Showing papers in "ACS Macro Letters in 2013"
TL;DR: In this paper, a perspective is offered for the design of sustainable polymers, specifically addressing opportunities for monomer development and polymer degradation, including water degradability instead of biodegradability, incorporation of novel main chain functionality, such as acetals, utilization of lignin-based aromatics, and direct polymerization of biogenic C1 feedstocks.
Abstract: The field of sustainable polymers is growing and evolving at unprecedented rates. Researchers are increasingly concerned with the feedstock origins and the degradation behavior of, especially, large-scale commodity packaging plastics. A perspective is offered here for the design of sustainable polymers, specifically addressing opportunities for monomer development and polymer degradation. Key concepts include: water degradability instead of biodegradability; incorporation of novel main-chain functionality, such as acetals; utilization of lignin-based aromatics; and direct polymerization of biogenic C1 feedstocks.
326 citations
TL;DR: In this article, shape memory assisted self-healing (SMASH) coatings are proposed to deal with structural and functional damage to a poly(e-caprolactone) fiber.
Abstract: In this communication, we report the preparation and characterization of new shape memory assisted self-healing (SMASH) coatings. The coatings feature a phase-separated morphology with electrospun thermoplastic poly(e-caprolactone) (PCL) fibers randomly distributed in a shape memory epoxy matrix. Mechanical damage to the coating can be self-healed via heating, which simultaneously triggers two events: (1) the shape recovery of the matrix to bring the crack surfaces in spatial proximity, and (2) the melting and flow of the PCL fibers to rebond the crack. In controlled healing experiments, damaged coatings not only heal structurally, but also functionally by almost completely restoring the corrosion resistance. We envision the wide applicability of the SMASH concept in designing the next-generation self-healing materials.
320 citations
TL;DR: Structurally dynamic polydisulfide networks that inherently exhibit both shape-memory and healable properties have been synthesized as mentioned in this paper, and these materials are semicrystalline, covalently cross-linked network polymers and as such exhibit thermal shapememory properties.
Abstract: Structurally dynamic polydisulfide networks that inherently exhibit both shape-memory and healable properties have been synthesized. These materials are semicrystalline, covalently cross-linked network polymers and as such exhibit thermal shape-memory properties. Upon heating above its melting temperature (Tm) films of the material can be deformed by a force. Subsequent cooling and removal of the force result in the material being “fixed” in this strained temporary shape through a combination of crystallinity and covalent cross-links until it is exposed to temperatures above the Tm at which point it recovers to its remembered processed shape. The incorporation of disulfide bonds, which become dynamic/reversible upon exposure to light or elevated temperatures, into these networks results in them being structurally dynamic upon exposure to the appropriate stimulus. Thus, by activating this disulfide exchange, the network reorganizes, and the material can flow and exhibit healable properties. Furthermore, ex...
314 citations
TL;DR: Recent endeavors of exploiting bioorthogonal click chemistry toward the development of poly(ethylene glycol) hydrogels as cell culture scaffolds as well as biocompatible materials are emphasized.
Abstract: Over the past decade, bioorthogonal click chemistry has led the field of biomaterial science into a new era of diversity and complexity by its extremely selective, versatile, and biocompatible nature. In this viewpoint, we seek to emphasize recent endeavors of exploiting this versatile chemistry toward the development of poly(ethylene glycol) hydrogels as cell culture scaffolds. In these cell-laden materials, the orthogonality of these reactions has played an effective role in allowing the creation of diverse biochemical patterns in complex biological environments that provide new found opportunities for researchers to delineate and control cellular phenotypes more precisely than ever.
220 citations
TL;DR: In this article, the authors present the history of polymer systems that exhibit UCST behavior under mild and physiologic conditions, and present the major properties of the most recent examples of UCST in aqueous solutions.
Abstract: Polymers showing an upper critical solution temperature (UCST) in aqueous solution were not rare, but the UCST was rarely observed under practically relevant conditions. Recently, much progress has been made in the synthesis of polymer systems that display UCST behavior under mild and physiologic conditions. Current developments focus on polymers that rely on hydrogen bonding. This viewpoint explains the historical context, presents the major properties, and concludes with a discussion of the most recent examples.
179 citations
TL;DR: In this article, a telechelic poly (ethylene-co-butylene) was functionalized with hydrogen-bonding ureidopyrimidone (UPy) and cellulose nanocrystals (CNCs) decorated with the same binding motif.
