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A novel graphdiyne aerogel was successfully synthesized with excellent gas adsorption capacity.

Core cross-linked star poly(2-oxazoline)s are promising materials for drug-delivery applications.

This paper reports novel hybrid arborescent polypeptides based on poly(γ-benzyl l-glutamate)

Fluorescent drug delivery systems have received increasing attention in cancer therapy because they combine drug delivery and bioimaging into a single platform. For example, polymers with aggregation-induced emission (AIE) fluorophores, such as tetraphenylethylene (TPE), have emerged as an elegant choice for drug delivery/bioimaging applications. In this work, we report one-pot sequential organocatalytic ring-opening polymerization of e-caprolactone (CL) and ethylene oxide (EO) using TPE-(OH)2 as a difunctional initiator, in the presence of a t-BuP2/TEB Lewis pair (catalyst), in THF at room temperature. Two well-defined triblock copolymers with inverse block sequences, TPE-(PCL-b-PEO)2 and TPE-(PEO-b-PCL)2, were synthesized by altering the sequential addition of CL and EO. The physicochemical properties, including hydrodynamic diameter, morphology, and AIE properties of the synthesized amphiphilic triblock copolymers were investigated in aqueous media. The block copolymer micelles were loaded with anticancer drugs doxorubicin and curcumin to serve as drug delivery vehicles. In vitro studies revealed the accelerated drug release at lower pH (5.5), which mimics the tumor microenvironment, different from the physiological pH (7.4). In vitro cytotoxicity studies demonstrated that the neat block copolymer micelles are biocompatible, while drug-loaded micelles exhibited a significant cytotoxic effect in cancer cells. Cellular uptake, examined by confocal laser scanning microscopy, showed that the block copolymer micelles were rapidly internalized by the cells with simultaneous emission of TPE fluorophore. These results suggest that these triblock copolymers can be utilized for intracellular bioimaging.

We present the design, synthesis, and characterization of triple hydrogen-bond-forming precursors and their supramolecular triblock copolymers. Thymine end-functionalized polystyrene-b-polyisoprene...

Well-defined linear, 3-, 4-, and 6-arms polyvinylidene fluoride (PVDF) stars are synthesized by reversible addition−fragmentation chain transfer (RAFT) polymerization using mono-, tri-, tetra-, and hexa-functionalized chain transfer agents, respectively, and 1,1-bis-(tert-butylperoxy)-cyclohexane as initiator. The crystallization kinetics and the polymorphic character of PVDF stars are investigated by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) . Using a cooling rate of 10 °C min−1, all samples form α- and β-phases. However, the amount of β-phase increases with respect to the α-phase as the number of arms in the PVDF stars increases. This results from the increased topological complexity in the stars , which leads to the preferential formation of the less thermodynamically stable ferroelectricβ-phase. When the cooling rate is decreased (1 °C min−1) and/or an isothermal crystallization procedure is applied, polymorphism is inhibited in the PVDF stars, and only the paraelectric α-phase is formed. On the other hand, the linear PVDF sample is still capable of producing both paraelectric and ferroelectric phases after slow cooling or isothermal crystallization. The isothermal crystallization kinetics of the PVDF stars i faster than the linear as a result of their speedier nucleation, possibly promoted by their particular topology where the arms radiate from a common junction point., F.A., G.Z., and N.H. thankfully acknowledge the support of King Abdullah University of Science and Technology (KAUST). N.M., J.M., and A.J.M. acknowledge the support of the Basque Government through grant IT1503-22. N.M. thankfully acknowledges his Ph.D. fellowship from the POLYMAT Basque Center for Macromolecular Design and Engineering. J.M. acknowledges partial financial support from the IBERDROLA Foundation.

