Carbohydrate-Based Reprocessable and Healable Covalent Adaptable Biofoams.

Polymeric foams derived from bio-based resources and capable of self-healing and recycling ability are of great demand to fulfill various applications and address environmental concerns related to accumulation of plastic wastes. In this article, a set of polyester-based covalent adaptable biofoams (CABs) synthesized from carbohydrates and other bio-derived precursors under catalyst free conditions to offer a sustainable alternative to conventional toxic isocyanate-based polyurethane foams is reported. The dynamic β-keto carboxylate linkages present in these biofoams impart self-healing ability and recyclability to these samples.

Closed-loop recyclable and biodegradable thioester-based covalent adaptable networks.

Closed-loop recyclable and biodegradable aliphatic covalent adaptable networks (CANs) based on dynamic β-CO thioester linkages that exhibit a service temperature beyond 100 °C are reported. These CANs possessing tensile strength and modulus values of up to 0.3 and 3 MPa, respectively, effectively undergo stress relaxation above 100 °C.

Stress-Induced Shape-Shifting Materials Possessing Autonomous Self-Healing and Scratch-Resistant Ability.

Covalent adaptable networks (CANs) capable of both shape-shifting and self-healing ability offer a viable alternative to 4D printing technology to gain access to various complex shapes in a simplified manner. However, most of the reported CANs exhibit shape-shifting ability in the presence of temperature, light or chemical stimuli, which restricts their further utilization as realization of such a controlled environment is not feasible under complex scenarios. Herewith, we report a set of CANs based on a room-temperature exchangeable thia-Michael adduct, which undergoes rearrangement in network topology on application of external stress.

Healable, Recyclable, and Programmable Shape Memory Organogels Based on Highly Malleable Catalyst-Free Carboxylate Linkages.

The development of healable and recyclable organogels possessing responsive abilities is mainly hindered by the unavailability of many dynamic covalent linkages that undergo exchange reaction below the boiling temperature of organic swelling medium. Furthermore, the exchange is desired to be effective under catalyst-free conditions to circumvent the issue of catalyst leaching during the swelling process. Especially, imparting swift reversibility to thermostable carboxylate linkages is challenging.

Effect of NaCl concentration on stability of a polymer-Ag nanocomposite based Pickering emulsion: validation rheological analysis with varying temperature.

The utility of a Pickering emulsion (PEm) under saline conditions is strongly dependent on the stability of the emulsion in the presence of different salt concentrations. In this study, we have evaluated the effect of NaCl and temperature on the stability of a polyacryloyl hydrazide (PAHz)-Ag nanocomposite (NC) based PEm utilizing ocular observation, an optical microscope with a thermal stage, TGA, DLS, electrical conductivity, and rheological studies at different temperatures. The creaming stability of PEm in the presence of salt concentrations in the range of 0.

Dye-Labeled Polyacryloyl Hydrazide-Ag Nanoparticle Fluorescent Probe for Ultrasensitive and Selective Detection of Au Ion.

The efficiency of a fluorescence sensing device based on metal-enhanced fluorescence (MEF) is dependent on the optimization of interaction between the fluorophore and the metal nanoparticle (NP). Herewith, ultrasensitive and selective turn-on sensing of Au is achieved by using a suitable combination of fluorophore and metal NP system through sequential MEF effect. Dansyl hydrazide-tagged Ag NPs in the polyacryloyl hydrazide cavity are utilized to sense the picomolar concentration of Au in aqueous media.

Stable & re-dispersible polyacryloyl hydrazide-Ag nanocomposite Pickering emulsions.

Freeze drying and re-dispersibility of oil-in-water (o/w) emulsions is important from the perspective of storage, transportation and usability. A set of stable and re-dispersible o/w emulsions using polyacryloyl hydrazide (PAHz) capped Ag nanoparticles (NP) as the stabilizer is reported in which the NP size (D) and PAHz concentration collectively controlled the stability and re-dispersibility of the emulsion system. O/w emulsions prepared using different concentrations of PAHz (0.

General Reagent Free Route to pH Responsive Polyacryloyl Hydrazide Capped Metal Nanogels for Synergistic Anticancer Therapeutics.