Abstract: Polymers that can be repaired after being damaged are attractive, because this feature can improve the reliability, functionality, and lifetime of these materials. We report here light-healable nanocomposites based on a telechelic poly(ethylene-co-butylene) that was functionalized with hydrogen-bonding ureidopyrimidone (UPy) and cellulose nanocrystals (CNCs) decorated with the same binding motif. These nanocomposites show significantly improved mechanical properties when compared to the supramolecular polymer alone. When these materials are exposed to ultraviolet radiation, the UPy motifs are excited and the absorbed energy is converted into heat. This causes temporary disengagement of the hydrogen-bonding motifs, concomitant with a reversible decrease of the supramolecular polymers’ molecular weight and viscosity. As a result, deliberately introduced defects can be healed quickly and efficiently, even at a filler content of 20% w/w, that is, in compositions that exhibit high strength and stiffness.
174 citations
TL;DR: In this paper, the authors compared the alkaline stability of three classes of anion exchange membranes that are leading candidates for applications in platinum-free fuel cells using periodic 1H NMR sampling.
Abstract: We compared the alkaline stability of three classes of anion exchange membranes that are leading candidates for applications in platinum-free fuel cells. A methodology is presented for the study of chemical stability of anion-exchange polymers in alkaline media that provides clear and quantitative 1H NMR spectroscopic data of dissolved polymers containing benzyltrimethylammonium functionalities. Recent studies have investigated the stabilities of benzimidazolium- and alkylimidazolium-bearing polymers using periodic 1H NMR sampling. These studies included varying alkaline concentrations, external heating sources, and excessive processing and contained no internal standard for absolute measurements. Key aspects of our time-resolved 1H NMR method include in situ heating and sampling within the spectrometer, fixed stoichiometric relationships between the benzyltrimethylammonium functionalities of each polymer and potassium deuteroxide (KOD), and the incorporation of an internal standard for the absolute measu...
154 citations
TL;DR: In this article, the authors studied the stress-strain relation of dual cross-link gels having permanent cross-links and transient cross links over an unusually wide range of extension ratios and strain rates ϵ (or time t = (λ − 1)/ϵ).
Abstract: We studied the stress–strain relation of model dual cross-link gels having permanent cross-links and transient cross-links over an unusually wide range of extension ratios λ and strain rates ϵ (or time t = (λ – 1)/ϵ). We propose a new analysis method and separate the stress into strain- and time-dependent terms. The strain-dependent term is derived from rubber elasticity, while the time-dependent term is due to the failure of transient cross-links and can be represented as a time-dependent shear modulus which shows the same relaxation as in small strain. The separability is applicable except for the strain stiffening regimes resulting from the finite extensibility of polymer chains. This new analysis method should have a wide applicability not only for hydrogels but also for other highly viscoelastic soft solids such as soft adhesives or living tissues.
154 citations
TL;DR: In this paper, the authors exploit melamine (MA) to reinforce polyvinyl alcohol (PVA) via H-bond self-assembly at a molecular level, which can enhance the thermal stability of PVA to a great extent.
Abstract: Despite the high strength and stiffness of polymer nanocomposites, they usually display lower deformability and toughness relative to their matrices. Spider silk features exceptionally high stiffness and toughness via the hierarchical architecture based on hydrogen-bond (H-bond) assembly. Inspired by this intriguing phenomenon, we here exploit melamine (MA) to reinforce poly(vinyl alcohol) (PVA) via H-bond self-assembly at a molecular level. Our results have shown that due to the formation of physical cross-link network based on H-bond assembly between MA and PVA, yield strength, Young’s modulus, extensibility, and toughness of PVA are improved by 22, 25, 144, and 200% with 1.0 wt % MA, respectively. Moreover, presence of MA can enhance the thermal stability of PVA to a great extent, even exceeding some nanofillers (e.g., graphene). This work provides a facile method to improve the mechanical properties of polymers via H-bond self-assembly.
151 citations
TL;DR: Various pathways to bioconjugates based on thiol chemistry are discussed, discovered in recent years as tools to marry polymers with biomolecules such as carbohydrates, proteins, peptide, DNA, antibodies, or other building blocks from nature.
Abstract: Various pathways to bioconjugates based on thiol chemistry are discussed. Thiol-halogeno, thiol-parafluoro, thiol-ene, thiol-yne, thiol-vinylsulfone and thiol–vinyl sulfone, thiol–maleimide, thiol–bisulfone, and thiol–pyridyl disulfide are well-established synthetic routes discovered in recent years as tools to marry polymers with biomolecules such as carbohydrates, proteins, peptide, DNA, antibodies, or other building blocks from nature.
