Hyperbranched Copolymers Research Articles

Preparation of super toughened flame-retardant polylactic acid with an in situ hyperbranched structure by reactive blending with a phosphorus-containing copolyester and hexamethylene glycidyl cyclotriphosphazene

Achieving both super toughness and flame retardancy in polylactic acid (PLA) materials hinges on resolving the interface compatibility issues between flame retardants, toughening agents, and PLA, as well as overcoming potential antagonisms between these components. Here, we present an approach employing hyperbranched structures to simultaneously enhance the toughness and flame retardancy of PLA materials. Our strategy involved the reactive blending of PLA with a quaternary bio-based phosphorus-containing copolyester (PPE) featuring side hydroxyl groups and hexamethylene glycidyl cyclotriphosphazene (HGCP). The multi-epoxy groups of HGCP reacted with the hydroxyl and carboxyl groups present in PPE and PLA, resulting in the formation of hyperbranched PLA-PPE copolymers. The hyperbranched copolymers provided great interfacial compatibilization and low viscosity, synergistically promoting the melt-dripping flame-retardant mechanism facilitated by PPE, aiding in the rapid removal of heat and combustible material from the pyrolysis zone. Consequently, the PLA/PPE/HGCP blends exhibited super toughness, achieving a maximum notched impact strength of 70.2 kJ/m2. Additionally, the blends demonstrated a 27 % LOI and can pass the UL-94 V-0 rating. Moreover, all the blends are biodegradable in a Proteinase K solution. This research underscores the efficacy of utilizing hyperbranched structures as a promising strategy for the development of PLA materials with simultaneous enhancement of processability, toughness, and flame retardancy.

Ultrafine Network-Like Monolayer Structures of Amphiphilic Hyperbranched Copolymers Revealed by the Relative Aggregation Number Method.

The aggregation behavior of two amphiphilic hyperbranched copolymers of poly[oligo(ethylene glycol) methacrylate-co-lauryl methacrylate] (H-[P(OEGMA-co-LMA)]) at the air/water interface was investigated by using the Langmuir film balance technique and atomic force microscopy (AFM). At the air/water interface, H-[P(OEGMA-co-LMA)] copolymers spontaneously form the ultrafine network-like monolayer structures of micelles; each micelle consists of a tiny hydrophobic core of one or two carbon backbones and lauryl side groups and a short hydrophilic shell of oligo(ethylene glycol) (OEG) side groups, and the micellar cores are connected by the branching agent ethylene glycol dimethacrylate (EGDMA). These ultrafine micellar structures are successfully revealed by our relative aggregation number method presented in this work, which is based on our previous relative mass method and methylene number method. The surface pressure-molecular area isotherms of POEGMA29%-PLMA71% (weight percent) and POEGMA69%-PLMA31% are condensed and expanded, respectively, because the density/number of OEG side groups in the former shells is smaller than that in the latter case. Upon monolayer compression, the isotherms of the former are classified into regions I-IV, whereas those of the latter are classified into regions II and III based on their different variation trends of surface pressure. Subphase pH has little influence on the isotherms of the two copolymers because the stretching degrees of hydrophilic OEG side groups in the shells are probably limited by the connected cores, which is different from the large effects in our previous block copolymers containing POEGMA or poly[oligo(ethylene glycol) acrylate] blocks. Under neutral and alkaline conditions, in region III, the mean molecular area (mmA) values of the isotherms of the two copolymers at 20 °C are smaller than those at 10 °C due to the collapse of the OEG side groups above 15 °C. Furthermore, the isotherms of POEGMA69%-PLMA31% move to larger mmA values at 30 °C due to the increased thermal mobility and stretching degrees of more OEG side groups.

RAFT copolymerization of methyl methacrylate and di(ethylene glycol) methyl ether methacrylate in a hexylpyridinium ionic liquid

AbstractSmart polymers undergo significant physical or chemical changes in response to stimuli like temperature and pH. Achieving a narrow molecular weight distribution is crucial for their sensitivity. Reversible addition–fragmentation chain transfer (RAFT) in ionic liquids is an effective method for synthesizing such polymers due to its favorable kinetics and environmental benefits. Most studies use imidazolium ionic liquids, while pyridinium ionic liquids are less common despite their easy synthesis. This study reports the first successful RAFT copolymerization of di(ethylene glycol) methyl ether methacrylate (DEGMEMA) and methyl methacrylate in N‐hexylpyridinium hexafluorophosphate ([HPY][PF6]). Both linear and hyperbranched copolymers (Mn > 25,000) with narrow molecular weight distribution were synthesized, showing observable temperature responses and biocompatibility. The linear copolymers had a desirable dispersity (Ð) of less than 1.10, while the hyperbranched copolymer had a Ð of 2.034. The lower critical solution temperatures (LCSTs) of the copolymers were close to or below the LCST of PDEGMEMA (26°C). This study indicates that pyridinium ionic liquids can be explored as a suitable solvent for synthesizing methacrylate‐based smart polymers.