The great significance of boosting the design of percolating nanopore structures in block copolymers (BCPs) for varied use cases has been widely demonstrated in the past several decades. However, it still remains challenging to prepare the desired porous structures in a rapid, facile, and universal manner. Here we develop an unconventional and benchtop strategy to rapidly generate the nanoporous BCPs with arbitrary structural characters regardless of the BCP bulk morphology. This universal pore-forming strategy enables the sustainable CO2-based BCPs to form the advanced membranes with 1 s soaking for efficiently rejecting 94.2% brilliant blue R (826 g/mol). At the same time, the water permeance retains around 1020 L/(m2·h·bar), which is 1~3 orders of magnitude higher than that of other membranes. This strategy may offer a fantastic opportunity to introduce percolating pore structures in those newly developed BCPs with which the previously reported pore-forming methods may not deal.

A series of ester-ether copolymers were obtained via the reaction between α,ω-dihydroxyl poly(ϵ-caprolactone) (PCL) and ethylene oxide (EO) or monosubstituted epoxides catalyzed by strong phosphazene bases. The two types of monomeric units were distributed in highly random manners due to the concurrence of epoxide ring-opening and fast transesterification reactions. The substituent of epoxide showed an interesting bidirectional effect on the enzymatic degradability of the copolymer. Compared with PCL, copolymers derived from EO exhibited enhanced hydrophilicity and decreased crystallinity which then resulted in higher degradability. For the copolymers derived from propylene oxide and 1,2-butylene oxide, the hydrophobic alkyl pendant groups also allowed lower crystallinity of the copolymers thus higher degradation rates. However, further enlarging the pendant groups by using styrene oxide or 2-ethylhexyl glycidyl ether caused a decrease in the degradation rate, which might be ascribed to the higher bulkiness hindering the contact of ester groups with lipase.

Two novel allylic arsonium ylide monomers with a phenyl (steric and electronic effect) group at different positions were synthesized and used in boron-catalyzed polymerization to produce a series of well-defined polymers, poly(2-phenyl-propenylene

This work was supported by King Abdullah University of Science and Technology, grants REP/1/3848-01-01, URF/1/4040-01-01 and base lines.

A series of alkyl‐subsituted dienyltriphenylarsonium ylides were synthesized and used as monomers in borane‐initiated polymerization to obtain practically pure C5‐polymers (main‐chain grows by five carbon atoms at a time). The impact of triethylborane (Et3B), tributylborane (Bu3B), tri‐sec‐butylborane (s‐Bu3B), and triphenylborane (Ph3B) initiators on C5 polymerization was studied. Based on NMR and SEC results, we have shown that all synthesized polymers have C5 units with a unique unsaturated backbone where two conjugated double bonds are separated by one methylene. The synthesized C5‐polymers possess predictable molecular weights and narrow molecular weight distributions (M n,NMR=2.8 −11.9 kg mol−1, Ð=1.04–1.24). It has been found that increasing the steric hindrance of both the monomer and the initiator can facilitate the formation of more C5 repeating units, thus driving the polymerization to almost pure C5‐polymer (up to 95.8 %). The polymerization mechanism was studied by 11B NMR and confirmed by DFT calculations. The synthesized C5‐polymers are amorphous with tunable glass‐transition temperatures by adjusting the substituents of monomers, ranging from +30.1 °C to −38.4 °C. Furthermore, they possess blue photoluminescence that changes to yellow illuminating the polymers for 5 days with UV radiation of 365 nm (IIE, isomerization induced emission)., A series of new alkyl‐substituted dienyltriphenylarsonium ylides was synthesized and used as monomers in the borane‐initiated polymerization, achieving almost pure C5‐polymer (95.8 %), with photoluminescent properties.

This work is financially supported by the National Natural Science Foundation of China (21801049) and the Opening Project of Key Laboratory of Polymer Processing Engineering (South China University of Technology), Ministry of Education. N.H. acknowledges the support of the King Abdullah University of Science and Technology.