148 citations
TL;DR: In this paper, the authors compare the bound layer thickness of poly2-vinylpyridine (P2VP) and polysilicon nanoparticles (NPs) in PNCs.
Abstract: There has been considerable interest in characterizing the polymer layer that is effectively irreversibly bound to nanoparticles (NPs) because it is thought to underpin the unusual thermomechanical properties of polymer nanocomposites (PNC). We study PNCs formed by mixing silica nanoparticles (NPs) with poly-2-vinylpyridine (P2VP) and compare the bound layer thickness δ determined by three different methods. We show that the thickness obtained by thermogravimetric analysis (TGA) and assuming that the bound layer has a density corresponding to a dense melt clearly underestimates the real bound layer thickness. A more realistic extent of the bound layer is obtained by in situ measurements of the interaction pair potential between NPs in PNCs via analysis of TEM micrographs; we verify these estimates using Dynamic Light Scattering (DLS) in θ solvent. Our results confirm the existence of long-ranged interactions between NPs corresponding roughly in size to the radius of gyration of the bound chains.
TL;DR: In this paper, a conjugated porous polymer (CPP) that exhibits fluorescence quenching when exposed to TNT vapor was synthesized via a Sonaogashira cross-coupling reaction.
Abstract: A conjugated porous polymer (CPP) that exhibits fluorescence quenching when exposed to TNT vapor was synthesized via a Sonaogashira cross-coupling reaction. Two polymerization solvents, DMF and PhMe, and two activation procedures, evacuation and lyophilization, were evaluated to optimize the response of the CPP to TNT vapor. Key differences in surface area and absorption were seen as a function of polymerization solvent and activation procedure. The polymer synthesized in DMF and activated by lyophilization had the highest surface area and the strongest response to TNT vapor. This paper demonstrates the importance of growth and activation conditions in optimizing the porosity and sensing performance of CPPs.
TL;DR: A novel kind of "armed" carrier: an antibacterial polypeptide-grafted chitosan-based nanocapsule with an excellent antibacterial efficacy against both Gram-positive and Gram-negative bacteria.
Abstract: Antibacterial polypeptides as ancient immune defense systems are effective against bacteria. Here we report a novel kind of “armed” carrier: an antibacterial polypeptide-grafted chitosan-based nanocapsule with an excellent antibacterial efficacy against both Gram-positive and Gram-negative bacteria. This nanocapsule also has excellent blood compatibility and low cytotoxicity. Patients after tumor surgery may benefit from this “armed” carrier because it is highly anti-inflammation and is able to deliver anticancer and antiepileptic drugs simultaneously.
TL;DR: In this paper, a flame retardant nanocoating comprised of positively charged chitosan (CH) and anionic poly(vinyl sulfonic acid sodium salt) (PVS) was deposited onto flexible polyurethane foam using layer-by-layer assembly.
Abstract: Many current flame retardant (FR) strategies for polymers contain environmentally harmful compounds and/or negatively impact processing and mechanical properties. In an effort to overcome these issues, a effective flame retardant nanocoating comprised of positively charged chitosan (CH) and anionic poly(vinyl sulfonic acid sodium salt) (PVS) was deposited onto flexible polyurethane foam using layer-by-layer (LbL) assembly. This coating system completely stops foam melt dripping upon exposure to the direct flame from a butane torch. Furthermore, 10 CH-PVS bilayers (∼30 nm thick) add only 5.5% to the foam’s weight and completely stop flame propagating on the foam due to the fuel dilution effect from non flammable gases (e.g, water, sulfur oxides, and ammonia) released from the coating during degradation. Cone calorimetry reveals that this same coated foam has a 52% reduction in peak heat release rate relative to an uncoated control. This water-based, environmentally benign nanocoating provides an effective ...
TL;DR: A new pathway to artificial organocatalysts based on partially collapsed individual soft nano-objects displaying useful and diverse biomimetic catalytic functions is reported, showing a relatively extended morphology under good solvent conditions.
Abstract: The development of simple, efficient, and robust strategies affording the facile construction of biomimetic organocatalytic nano-objects is currently a subject of great interest. Herein, a new pathway to artificial organocatalysts based on partially collapsed individual soft nano-objects displaying useful and diverse biomimetic catalytic functions is reported. Single-chain polymer nanoparticles endowed with enzyme-mimetic activity synthesized following this new route display (i) a relatively extended morphology under good solvent conditions, as revealed by small angle neutron scattering and coarse-grained molecular dynamics simulation results, (ii) multiple, compartmentalized, and accessible catalytic sites in which borane catalytic units are retained via B···O interactions, and (iii) unprecedented reductase and polymerase enzyme-mimetic properties.