Dense Monolayer Network Structures of Double Hydrophilic Hyperbranched Copolymers at the Air/Water Interface.

Influences of subphase pH and temperature on the interfacial aggregation behavior of two double hydrophilic hyperbranched copolymers of poly[oligo(ethylene glycol) methacrylate-co-(2-diisopropylamino)ethyl methacrylate] (P(OEGMA-co-DIPAEMA)) at the air/water interface are studied by the Langmuir film balance technique. Morphologies of their Langmuir-Blodgett (LB) films are characterized by atomic force microscopy (AFM). At the interface, P(OEGMA-co-DIPAEMA) copolymers tend to form a dense network structure of circular micelles composed of branching agent-connected carbon backbone cores and mixed shells of OEGMA and DIPAEMA segments (pendant groups). This network structure containing many honeycomb-like holes with diameters of 6-8nm is identified for the first time and clearly observed in the enlarged AFM images of their LB films. Under acidic conditions, surface pressure versus molecular area isotherms of the two copolymers in the low-pressure region show larger mean molecular area than those under neutral and alkaline conditions due to the lack of impediment from DIPAEMA segments. Upon further compression, each isotherm exhibits a wide pseudo-plateau, which corresponds to OEGMA segments being pressed into the subphase. Furthermore, the isotherms under neutral and alkaline conditions exhibit the lower critical solution temperature behavior of OEGMA segments, and the critical temperature is lower when the hyperbranched copolymer contains higher OEGMA content.

Novel Multi-Responsive Hyperbranched Polyelectrolyte Polyplexes as Potential Gene Delivery Vectors.

In this work, we investigate the complexation behavior of poly(oligo(ethylene glycol)methyl methacrylate)-co-poly(2-(diisopropylamino)ethyl methacrylate), P(OEGMA-co-DIPAEMA), hyperbranched polyelectrolyte copolymers, synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization, with short-linear DNA molecules. The synthesized hyperbranched copolymers (HBC), having a different chemical composition, are prepared in order to study their ability to bind with a linear nucleic acid at various N/P ratios (amine over phosphate groups). Specifically, the three pH and thermo-responsive P(OEGMA-co-DIPAEMA) hyperbranched copolymers were able to form polyplexes with DNA, with dimensions in the nanoscale. Using several physicochemical methods, such as dynamic and electrophoretic light scattering (DLS, ELS), as well as fluorescence spectroscopy (FS), the complexation process and the properties of formed polyplexes were explored in response to physical and chemical stimuli such as temperature, pH, and ionic strength. The mass and the size of polyplexes are shown to be affected by the hydrophobicity of the copolymer utilized each time, as well as the N/P ratio. Additionally, the stability of polyplexes in the presence of serum proteins is found to be excellent. Finally, the multi-responsive hyperbranched copolymers were evaluated regarding their cytotoxicity via in vitro experiments on HEK 293 non-cancerous cell lines and found to be sufficiently non-toxic. Based on our results, these polyplexes could be useful candidates for gene delivery and related biomedical applications.

Fabrication of pH and thermal dual-responsive hyperbranched copolymer grafted magnetic graphene oxide via surface-initiated RAFT-SCVP for controlled release of DOX