An efficient "one-pot" strategy for the structure-controlled synthesis of hyperbranched polymers (HBPs) based on a "latent" inimer (LI-Br), containing a furan-protected maleimide monomer and a haloalkane initiator, is presented. At high temperatures, the "latent" inimer is converted to a "real" inimer after releasing maleimide (MI) via a retro-Diels-Alder (r-DA) reaction and then copolymerized with methyl methacrylate by self-condensing vinyl copolymerization. Due to the dynamic characteristic of the r-DA reaction, the release of naked MI and the subsequent copolymerization can be regulated by the temperature or stereochemistry of Diels-Alder (DA) adducts. Thus, the "one-pot" structure-controlled synthesis of HBPs with various degrees of branching was achieved. By further implementation of a programmable temperature change, some valuable hyperbranched topologies such as star-shaped and long-chain hyperbranched polymers can be constructed avoiding sophisticated synthetic routes.

We investigate for the first time the morphology and crystallization of two novel tetrablock quarterpolymers of polyethylene (PE), poly(ethylene oxide) (PEO), poly(ϵ-caprolactone) (PCL), and poly(l-lactide) (PLLA) with four potentially crystallizable blocks: PE187.1-b-PEO3715.1-b-PCL2610.4-b-PLLA197.6 (Q1) and PE299.5-b-PEO268.8-b-PCL237.6-b-PLLA227.3 (Q2) (superscripts give number average molecular weights in kg/mol, and subscripts give the composition in wt %). Their synthesis was performed by a combination of polyhomologation (C1 polymerization) and ring-opening polymerization techniques using a ″catalyst-switch″ strategy, either ″organocatalyst/metal catalyst switch″ (Q1 sample, 96% isotactic tetrads) or ″organocatalyst/organocatalyst switch″ (Q2 sample, 84% isotactic tetrads). Their corresponding precursors - triblock terpolymers PE-b-PEO-b-PCL, diblock copolymers PE-b-PEO, and PE homopolymers - were also studied. Cooling and heating rates from the melt at 20 °C/min were employed for most experiments: differential scanning calorimetry (DSC), polarized light optical microscopy (PLOM), in situ small-angle X-ray scattering/wide-angle X-ray scattering (SAXS/WAXS), and atomic force microscopy (AFM). The direct comparison of the results obtained with these different techniques allows the precise identification of the crystallization sequence of the blocks upon cooling from the melt. SAXS indicated that Q1 is melt miscible, while Q2 is weakly segregated in the melt but breaks out during crystallization. According to WAXS and DSC results, the blocks follow a sequence as they crystallize: PLLA first, then PE, then PCL, and finally PEO in the case of the Q1 quarterpolymer; in Q2, the PLLA block is not able to crystallize due to its low isotacticity. Although the temperatures at which the PEO and PCL blocks and the PE and PLLA blocks crystallize overlap, the analysis of the intensity changes measured by WAXS and PLOM experiments allows identifying each of the crystallization processes. The quarterpolymer Q1 remarkably self-assembles during crystallization into tetracrystalline banded spherulites, where four types of different lamellae coexist. Nanostructural features arising upon sequential crystallization are found to have a relevant impact on the mechanical properties. Nanoindentation measurements show that storage modulus and hardness of the Q1 quarterpolymer significantly deviate from those of the stiff PE and PLLA blocks, approaching typical values of compliant PEO and PCL. Results are mainly attributed to the low crystallinity of the PE and PLLA blocks. Moreover, the Q2 copolymer exhibits inferior mechanical properties than Q1, and this can be related to the PE block within Q1 that has thinner crystal lamellae according to its much lower melting point., This work has received funding from MINECO through projects MAT2017-83014-C2-1-P and MAT2017-88382-P, from the Basque Government through grant IT1309-19, and from the ALBA synchrotron facility through granted proposal u2020084441 (March 2020). We would like to thank the financial support provided by the BIODEST project; this project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement no. 778092.

The authors thank Dr. Andrew S. Bailey, Dr. Anwar H. Khawajah, and Dr. Hongrui Ma of Saudi Aramco for the many fruitful discussions on the subject. The authors also are grateful to Saudi Aramco for the research grant and the technical support.

Brush-type macromolecules (BMs) have attracted much attention over the past decades because of their unique properties and potential applications in nanoscience, drug-delivery systems, and photonic...

