Carbon dioxide-based copolymers with various architectures

CO2-Sourced Polymer Dyes for Dual Information Encryption

Large amounts of small molecule dyes leak into the ecosystems annually in harmful and unsustainable ways. Polymer dyes have attracted much attention because of their high migration resistance, excellent stability, and minimized leakage. However, the complex synthesis process, high cost, and poor degradability hinder their widespread application. Herein, green and sustainable polymer dyes are prepared using natural dye quercetin (Qc) and CO2 through a one-step process. The CO2-sourced polymer dyes show strong migration resistance, high stability, and can be degraded on demand. Additionally, the CO2-sourced polymer dyes showed unique responses to Zn2+, leading to significantly enhanced fluorescence, highlighting their potential for information encryption/decryption. The CO2-sourced polymer dyes can solve the environmental hazards caused by small molecule dye leakage and promote the carbon cycle process. Meanwhile, the one-step synthesis process is expected to achieve sustainable and widespread utilization of CO2-sourced polymer dyes.

Temperature-Responsive Lactic Acid-Based Nanoparticles by RAFT-Mediated Polymerization-Induced Self-Assembly in Water

This work demonstrates for the first-time biobased, temperature-responsive diblock copolymer nanoparticles synthesized by reversible addition-fragmentation chain-transfer (RAFT) aqueous emulsion polymerization-induced self-assembly (PISA). Here, monomers derived from green solvents of the lactic acid portfolio, N,N-dimethyl lactamide acrylate (DMLA) and ethyl lactate acrylate (ELA), were used. First, DMLA was polymerized by RAFT aqueous solution polymerization to produce a hydrophilic PDMLA macromolecular chain transfer agent (macro-CTA), which was chain extended with ELA in water to form amphiphilic PDMLA-b-PELA diblock copolymer nanoparticles by RAFT aqueous emulsion polymerization. PDMLA_x homopolymers were synthesized targeting degrees of polymerization, DP_x from 25 to 400, with relatively narrow molecular weight dispersities (Đ < 1.30). The PDMLA₆₄-b-PELA_y diblock copolymers (DP_y = 10-400) achieved dispersities, Đ, between 1.18 and 1.54 with two distinct glass transition temperatures (T_g) identified by differential scanning calorimetry (DSC). T_g(1) (7.4 to 15.7 °C) representative of PELA and T_g(2) (69.1 to 79.7 °C) of PDMLA. Dynamic light scattering (DLS) studies gave particle z-average diameters between 11 and 74 nm (PDI = 0.04 to 0.20). Atomic force microscopy (AFM) showed evidence of spherical particles when dispersions were dried at ∼5 °C and film formation when dried at room temperature. Many of these polymers exhibited a reversible lower critical solution temperature (LCST) in water with a concomitant increase in z-average diameter for the PDMLA-b-PELA diblock copolymer nanoparticles.

Elucidation of the Alternating Copolymerization Mechanism of Epoxides or Aziridines with Cyclic Anhydrides in the Presence of Halide Salts

Organic halide salts in combination with metal or organic compound are the most common and essential catalysts in ring-opening copolymerizations (ROCOP). However, the role of organic halide salts was neglected. Here, we have uncovered the complex behavior of organic halides in ROCOP of epoxides or aziridine with cyclic anhydride. Coordination of the chain-ends to cations, electron-withdrawing effect, leaving ability of halide atoms, chain-end basicity/nucleophilicity, and terminal steric hindrance cause three types of side reactions: single-site transesterification, substitution, and elimination. Understanding the complex functions of organic halide salts in ROCOP led us to develop highly active and selective aminocyclopropenium chlorides as catalysts/initiators. Adjustable H-bonding interactions of aminocyclopropenium with propagating anions and epoxides create chain-end coordination process that generate highly reactive carboxylate and highly selective alkoxide chain-ends.

Well-Defined and Highly Effective Nickel Catalysts Coordinated on Tridentate SNO Schiff-Base Derivatives for Alternating Copolymerization of Epoxides and Anhydrides