TL;DR: The present collection of state-of-the- art experimental data unambiguously demonstrates that rings exhibit a universal trend clearly departing from that of their linear counterparts, and hence it represents a major step toward resolving a 30-year old problem.
Abstract: We have measured the linear rheology of critically purified ring polyisoprenes, polystyrenes, and polyethyleneoxides of different molar masses. The ratio of the zero-shear viscosities of linear polymer melts η0,linear to their ring counterparts η0,ring at isofrictional conditions is discussed as a function of the number of entanglements Z. In the unentangled regime η0,linear/η0,ring is virtually constant, consistent with the earlier data, atomistic simulations, and the theoretical expectation η0,linear/η0,ring = 2. In the entanglement regime, the Z-dependence of ring viscosity is much weaker than that of linear polymers, in qualitative agreement with predictions from scaling theory and simulations. The power-law extracted from the available experimental data in the rather limited range 1 < Z < 20, η0,linear/η0,ring ∼ Z1.2±0.3, is weaker than the scaling prediction (η0,linear/η0,ring ∼ Z1.6±0.3) and the simulations (η0,linear/η0,ring ∼ Z2.0±0.3). Nevertheless, the present collection of state-of-the-art exp...
TL;DR: Monomethoxy poly(ethylene glycol)-b-poly(Tyr(alkynyl)-OCA, a biodegradable amphiphilic block copolymer, was synthesized by means of ring-opening polymerization and used to prepare core cross-linked polyester micelles via click chemistry.
Abstract: Monomethoxy poly(ethylene glycol)-b-poly(Tyr(alkynyl)-OCA), a biodegradable amphiphilic block copolymer, was synthesized by means of ring-opening polymerization of 5-(4-(prop-2-yn-1-yloxy)benzyl)-1,3-dioxolane-2,4-dione (Tyr(alkynyl)-OCA) and used to prepare core cross-linked polyester micelles via click chemistry. Core cross-linking not only improved the structural stability of the micelles, but also allowed controlled release of cargo molecules in response to the reducing reagent. This new class of core cross-linked micelles can potentially be used in controlled release and drug delivery applications.
TL;DR: In this article, a 3D Troger's-base-derived microporous organic polymer with a high surface area and good thermal stability was facilely synthesized from a one-pot metal-free polymerization reaction between dimethoxymethane and triaminotriptycene.
Abstract: A 3D Troger’s-base-derived microporous organic polymer with a high surface area and good thermal stability was facilely synthesized from a one-pot metal-free polymerization reaction between dimethoxymethane and triaminotriptycene. The obtained material displays excellent CO2 uptake abilities as well as good adsorption selectivity for CO2 over N2. The CO2 storage can reach up to 4.05 mmol g–1 (17.8 wt %) and 2.57 mmol g–1 (11.3 wt %) at 273 K and 298 K, respectively. Moreover, the high selectivity of the polymer toward CO2 over N2 (50.6, 298 K) makes it a promising material for potential application in CO2 separation from flue gas.
TL;DR: In this article, l-proline moieties bound to a thermoresponsive polymer nanoreactor efficiently directed the asymmetric aldol reaction in water with excellent yields and enantioselectivity.
Abstract: l-Proline moieties bound to a thermoresponsive polymer nanoreactor efficiently directed the asymmetric aldol reaction in water with excellent yields and enantioselectivity (ee). The reactions were efficient at higher temperatures in direct contrast to the low yields and ee values found when the reaction was carried out in a DMF/water mixture due to the location of the l-proline moieties within the hydrophobic pocket inside the core of the nanoreactors. This ideal environment formed for catalysis allows control over the water content as well as enhancing interactions between the carboxylic acid of l-proline and the aldehyde substrate. The nanoreactors were disassembled to fully water-soluble polymers by lowering the temperature to below the lower critical solution temperature (LCST) of the polymer, resulting in precipitation of the product in near pure form. The product was isolated by centrifugation and the polymer/water solution reused in additional catalytic cycles by heating the polymer above its LCST ...
