurred mainly at C6of chitin in which strong intermolecular and intersheet hydrogen bonds are involved. Contact angle and surface tension measurement of the synthesized polyurethane as a function of chitin contents were investigated. Optimum hydrophobicity was obtained from elastomer extended with chitin in comparison to elastomers extended with BDO. The surface free energy was also affected by chemical composition of the final PU. Structure–property relationship for prepared elastomers showed that the main determining factors were hydrogen bonding, hydrophobicity and content of chitin in polyurethane backbone. [Copyright &y& Elsevier]

Abstract: Polyurethane (PU) prepolymers were prepared by using two different diisocyanates i.e., toluene-2,4-diisocyanate (TDI) and or isophorone diisocyanate (IPDI), and poly (2-methyl-1,3-propylene glutarate), hydroxyl terminated group. PU prepolymer was reacted with 2-hydroxyethylacrylate (HEA) to form vinyl terminated PU prepolymer. Vinyl terminated PU prepolymers were further copolymerized with butyl acrylates (BuA) by emulsion process. The structure of proposed PUACs samples was confirmed by FT-IR, and their physicochemical properties were studied determining solid contents (%), emulsion stability and its appearance, tackiness and film appearance. Their acids and base chemical resistance was also studied and discussed. The synthesized PUACs samples were applied using dip-padding techniques on mill un-desized poly-cotton plain weave fabrics. The results emphasis that PUACs based on toluene-2,4-diisocyanate (TDI) have shown excellent performance against physical and chemical resistance as compared to isophorone diisocyanate (IPDI) based PUACs, however vice versa results were found in some studies. [Copyright &y& Elsevier]