Renewable Polyols for Polyurethane Synthesis via Thiol-ene/yne Couplings of Plant Oils

Hydrogels: An overview of its classifications, properties, and applications

The review paper starts with the introduction to hydrogels along with broad literature survey covering different modes of synthesis including high energy radiation methods. After that, paper covered broad classification of the hydrogels depending upon the basis of their source of origin, method of synthesis, type of cross-linking present and ionic charges on bound groups. Another advanced category response triggered hydrogels, which includes pH, temperature, electro, and light and substrate responsive hydrogels was also studied. Presented paper summarises chemical structure, properties, and synthesis of different kinds of hydrogels. Main focus was given to the preparation super absorbents such as: Semi-interpenetrating networks (semi-IPNs), Interpenetrating networks (IPNs) and cross-linked binary graft copolymers (BGCPs). The weak mechanical properties and easy degradation limit the uses of bio-based -hydrogels in biomedical field. Their properties can be improved through different chemical and physical methods. These methods were also discussed in the current research paper. Also, it includes development of hydrogels as controlled drug delivery devices, as implants and biomaterials to replace malfunctioned body parts along with their use in several other applications listed in the literature. Literature survey on the application of hydrogels in different fields like biomedical, nano-biotechnology, tissue engineering, drug delivery and agriculture was also carried out.

Thiol-Ene Coupling of High Oleic Sunflower Oil towards Application in the Modification of Flexible Polyurethane Foams

High oleic sunflower oil-based polyol was obtained by thiol-ene coupling and applied in the preparation of flexible polyurethane foams. The photochemically initiated thiol-ene click reaction was carried out under UV irradiation using 2-mercaptoethanol. Bio-based polyol with hydroxyl value of 201.4 mg KOH/g was used as 30 wt% substituent of petrochemical polyether polyol in the formulations of flexible foams. Both reference foams, as well as foams modified with bio-based polyol, were formulated to have various isocyanate indices (0.85, 0.95, 1.05). Flexible foams were compared in terms of their thermomechanical properties and analyzed using FT-IR and SEM microscopy. Modification with bio-based polyol resulted in foams with superior compression properties, higher support factor, and lower resilience than reference foams. TGA and FT-IR curves confirmed the presence of urethane/urea and ether linkages in the polyurethane matrix. Moreover, double glass transition temperature corresponding to soft and hard segments of polyurethane was observed by DSC proving the phase-separated morphology.

Thermally Reversible Polymeric Networks from Vegetable Oils

Low cross-link density thermally reversible networks were successfully synthesized from jatropha and sunflower oils. The oils were epoxidized and subsequently reacted with furfurylamine to attach furan groups onto the triglycerides, preferably at the epoxide sites rather than at the ester ones. Under the same reaction conditions, the modified jatropha oil retained the triglyceride structure more efficiently than its sunflower-based counterpart, i.e., the ester aminolysis reaction was less relevant for the jatropha oil. These furan-modified oils were then reacted with mixtures of aliphatic and aromatic bismaleimides, viz. 1,12-bismaleimido dodecane and 1,1'-(methylenedi-4,1-phenylene)bismaleimide, resulting in a series of polymers with T_g ranging between 3.6 and 19.8 °C. Changes in the chemical structure and mechanical properties during recurrent thermal cycles suggested that the Diels-Alder and retro-Diels-Alder reactions occurred. However, the reversibility was reduced over the thermal cycles due to several possible causes. There are indications that the maleimide groups were homopolymerized and the Diels-Alder adducts were aromatized, leading to irreversibly cross-linked polymers. Two of the polymers were successfully applied as adhesives without modifications. This result demonstrates one of the potential applications of these polymers.

Bio-Based Polymers with Antimicrobial Properties towards Sustainable Development

This article concisely reviews the most recent contributions to the development of sustainable bio-based polymers with antimicrobial properties. This is because some of the main problems that humanity faces, nowadays and in the future, are climate change and bacterial multi-resistance. Therefore, scientists are trying to provide solutions to these problems. In an attempt to organize these antimicrobial sustainable materials, we have classified them into the main families; i.e., polysaccharides, proteins/polypeptides, polyesters, and polyurethanes. The review then summarizes the most recent antimicrobial aspects of these sustainable materials with antimicrobial performance considering their main potential applications in the biomedical field and in the food industry. Furthermore, their use in other fields, such as water purification and coating technology, is also described. Finally, some concluding remarks will point out the promise of this theme.

One-pot approach to synthesize hyperbranched poly(thiol–ether amine) (hPtEA) through sequential “thiol–ene” and “epoxy–amine” click reactions

We demonstrated a one-pot approach to synthesize hyperbranched poly(thiol–ether amine) (hPtEA) through sequential “thiol–ene” and “epoxy–amine” click reactions, both of which were well traced using in situ¹H-NMR spectra.

Antimicrobial polyurethane thermosets based on undecylenic acid: synthesis and evaluation

In the present study, plant oil-derived surface-modifiable polyurethane thermosets are presented. Polyol synthesis is carried out taking advantage of thiol-yne photopolymerization of undecylenic acid derivatives containing methyl ester or hydroxyl moieties. The prepared methyl ester-containing polyurethanes allow surface modification treatment to enhance their hydrophilicity and impart antimicrobial activity through the following two steps: i) grafting poly(propylene glycol) monoamine (Jeffamine M-600) via aminolysis and ii) Jeffamine M-600 layer complexation with iodine. The antimicrobial activity of the iodine-containing polyurethanes is demonstrated by its capacity to inhibit the growth of Staphylococcus aureus, and Candida albicans in agar media.

Vegetable-oil-based polymers as future polymeric biomaterials

Vegetable oils are one of the most important classes of bio-resources for producing polymeric materials. The main components of vegetable oils are triglycerides - esters of glycerol with three fatty acids. Several highly reactive sites including double bonds, allylic positions and the ester groups are present in triglycerides from which a great variety of polymers with different structures and functionalities can be prepared. Vegetable-oil-based polyurethane, polyester, polyether and polyolefin are the four most important classes of polymers, many of which have excellent biocompatibilities and unique properties including shape memory. In view of these characteristics, vegetable-oil-based polymers play an important role in biomaterials and have attracted increasing attention from the polymer community. Here we comprehensively review recent developments in the preparation of vegetable-oil-based polyurethane, polyester, polyether and polyolefin, all of which have potential applications as biomaterials.