Herein, a novel stimuli-responsive magnetic graphene oxide/hyperbranched copolymer nanocomposites (GO@Fe3O4 @HBC) was prepared via mixing surface-initiated RAFT and self-condensing vinyl polymerization technique. In the first step, chain transfer monomer (CTM) was synthesized by the esterification reaction between 2-(dodecylthiocarbonothioylthio)− 2-methylpropionic acid (DDMAT) and 2-Hydroxyethyl methacrylate (HEMA). Besides, graphene oxide nanosheets were decorated with Fe3O4 nanoparticles. The surface of magnetic graphene oxide nanosheets was modified with 3-amino propyl (trimethoxysilyl) (APTS) and then the DDMAT was anchored to the surface of their nanosheets via amidification reaction. At last, smart hyperbranched poly (NIPAM-co-AA) was effectively grafted to the surface of magnetic graphene oxide using the SI-RAFT-SCVP technique. The chemical and physical structure of the synthesized GO@Fe3O4 @HBC were investigated by FT-IR, H NMR, GPC, TGA, DLS, CHN, VSM, UV-Vis, SEM, EDAX, and TEM. The synthesized GO@Fe3O4 @HBC was used as a nanocarrier. The drug delivery efficacy of this nanocarrier was investigated in terms of in vitro doxorubicin (DOX) release and MTT assay against HeLa cells, which confirms both acidic pH and thermo-sensitive behavior. The MTT assay also revealed that the nanocarrier without DOX was biocompatible having cell viability greater than 90% for HeLa cells. DOX-loaded nanocarrier showed high cytotoxic effect on HeLa Cells.

Hyperbranched Polyelectrolyte Copolymers as Novel Candidate Delivery Systems for Bio-Relevant Compounds.

In this study, reversible addition-fragmentation chain transfer (RAFT) polymerization is utilized in order to synthesize novel hyperbranched poly(oligoethylene glycol) methyl ether methacrylate-co-tert-butyl methacrylate-co-methacrylic acid) (H-[P(OEGMA-co-tBMA-co-MAA)]) copolymers in combination with selective hydrolysis reactions. The copolymers showing amphiphilicity induced by the polar OEGMA and hydrophobic tBMA monomeric units, and polyelectrolyte character due to MAA units, combined with unique macromolecular architecture were characterized by physicochemical techniques, such as size exclusion chromatography (SEC) and 1H-NMR spectroscopy. The hyperbranched copolymers were investigated in terms of their ability to self-assemble into nanostructures when dissolved in aqueous media. Dynamic light scattering and fluorescence spectroscopy revealed multimolecular aggregates of nanoscale dimensions with low critical aggregation concentration, the size and mass of which depend on copolymer composition and solution conditions, whereas zeta potential measurements indicated pH sensitive features. In addition, aiming to evaluate their potential use as nanocarriers, the copolymers were studied in terms of their drug encapsulation and protein complexation ability utilizing curcumin and lysozyme, as a model hydrophobic drug and a model cationic protein, respectively.

Multistep sequence-controlled supramolecular polymerization by the combination of multiple self-assembly motifs

The precise sequence control of polymer chain is an important research topic of polymer chemistry. Although some methods such as iterative synthesis and supramolecular polymerization have been developed to fabricate sequence-controllable polymer, it is still a great challenge to consecutively prepare multiple supramolecular polymers with different sequence structures. In this work, through the reasonable utilization of assembly motifs, we integrated multiple host-guest recognitions and metal coordination interactions to prepare different sequence-controlled supramolecular polymers by a multistep assembly strategy. This research provides inspiration for the design and preparation of supramolecular polymers with different sequence structures.

Application of singlet oxygen-activatable nanocarriers to boost X-ray-induced photodynamic therapy and cascaded ferroptosis for breast cancer treatment.

Ferroptosis has appealing antitumor potential that is mainly based on the accumulation of lipid peroxide to a lethal level. The cytotoxic singlet oxygen (1O2) generated from nanoscale X-ray-induced photodynamic therapy (X-PDT) may facilitate glutathione (GSH) depletion and further activate ferroptosis. To realize combined X-PDT and ferroptosis, a nanocarrier (D-NPVR) was engineered with a hyperbranched copolymer with 1O2-sensitive linkers, where both the photosensitizer (verteporfin) and ferroptosis inducer RAS-selective lethal small molecule 3 (RSL3) were encapsulated. Upon X-ray radiation, D-NPVR could produce a large amount of 1O2 for apoptosis. Subsequently, 1O2 triggered D-NP dissociation by cleavage of 1,2-bis(2-hydroxyethylthio)ethylene bonds to boost payload release and decrease levels of intracellular GSH via thiol oxidation. Liberated RSL3 is a covalent inhibitor for glutathione peroxide 4 (GPX4), which is responsible for detoxifying lipid peroxides to lipid alcohols with GSH assistance, and both 1O2-induced GSH depletion and GPX4 inactivation thereby produced ferroptotic cell death. Tumor growth inhibition in murine 4T1 tumor-bearing mice demonstrated that D-NPVR produced pronounced therapeutic efficiency where ferroptosis induction was supported by the GPX4 content and expression. This study highlights the contribution of 1O2-sensitive nanocarriers for promoting the potency of combined X-PDT and ferroptosis.