TL;DR: The shape memory behavior of a series of strong, tough hybrid hydrogels prepared by covalently cross-linking quad-polymers of N,N-dimethylacrylamide (DMA), 2-(N-ethylperfluoro-octanesulfonamido) et al. as discussed by the authors.
Abstract: The shape memory behavior of a series of strong, tough hybrid hydrogels prepared by covalently cross-linking quad-polymers of N,N-dimethylacrylamide (DMA), 2-(N-ethylperfluoro-octanesulfonamido) et...
TL;DR: In this article, the synthesis of well-defined high molecular weight block copolymers by sequential in situ chain extensions via Cu(0)-mediated living radical polymerization is reported, and the optimal conditions for iterative block formation are determined using model homopolymer quasiblock systems.
Abstract: The synthesis of well-defined high molecular weight block copolymers by sequential in situ chain extensions via Cu(0)-mediated living radical polymerization is reported. Optimal conditions for iterative high molecular weight block formation were determined using model homopolymer quasiblock systems, including methyl acrylate (MA), ethyl acrylate (EA), and n-butyl acrylate (nBA; each block DPn ≈ 100). The PDI after each chain extension was below 1.2, with good agreement between theoretical and experimental molecular weights, while the conversion of monomer incorporation into each distinct block was 95–100% (up to 6 blocks). To demonstrate this approach for true block copolymer materials, well-defined block polymers containing MA, ethylene glycol methyl ether acrylate (EGMEA), and tert-butyl acrylate (tBA) were prepared in high purity: diblock P(MA-b-EGMEA) and triblock P(MA-b-tBA-b-MA). These were prepared in high yields, on multigram scales, and with purification only required at the final step. To the be...
TL;DR: In this article, direct hetero-arylation polymerization (DHAP) was used to obtain 3,4-propylenedioxythiophene-based conjugated polymers for use in electrochromics.
Abstract: We report the use of direct (hetero)arylation polymerizations (DHAP) as a means of obtaining 3,4-propylenedioxythiophene-based conjugated polymers for use in electrochromics. This method offers a rapid route to achieving polymers in high yields with simplified purification procedures and low residual metal content, as determined by inductive coupled plasma-mass spectrometry (ICP-MS). The studied polymers possess comparable electrochromic properties to those previously reported by our group, implying that their switching ability from a colored to a transmissive state is independent of the residual metallic impurities.
TL;DR: In this article, a polymerized ionic liquid diblock copolymer with high hydroxide conductivity and nanoscale morphology was reported, which has a significant impact on low-cost (platinum-free), long-lasting, solid-state alkaline fuel cells.
Abstract: Herein, we report a polymerized ionic liquid diblock copolymer with high hydroxide conductivity and nanoscale morphology. Surprisingly, the conductivity is not only higher (over an order of magnitude) than its random copolymer analog at the same ion and water content, but also higher than its homopolymer analog, which has a higher ion and water content than the block copolymer. These results should have a significant impact on low-cost (platinum-free), long-lasting, solid-state alkaline fuel cells.
TL;DR: In this paper, an omniphobic slippery surface prepared by infusing a fluorinated lubricant into a porous polyelectrolyte multilayer is presented. But it is not suitable for nonplanar surfaces.
Abstract: Omniphobic and slippery coatings from lubricant-infused, textured surfaces have recently been shown to have superior properties including low contact angle hysteresis and low sliding angles. Here, we present an omniphobic slippery surface prepared by infusing a fluorinated lubricant into a porous polyelectrolyte multilayer. These surfaces repel water and decane with sliding angles as low as 3°. One advantage of polyelectrolyte multilayers is the ease with which they can coat nonplanar surfaces, demonstrated here.
TL;DR: In this article, a covalently crosslinked hydrogel comprising the strain-promoted reaction product of an 8-member cycloalkyne functionalized polyalkylene glycol and a multi-arm glycerol exytholate triazide was presented.
Abstract: The present invention is directed to a covalently crosslinked hydrogel comprising the strain-promoted reaction product of an 8-member cycloalkyne functionalized polyalkylene glycol and a multi-arm glycerol exytholate triazide and methods for making them. Because the precursor materials can be manipulated without causing crosslinking, provided the strain threshold is not reached, these hydrogels permit mechanical control over when (and where) cross linking occurs and are easier to use than prior strain-activated or temperature-activated systems. These novel hydrogels do not require a catalyst to cross link, thus avoiding the biocompatibility problems common to many catalysts. Nor is the crosslinking process affected by the presence of catalysts or other substances, which have interfered with crosslinking in known strain induced hydrogels. Because of their crosslinking reaction kinetics, these novel hydrogels can encapsulate and transport highly sensitive cells and other biological additives and have no known toxic byproducts.