A series of Ni complexes supported by SNO Schiff-base derivatives were synthesized in this study. Complex synthesis and characterization data are reported herein. Treatment of the pro-ligands [L¹-H = 2-(((2-(methylthio)ethyl)imino)methyl)phenol, L²-H = 2,4-di-tert-butyl-6-(((2-(methylthio)ethyl)imino)methyl)phenol, L³-H = 2-(((2-(methylthio)ethyl)imino)methyl)-4,6-bis(2-phenylpropan-2-yl)phenol, L⁴-H = 4-bromo-2-(((2-(methylthio)ethyl)imino)methyl)phenol, and L⁵-H = 4-chloro-2-(((2-(methylthio)ethyl)imino)methyl)phenol] with Ni(OAc)₂·4H₂O in refluxing ethanol afforded six-coordinate mono-Ni(II) complexes [L₂ⁿNi] (n = 1-5). Noteworthy, a heptanuclear nickel(II) octacarboxylate species complex 6 and dinuclear nickel complex 6a resulted from treatment of L⁶-H [4-fluoro-2-(((2-(methylthio)ethyl)imino)methyl)phenol] with different metal precursors [Ni(OAc)₂·4H₂O for 6; NiBr₂ for 6a] giving a quantitative yield. The reaction of nickel acetate tetrahydrate and L⁷-H to L⁹-H [L⁷-H = 2-methoxy-6-(((2-(methylthio)ethyl)imino)methyl)phenol, L⁸-H = 5-methoxy-2-(((2-(methylthio)ethyl)imino)methyl)phenol, and L⁹-H = 4-methoxy-2-(((2-(methylthio)ethyl)imino)methyl)phenol] produced the four-coordinate complexes [L₂ⁿNi] (n = 7-9). The highest performing catalyst was complex 3, which was highly efficient for the ring-opening copolymerization of phthalic anhydride (PA) and cyclohexene oxide (CHO) in the presence of a cocatalyst (4-dimethylaminopyridine). In addition, the same copolymerization conditions produced narrowly dispersed polyesters, with high selectivity and polymerization control. In addition to PA-CHO copolymerization, efficient diglycolic anhydride-PA and PA-propene oxide copolymerization was achieved under the same conditions. These catalysts are straightforward to produce and extend the scope of potential substrates.

Solvent-assisted self-assembly of block copolymer thin films

Solvent-assisted block copolymer self-assembly is a compelling method for processing and advancing practical applications of these materials due to the exceptional level of the control of BCP morphology and significant acceleration of ordering kinetics. Despite substantial experimental and theoretical efforts devoted to understanding of solvent-assisted BCP film ordering, the development of a universal BCP patterning protocol remains elusive; possibly due to a multitude of factors which dictate the self-assembly scenario. The aim of this review is to aggregate both seminal reports and the latest progress in solvent-assisted directed self-assembly and to provide the reader with theoretical background, including the outline of BCP ordering thermodynamics and kinetics phenomena. We also indicate significant BCP research areas and emerging high-tech applications where solvent-assisted processing might play a dominant role.

Organocatalytic selective coupling of episulfides with carbon disulfide for the synthesis of poly(trithiocarbonate)s and cyclic trithiocarbonates

Selective coupling of CS2 with episulfides affords perfectly alternating poly(trithiocarbonate)s or cyclic trithiocarbonates upon the onium salts used.

Borinane-based organoboron catalysts for alternating copolymerization of CO2 with cyclic ethers: improved productivity and facile recovery

Organoboron catalysts including an ammonium salt separated by a few carbon–carbon bonds to a boron center were designed and synthesized. Borinane-based organoboron catalysts exhibited highest activity for the copolymerization of CO2 and epoxides.

Orthogonally grown polycarbonate and polyvinyl block copolymers from mechanistically distinct (co)polymerizations

Mechanistically distinct polymerization systems can afford unique block copolymers that would not be accessible by mere sequential polymerization.

Synthesis of Diverse Polycarbonates by Organocatalytic Copolymerization of CO2 and Epoxides: From High Pressure and Temperature to Ambient Conditions

Organophosphazenes combined with triethylborane (TEB) were selected as binary organocatalyts for the copolymerization of CO₂ and epoxides. Both the activity and selectivity were highly dependent on the nature of phosphazenes. 2,4,6-Tris[tri(1-pyrrolidinyl)-iminophosphorane]-1,3,5-triazine (C₃ N₃ -Py-P₃ ) with a relatively low basicity (pK_a =26.5 in CD₃ CN) and a bulky molecular size (φ=1.3 nm) exhibited an unprecedented efficiency (TON up to 12240) and selectivity (>99 % polymer selectivity and >99 % carbonate linkages) toward copolymerization of CO₂ and cyclohexene oxide (CHO), and produced CO₂ -based polycarbonates (CO₂ -PCs) with high molar masses (M_n up to 275.5 kDa) at 1 MPa of CO₂ and 80 °C. Surprisingly, this binary catalytic system achieved efficient CO₂ /CHO copolymerization with TOF up to 95 h^-1 at 1 atm pressure and room temperature.

Mg(ii) heterodinuclear catalysts delivering carbon dioxide derived multi-block polymers

Carbon dioxide derived polymers are emerging as useful materials for applications spanning packaging, construction, house-hold goods and automotive components. To accelerate and broaden their uptake requires both more active and selective catalysts and greater structural diversity for the carbon dioxide derived polymers. Here, highly active catalysts show controllable selectivity for the enchainment of mixtures of epoxide, anhydride, carbon dioxide and lactone. Firstly, metal dependent selectivity differences are uncovered using a series of dinuclear catalysts, Mg(ii)Mg(ii), Zn(ii)Zn(ii), Mg(ii)Zn(ii), and Mg(ii)Co(ii), each exposed to mixtures of bio-derived tricyclic anhydride, cyclohexene oxide and carbon dioxide (1 bar). Depending upon the metal combinations, different block structures are possible with Zn(ii)Zn(ii) yielding poly(ester-b-carbonate); Mg(ii)Mg(ii) or Mg(ii)Co(ii) catalysts delivering poly(carbonate-b-ester); and Mg(ii)Zn(ii) furnishing a random copolymer. These results indicate that carbon dioxide insertion reactions follow the order Co(ii) > Mg(ii) > Zn(ii). Using the most active and selective catalyst, Mg(ii)Co(ii), and exploiting reversible on/off switches between carbon dioxide/nitrogen at 1 bar delivers precision triblock (ABA), pentablock (BABAB) and heptablock (ABABABA) polymers (where A = poly(cyclohexylene oxide-alt-tricyclic anhydride), PE; B = poly(cyclohexene carbonate), PCHC). The Mg(ii)Co(ii) catalyst also selectively polymerizes a mixture of anhydride, carbon dioxide, cyclohexene oxide and ε-caprolactone to deliver a CBABC pentablock copolymer (A = PE, B = PCHC C = poly(caprolactone), PCL). The catalysts combine high activity and selectivity to deliver new polymers featuring regularly placed carbon dioxide and biomass derived linkages.