Thermo- and pH-responsive poly[(diethylene glycol methyl ether methacrylate)-co-(2-diisopropylamino ethyl methacrylate)] hyperbranched copolymers: self-assembly and drug-loading

P(DEGMA-co-DIPAEMA) hyperbranched copolymers self-assemble into large polymeric aggregates in aqueous media, when the amino groups of DIPAEMA segments are fully protonated at extreme temperatures (25 °C and 55 °C).

Synthesis and self-assembly of hyperbranched multiarm copolymer peptide conjugates based on light-induced metal-free ATRP

Light-induced metal-free ATRP was applied in the preparation of the hyperbranched multiarm copolymer peptide conjugates, which can self-assemble into monolayer or bilayer vesicles depending on the degree of branching of the hyperbranched copolymer.

Reverse osmosis membranes functionalized with polyglycidol decorated hyperbranched copolymer exhibits superior filtration performance and improved fouling resistance

In this work, we report the surface modification of commercial reverse osmosis membranes with polyglycidol functionalized cross-linked hyperbranched Polyethyleneimine-polydopamine. The polymer was synthesized in a one-pot, two-step synthesis methodology and then dip-coated onto the membranes. The coated and uncoated membranes were characterized for relevant surface characteristics i.e., surface wettability, morphology, and chemistry. Contact angle measurements showed a significant reduction in CA (from ∼ 90–20°), implying a transformation from hydrophobic to the hydrophilic character. The major functional groups of the polymer were identified on the modified membrane surface by Fourier Transform Infra-Red (FTIR) spectroscopy. Film deposition decreased the membrane surface roughness as confirmed by Scanning Electron (FESEM) & Atomic Force Microscopy (AFM) images with the copolymer depositing in the valleys of the polyamide layer. Surface modification of the membrane with the polymer not only reduced the adhesion but also interfered with the biological activity of a gram-positive species bacteria, B. subtilis, under static conditions. The uncoated membrane had large bacterial colonies as well as thick continuous biomass; in contrast, the coated ones had a sporadic presence of individual cells and very small patches of biofilm. Filtration experiments with DI water, a synthetic 35 g/L NaCl feed and actual seawater at normal RO operating pressures (∼ 55 bars), showed a significant improvement in both permeate water flux as well as salt rejection: the flux increased by 30 – 50%, whereas the rejection by 10 – 15%. Long-term biofouling and subsequent cleaning of the membranes showed the fouling on the modified membranes to be largely reversible with the flux recovery > 80%.

Hydrophobic Biodegradable Hyperbranched Copolymers with Excellent Marine Diatom Resistance.

As the utilization of degradable polymer coatings increased, the accompanying trade-off between good degradability and high-efficiency antidiatom adhesion due to their hydrophobic nature remains unresolved. The study presents a new hydrophobic surface-fragmenting coating consisting of degradable hyperbranched polymers (hereafter denoted as h-LLAx) synthesized by reversible complexation-mediated copolymerization with isobornyl acrylate (IBOA) and divinyl-functional oligomeric poly(l-lactide) (OLLA-V2), both derived from biomass, that exhibited superior resistance (∼0 cell mm-2) to marine diatom Navicula incerta (N. incerta) attachment with higher OLLA content. The combined impact of the microscale hollow semisphere micelles that self-assembled degradable hyperbranched copolymers and hydrolysis-driven self-renewable surfaces following immersion in seawater may account for the remarkable resistance of h-LLAx coatings against N. incerta. Detailed investigations were conducted across multiple perspectives, from hydrolytic degradation to broad-spectrum antibacterial attachment to ecotoxicity assessment. The excellent features of high resistance to marine diatoms and bacterial attachment, degradability, and environmental friendliness make the as-prepared h-LLAx coatings widely sought after for antifouling coating applications.