The “coordination-insertion” ring-opening polymerization (ROP) mechanism has so far been the monopoly of metal catalysts. In this work, we present a metal-free “coordination-insertion” ROP of trimethylene carbonate (TMC) and ε-caprolactone (ε-CL), as well as their sequential block copolymerization, with N-trimethylsilyl-bis (trifluoromethanesulfonyl)imide (TMSNTf2) as the non-metallic initiator/catalyst. TMSNTf2 was proposed to work through an unprecedented metal-free “coordination-insertion” mechanism, which involves the coordination of monomer to the Si atom of TMSNTf2, the nucleophilic attack of the –NTf2 group on the coordinated monomer, and the cleavage of the acyl–oxygen bond of the monomer. The proposed metal-free “coordination-insertion” ROP was studied by NMR, SEC, and MALDI-TOF analyses. In addition, the TMSNTf2-mediated ROP of TMC and ε-CL led to linear and cyclic polymers following two-stage first-order polymerization processes, as evidenced by structural analyses and kinetics study, which further demonstrated the metal-free “coordination-insertion” mechanism., The first metal-free “coordination-insertion” ROP of cyclic carbonate and lactones mediated by N-trimethylsilyl-bis(trifluoromethanesulfonyl)imide (TMSNTf2) was proposed, which in the past was exclusively the monopoly of metal complex catalysts.

Poly(ester-carbonate) copolymers were synthesized through triethylborane (TEB)-activated, one-pot copolymerization of epoxides with anhydrides (AH) and CO₂. Depending upon the feeding ratio of AH to the epoxides, poly(ester-carbonate) copolymers with random and tapered ester structures could be derived due to the much higher reactivity of AH toward growing oxanions compared to the reactivity of CO₂. Anhydrides like succinic anhydride (SA) and phthalic anhydride (PA) when tried in terpolymerization with epoxides, like propylene oxide (PO) and cyclohexene oxide (CHO), and CO₂ indeed exhibited such high reactivities in comparison to CO₂ that tapered block structures were eventually obtained for high feeding ratios of AH to PO and random copolymers for the AH-to-epoxide feeding ratio lower than 10%. Terpolymerization with different feeding ratios of anhydrides to epoxides was thus systematically investigated. In an alternate path, diblock poly(ester-b-carbonate)s were prepared by sequential copolymerization of epoxide/anhydride and epoxide/CO₂. All of the obtained copolymers were characterized by ¹H nuclear magnetic resonance (NMR), diffusion-ordered spectroscopy (DOSY), gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). The structures and properties of copolymers obtained by terpolymerizations and block copolymerizations were compared.

The first C5 polymerization is reported, where the main‐chain is growing by five carbon atoms of the monomer at a time. Three dienyltriphenylarsonium ylide monomers were synthesized and polymerized with triethylborane as an initiator, leading to random terpolymers (C1, C3, C5) with mainly C5 repeating units (up to 84.1 %). It has been found that the methyl group (electron‐donating substituent) on the conjugated double bond of the ylides facilitates the formation of C5 segments. A mechanism was proposed based on NMR characterization and DFT calculations. The high C5 content ensures that things are on the right track for pure C5 homopolymerization., Reported for the first time is an unusual borane‐initiated polymerization of arsonium ylide monomers, where the main‐chain grows by five carbon atoms, from the monomer, at a time and leads to unique structures.

We report a new synthetic methodology for poly(ester amide)s by anionic ring‐opening copolymerization of N‐sulfonyl aziridines and cyclic anhydrides. Phosphazenes organocatalysts have been found to promote a highly‐active, controlled, and selective alternating copolymerization in the absence of any competitive side reaction (zwitterionic mechanism and exchange transacylations). Mechanistic studies have shown first‐order dependence of the copolymerization rate in N‐sulfonyl aziridines and phosphazenes, and zero‐order in cyclic anhydrides. This one‐pot methodology leads not only to homopolymers but also to poly(ester amide)‐based block copolymers. Two catalytic cycles involving ring‐opening alternating copolymerization of N‐sulfonyl aziridines with cyclic anhydrides and ring‐opening polymerization of N‐sulfonyl aziridines have been proposed to explain the one pot synthesis of poly(ester amide)‐based homo‐ and block copolymers., Phosphazene organocatalysts have been found to promote a highly‐active, controlled, and selective alternating ring‐opening copolymerization of N‐sulfonyl aziridines and cyclic anhydrides. This one‐pot methodology leads not only to homopolymers but also to poly(ester amide)‐based block copolymers.