Terpolymerization of CO2 with Epoxides and Cyclic Organic Anhydrides or Cyclic Esters

The synthesis of polymeric materials starting from CO2 as a feedstock is an active task of research. In particular, the copolymerization of CO2 with epoxides via ring-opening copolymerization (ROCOP) offers a simple, efficient route to synthesize aliphatic polycarbonates (APC). In many cases, APC display poor physical and chemical properties, limiting their range of application. The terpolymerization of CO2 with epoxides and organic anhydrides or cyclic esters offers the possibility, combining the ROCOP with ring-opening polymerization (ROP), to access a wide range of materials containing polycarbonate and polyester segments along the polymer chain, showing enhanced properties with respect to the simple APC. This review will cover the last advancements in the field, evidencing the crucial role of the catalytic system in determining the microstructural features of the final polymer.

Strategies for the synthesis of block copolymers with biodegradable polyester segments

Oxygenated block copolymers with biodegradable polyester segments can be prepared in one-pot through sequential or simultaneous addition of monomers. This review highlights the state of the art in this area.

Chiral salenCo(iii) complexes with bulky substituents as catalysts for stereoselective alternating copolymerization of racemic propylene oxide with carbon dioxide and succinic anhydride

Stereoregular poly(propylene carbonate)s and poly(propylene succinate-block-carbonate)s were synthesized with new chiral salenCo(iii) catalysts carrying bulky substituents.

Synthesis of functional CO2-based polycarbonates via dinuclear nickel nitrophenolate-based catalysis for degradable surfactant and drug-loaded nanoparticle applications

Functional CO₂-based polycarbonates via efficient catalysis strategies using well-defined dinickel catalysts and their biomedical applications for the synthesis of drug-loaded nanoparticles were reported.

A biodegradable CO2-based polymeric antitumor nanodrug via a one-pot surfactant- and solvent-free miniemulsion preparation

In the present study, low molecular weight poly(propylene carbonate) (PPC, Mn = 3500), a biodegradable liquid polymer easily prepared from carbon dioxide (CO2), was modified into poly(propylene carbonate)diacrylate (PPC-DA) by acylation, and methoxy poly(ethylene glycol) (mPEG) was modified into methoxy poly(ethylene glycol) acrylate (mPEG-A). Using PPC-DA as the dispersant to dissolve hydrophobic doxorubicin (DOX) and the initiator, and with mPEG-A as the co-monomer and polymerisable surfactant, a biodegradable nanodrug with excellent biocompatibility was prepared by shear emulsification polymerization without surfactants or organic solvent residues. The nanodrug can be efficiently endocytosed by tumor cells and can rapidly release doxorubicin triggered by the acidic endosomal pH. As evidenced by experiments in tumor-bearing mice, such a nanodrug is stealthy during blood circulation, and targets tumor sites with high efficiency. Moreover, this nanodrug is more effective and less toxic than free doxorubicin. This study provides a green and versatile approach for preparing biodegradable nanodrugs via a simple and efficient process. Moreover, this study extends the applications of CO2 based polymers in the biomedical field, promoting the development of CO2 polymerization fixation.

Recycling a Borate Complex for Synthesis of Polycarbonate Polyols: Towards an Environmentally Friendly and Cost-Effective Process

In this investigation, a metal-free process was developed that enables the synthesis of poly(propylene carbonate) (PPC) diols/polyols by copolymerization of CO₂ with propylene epoxide (PO) under environmentally friendly and cost-effective conditions. This process implies the recycling of triethylborane and of ammonium salts that both enter in the composition of the initiators used to copolymerize CO₂ and PO. In complement to the above approach, a polymeric support, poly(diallyl dimethylammonium chloride), was synthesized and modified to carry ammonium carboxylate salts along its chain. The prepared polymeric initiator was utilized to copolymerize CO₂ with PO under heterogeneous conditions. Not only were the polymerization results similar to the samples obtained under homogeneous conditions, but the polymer substrate could easily be recovered by simple filtration. The integrity of the polycarbonate diols/polyols and the recycling process were followed by ¹ H and ¹¹ B NMR spectroscopy, gel permeation chromatography, and matrix assisted laser desorption ionization time of flight (MALDI-TOF) MS.