TL;DR: In this article, the solution properties of the NIPAAm homopolymers and statistical copolymers were investigated and it was found that besides temperature and pH, the statistical copylacrylamide was also responsive to the presence of free glucose in solution.
Abstract: Statistical copolymers of N-isopropylacrylamide (NIPAAm) and 5-methacrylamido-1,2-benzoxaborole (MAAmBo) have been synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization. The solution properties of the NIPAAm homopolymers and statistical copolymers were investigated and it was found that, besides temperature and pH, the statistical copolymers were also responsive to the presence of free glucose in solution. Furthermore, responsive hydrogels and nanogels were formed spontaneously by simply mixing the statistical copolymers of P(NIPAAm-st-MAAmBO)s and well-defined glycopolymers. These gels were found to have temperature, pH, and glucose responsive properties.
TL;DR: In this article, an approach to prepare polymer composites with chiral nematic photonic structures through the self-assembly of cellulose nanocrystal (CNC) dispersions in organic solvents is described.
Abstract: We describe an approach to prepare polymer composites with chiral nematic photonic structures through the self-assembly of cellulose nanocrystal (CNC) dispersions in organic solvents. Contrary to previous reports, we demonstrate that dispersions of neutralized sulfated CNCs in polar organic media readily form lyotropic chiral nematic liquid crystalline phases. We have investigated the effect of the neutralizing base on the CNC self-assembly, observing chiral nematic ordering for all counterions studied. The self-assembly of the organic CNC dispersions can be exploited to prepare iridescent polymeric composites simply by casting the CNC dispersion with a suitable polymer soluble in the organic solvent. Photonic properties of the composite films can be easily controlled by either varying the ratio of CNCs to polymer or adding salts.
TL;DR: In this article, a cationic polyelectrolyte based on the styrenic ionic liquid tributyl-4-vinylbenzylphosphonium pentanesulfonate was found to undergo a lower critical solution temperature (LCST)-type phase transition in aqueous solutions.
Abstract: A cationic polyelectrolyte based on the styrenic ionic liquid tributyl-4-vinylbenzylphosphonium pentanesulfonate was found to undergo a lower critical solution temperature (LCST)-type phase transition in aqueous solutions. This phase transition occurs in a wide temperature range in terms of polymer concentration as well as type and concentration of externally added salts. Anion exchange and salting out effects are responsible for the flexible phase transition temperature.
TL;DR: A very efficient synthesis strategy for the construction of artificial transient-binding protein-mimic nano-objects that in solution resemble disordered multidomain proteins, whereas in the dry state adopt a collapsed, globular morphology, as observed by transmission electron microscopy.
Abstract: We report herein a very efficient synthesis strategy for the construction of artificial transient-binding protein-mimic nano-objects. Michael addition-mediated multidirectional self-assembly of individual polymeric chains at r.t. leads to “Michael” nanocarriers that in solution resemble disordered multidomain proteins, as revealed by a combination of small angle neutron scattering measurements and coarse-grained molecular dynamics simulation results, whereas in the dry state adopt a collapsed, globular morphology, as observed by transmission electron microscopy. This extended-to-compact morphology transition taking place upon solvent removal is of paramount importance, among other applications, for the construction of efficient biosensors based on immobilized protein-mimic nano-objects and for the development of transient vitamin-binding systems. As a proof of concept, we show the controlled delivery of vitamin B9 from these novel transient-binding nanocarriers.
TL;DR: A quantitative, additive-free, and one-pot reaction cascade involving the ring-opening of a thiolactone by primary amine treatment and subsequent conversion of the released thiol groups via Michael addition to an acrylate has been utilized for the double modification/functionalization of poly(N-isopropyl acrylamide), yielding tailor-made thermoresponsive polymers.
Abstract: A quantitative, additive-free, and one-pot reaction cascade involving the ring-opening of a thiolactone by primary amine treatment and subsequent conversion of the released thiol groups via Michael addition to an acrylate has been utilized for the double modification/functionalization of poly(N-isopropyl acrylamide), yielding tailor-made thermoresponsive polymers. After proving a quantitative double functionalization, different amine/acrylate combinations were employed in order to demonstrate the general applicability of the concept. Cloud points can be tuned by adjusting the amount of ring-opening amine in the reaction mixture, which enables to control the degree of modification.