A versatile strategy for smart fluorescent materials is lacking due to their diverse responding mechanisms and incompatibility of responsive behaviors. Herein an adaptable strategy is presented toward a multi-stimuli-responsive fluorescent material with stage-by-stage responsive behavior by blending linear polymers modified with different stimulus-responsive moieties and AIE cross-linker. Under stimuli, the linear polymer can cross-link with the cross-linker to form networks, which intrinsically restrict the intramolecular rotation of the AIE molecule to induce strong emission. A unified stimuli-responsive mechanism is involved in that various stimuli are transferred through the organized "stimulus-crosslink-emission" process. This strategy ensures the compatibility of different stimuli-responses and the adjustability of stimulus-response behavioral logic. These multi-stimuli-responsive fluorescent materials exhibited strong accessibility and adaptability for information encryption.

We report a series of poly(ester amide)s (PEAs) synthesized by organocatalytic ring-opening polymerization (ROP) of

A rapid and efficient method to remove thiocarbonylthio end groups from polymers prepared by reversible addition-fragmentation chain transfer (RAFT) is described. The elimination process is obtained in less than 1 min by treating the solution of RAFT-synthesized polymers with 5 equiv of trialkylborane (TAB) in the presence of oxygen under an ambient temperature. The versatility of this method was checked on the most relevant families of thiocarbonylthio chain transfer agents (CTA), including dithioesters, trithiocarbonates, dithiocarbamates, and xanthates, carried by the corresponding RAFT-synthesized polymers. UV, NMR, and MALDI-TOF MS characterization results all confirm the complete removal of their terminal CTA groups.

Whatever the chemistry used for the synthesis of aliphatic polycarbonates, in particular, those of high molar mass, the adventitious presence of water leads to bimodal GPC traces and affords polycarbonate samples of uncontrolled and unpredictable molar masses. It appears that among all reagents used in the copolymerization of CO

Two star triblock terpolymers (PS-b-P2VP-b-PEO)3 and one dendritic-like terpolymer [PS-b-P2VP-b-(PEO)2]3 of PS (polystyrene), P2VP (poly(2-vinylpyridine)), and PEO (poly(ethylene oxide)), never reported before, were synthesized by combining atom transfer radical and anionic polymerizations. The synthesis involves the transformation of the −Br groups of the previously reported Br-terminated 3-arm star diblock copolymers to one or two −OH groups, followed by anionic polymerization of ethylene oxide to afford the star or dendritic structure, respectively. The well-defined structure of the terpolymers was confirmed by static light scattering, size exclusion chromatography, and NMR spectroscopy. The self-assembly in solution and the morphology in bulk of the terpolymers, studied by dynamic light scattering and transmission electron microscopy, respectively, reveal new insights in the phase separation of these materials with complex macromolecular architecture.

The synthesis of cyclic polymers on a large scale is a challenging task for polymer scientists due to the requirement of ultra-high dilution conditions. In this paper, we demonstrate an alternative method to prepare cyclic polymers with moderate dilution and up to 1 gram scale. We employed a simple Williamson etherification reaction to prepare cyclic polymers with a good solvent/non-solvent combination. In this way, various polystyrene (PS) and polyethylene glycol (PEG) cyclic homopolymers were synthesized. Anionic polymerization using high vacuum techniques combined with the postpolymerization reaction was used to generate linear dihydroxy PS precursors. The synthesized linear and cyclic homopolymers were fully characterized using various spectroscopic and analytical techniques, such as size exclusion chromatography (SEC), matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF-MS), and differential scanning calorimetry (DSC). Detailed nuclear magnetic resonance (NMR) spectroscopic studies were also performed to obtain the complete structural information of the synthesized polymers.