Herewith, we report a facile synthesis of pH responsive polyacryloyl hydrazide (PAH) capped silver (Ag) or gold (Au) nanogels for anticancer therapeutic applications. A cost-effective instant synthesis of PAH-Ag or PAH-Au nanoparticles (NPs) possessing controllable particle diameter and narrow size distribution was accomplished by adding AgNO3 or AuCl to the aqueous solution of PAH under ambient conditions without using any additional reagent. PAH possessing carbonyl hydrazide pendant functionality served as both reducing and capping agent to produce and stabilize the NPs.

Polyacryloyl hydrazide based injectable & stimuli responsive hydrogels with tunable properties.

The synthesis and characterization of a series of injectable and stimuli responsive hydrogels based on polyacryloyl hydrazide have been accomplished using dimethyl 2,2'-thiodiacetate, acrylic acid (AA), diethyl malonate and polyethylene glycol diacrylate (PEGDA) as cross-linkers through a chemical or dual cross-linking pathway. The cross-linking reactions were carried out at room temperature or 70 °C to synthesize uniform and transparent gels. The swelling ratios ≈ 10-800% of the hydrogels depended on the type and concentration of the cross-linker, temperature and pH of the medium.

Polyacryloyl hydrazide: an efficient, simple, and cost effective precursor to a range of functional materials through hydrazide based click reactions.

Preparation and studies of ion exchangeable epoxy resins, stimuli responsive hydrogels, and polymer-dye conjugates have been accomplished through hydrazide based click reactions using polyacryloyl hydrazide (PAH) as the precursor. A convenient synthesis of PAH with quantitative functionality was achieved by treatment of polymethyl acrylate with hydrazine hydrate in the presence of tetra-n-butyl ammonium bromide. PAH was cured with bisphenol A diglycidyl ether (BADGE) at 60 °C to form transparent resins with superior mechanical properties (tensile strength = 2-40 MPa, Young's modulus = 3.

Surface characterization and protein interactions of segmented polyisobutylene-based thermoplastic polyurethanes.

The surface properties and biocompatibility of a class of thermoplastic polyurethanes (TPUs) with applications in blood-contacting medical devices have been studied. Thin films of commercial TPUs and novel polyisobutylene (PIB)-poly(tetramethylene oxide) (PTMO) TPUs were characterized by contact angle measurements, X-ray photoelectron spectroscopy, and atomic force microscopy (AFM) imaging. PIB-PTMO TPU surfaces have significantly higher C/N ratios and lower amounts of oxygen than the theoretical bulk composition, which is attributed to surface enrichment of PIB.

Long term in vitro biostability of segmented polyisobutylene-based thermoplastic polyurethanes.

Long term in vitro biostability of thermoplastic polyurethanes (TPUs) containing mixed polyisobutylene (PIB)/poly(tetramethylene oxide) (PTMO) soft segment was studied under accelerated conditions in 20% H(2)O(2) solution containing 0.1M CoCl(2) at 50 °C to predict resistance to metal ion oxidative degradation (MIO) in vivo. The PIB-based TPUs showed significant oxidative stability as compared to the commercial controls Pellethane 2363-55D and 2363-80A.

Peptide surface modification of P(HEMA-co-MMA)-b-PIB-b-P(HEMA-co-MMA) block copolymers.

Peptide surface modification of poly[(methyl methacrylate-co-hydroxyethyl methacrylate)-b-isobutylene-b-(methyl methacrylate-co-hydroxyethyl methacrylate)] P(MMA-co-HEMA)-b-PIB-b-P(MMA-co-HEMA) triblock copolymers with different HEMA/MMA ratios has been accomplished using an efficient synthetic procedure. The triblock copolymers were reacted with 4-fluorobenzenesulfonyl chloride (fosyl chloride) in pyridine to obtain the activated polymers [poly{(methyl methacrylate-co-fosyloxyethyl methacrylate)-b-isobutylene-b-(methyl methacrylate-co-fosyloxyethyl methacrylate)}] P(MMA-co-FEMA)-b-PIB-b-P(MMA-co-FEMA), with an activating efficiency of 80-90%. The resulting polymers were soluble in chloroform, and their solutions were used to coat thin uniform films with a predetermined thickness on smooth steel surfaces.