The research reported in this publication was supported by the King Abdullah University of Science (KAUST) and Technology and by the Basque Government through grant IT1309-19.

The direct copolymerization of p-tosyl isocyanate (TSI) with epoxides, initiated by onium salts in the presence of trialkylborane, to produce polyurethanes is reported. The rate of copolymerization and the (regio)selectivity were investigated in relation to the trialkylborane and the initiator used. Under optimized conditions such copolymerizations have been successfully performed for a wide range of epoxides, including ethylene oxide, propylene oxide, 1-octene oxide, cyclohexene oxide, and allyl glycidyl ether. These copolymerizations afford a new category of polyurethanes, clear of side products such as cyclic oxazolidinone, isocyanurate, and poly(isocyanate) linkages. The experimental conditions used in this work are compatible with those for the organocatalytic (co)polymerization of other oxygenated monomers and CO2 , holding the potential for their terpolymerization with p-tosyl isocyanate and the development of new materials with unprecedented properties.

Functionalized polypeptides have attracted tremendous interest in recent years and found many stimulating applications owing to their tunable physicochemical characteristics including hydrophilicity and stimuli-responsive behavior. The development of new strategies to produce these polymers without metallic contaminants is crucial for their applications in high-value and sensitive domains, such as biomedical, microelectronic, food-packaging, and personal beauty care fields. Herein, a highly efficient strategy to access well-defined site-specific functionalized polypeptides is developed by combining Michael reaction with hydrogen-bonding organocatalytic ROP of NCA. A library of chain-end and chain-middle functionalized polypeptides (14 examples) with predesigned molecular weights and low polydispersities are readily prepared with this approach. Specifically, the whole synthetic process is metal-free, fulfilling high activity and selectivity at room temperature.

This work has received funding from MINECO through project MAT2017-83014-C2-1-P, from the Basque Government through grant IT1309-19, and from the ALBA synchrotron facility through granted proposal 2018093081 (March 2019).

We combine synthesis, physical experiments, and computer simulations to investigate self-assembly patterns of low-functionality telechelic star polymers (TSPs) in dilute solutions. In particular, in this work, we focus on the effect of the arm composition and length on the static and dynamic properties of TSPs, whose terminal blocks are subject to worsening solvent quality upon reducing the temperature. We find two populations, single stars and clusters, that emerge upon worsening the solvent quality of the outer block. For both types of populations, their spatial extent decreases with temperature, with the specific details (such as temperature at which the minimal size is reached) depending on the coupling between inter- and intra-molecular associations as well as their strength. The experimental results are in very good qualitative agreement with coarse-grained simulations, which offer insights into the mechanism of thermoresponsive behavior of this class of materials.

Supramolecular block copolymers (PS-DAT-sb-PI-Thy) were synthesized via noncovalent hydrogen bonding between well-defined thymine end-functionalized polyisoprene (PI-Thy) and diaminotriazine (DAT) end-functionalized polystyrene (PS-DAT). Three covalently linked block copolymers were also synthesized for comparison with the noncovalent supramolecular block copolymers. The complementary DAT/Thy interaction resulted in the microphase separation of the supramolecular block copolymer system. Detailed characterization of all functionalized homopolymers and block copolymers was carried out via proton nuclear magnetic resonance (1H NMR) spectroscopy, gel permeation chromatography, matrix-assisted laser desorption/ionization-time of flight mass spectrometry, and differential scanning calorimetry. The self-assembly process of supramolecular block copolymers was evidenced by transmission electron microscopy. Small-angle X-ray scattering was also performed to study the microphase separation of supramolecular and covalently linked block copolymers. Comparison of microphase separation images of supramolecular block copolymers and the corresponding covalently linked analogues reveals differences in d-spacing and microdomain shape.

Well-defined polyethylene (PE)-based 3-miktoarm star copolymers (PI)2PE-OH, PI2(PI′-b-PE)-OH and terpolymer PI2(PS-b-PE)-OH (PI: polyisoprene, PS: polystyrene), bearing a functional group (−OH) at ...