Polymerization of D,L-lactide in the presence of Boltorn™ polyester polyol

Objects. To synthesize monodisperse biodegradable hyperbranched polymers based on D,L-lactide in the presence of Boltorn™ H30 polyester polyol as a macroinitiator.Methods. 1H and 13C nuclear magnetic resonance (NMR) spectroscopy was used to study the chemical structure of the Boltorn™ H30 polyester polyol and (Boltorn™ H30)-PDLA hyperbranched copolymers. The molecular weight distribution of the polymers was studied by gel permeation chromatography (GPC). In order to study the thermal stability of Boltorn™ H30 polyester polyol, thermogravimetric analysis (TGA) was used. Polymerization of D,L-lactide was carried out in a block in the presence of Boltorn™ H30 polyester polyol.Results. The degree of branching of Boltorn™ H30 polyester polyol was calculated from NMR data, while the TGA method was used to determine the upper operational temperature range. The polymerization of D,L-lactide in the presence of Boltorn™ H30 polyester polyol used as a macroinitiator was studied. The molecular weight characteristics of the obtained copolymers were studied by NMR and GPC.Conclusions. Optimum conditions were determined for the polymerization of D,L-lactide when using Boltorn™ H30 polyester polyol as a macroinitiator. The possibility of synthesizing narrowly dispersed hyperbranched polymers (Boltorn™ H30)-PDLA under the described conditions was demonstrated.

P(OEGMA‐co‐LMA) hyperbranched amphiphilic copolymers as self‐assembled nanocarriers

AbstractWe report on the synthesis of novel amphiphilic hyperbranched copolymers, namely Hyperbranched‐[poly (ethylene glycol) methyl ether methacrylate‐co‐lauryl methacrylate] (H‐[P(OEGMA‐co‐LMA)]), obtained by reversible addition‐fragmentation chain transfer (RAFT) polymerization utilizing the divinyl monomer, ethylene glycol dimethacrylate (EGDMA) as the branching agent. Molecular characterization by size exclusion chromatography (SEC) and proton nuclear magnetic resonance (1H‐NMR) spectroscopy indicated the success of the polymerization. The self‐assembly behavior in aqueous media was investigated by light scattering techniques and fluorescence spectroscopy. The hyperbranched copolymers form multimolecular aggregates of nanoscale dimensions with a low critical aggregation concentration. In addition, the model hydrophobic drug, curcumin (CUR), known also for its intrinsic fluorescence properties, was used in order to investigate the H‐[P(OEGMA‐co‐LMA)] copolymers drug encapsulation ability. Curcumin is successfully loaded into the polymeric nanoparticles, as confirmed by dynamic light scattering and UV–Vis spectroscopy. Interestingly, curcumin hydrophobic interactions with the hyperbranched copolymers result in more well‐defined co‐assembled nanostructures, in terms of size and size distribution. The mixed copolymer‐CUR nano‐assemblies consist of small size nanoparticles (<100 nm) which exhibit relatively high size uniformity, colloidal stability and fluorescent properties. Overall, results signify that the biocompatible H‐[P(OEGMA‐co‐LMA)] nanostructures could potentially serve as nanocarrier systems for drug delivery and bio‐imaging applications.

Amphiphilic P(OEGMA-co-DIPAEMA) Hyperbranched Copolymer/Magnetic Nanoparticle Hybrid Nanostructures by Co-Assembly

This work presents the utilization of amphiphilic poly(oligo(ethylene glycol) methyl methacrylate)-co-poly(2-(diisopropylamino)ethyl methacrylate), P(OEGMA-co-DIPAEMA), hyperbranched (HB) copolymers, forming polymeric aggregates in aqueous media, as building nanocomponents and nanocarriers for the entrapment of magnetic cobalt ferrite nanoparticles (CoFe2O4, MNPs), and the hydrophobic drug curcumin (CUR) in their hydrophobic domains. Dynamic light scattering (DLS) and cryogenic transmission electron microscopy (cryo-TEM) techniques were used to evaluate the multifunctional hybrid nanostructures formed in aqueous media by co-assembly of the components and their solution properties. Magnetic nanoparticles (MNPs) or MNPs/CUR were co-assembled effectively with pre-existing polymer aggregates, leading to well-defined hybrid nanostructures. Magnetophoresis experiments revealed that the hybrid nanostructures retain the magnetic properties of MNPs after their co-assembly with the hyperbranched copolymers. The hybrid nanostructures demonstrate a significant colloidal stability under physiological conditions. Furthermore, MNPs/CUR-loaded aggregates displayed considerable fluorescence as demonstrated by fluorescence spectroscopy. These hybrid nanostructures could be promising candidates for drug delivery and bio-imaging applications.

Fabrication of Ph and Thermal Dual-Responsive Hyperbranched Copolymer Grafted Magnetic Graphene Oxide via Surface-Initiated RAFT-SCVP for Controlled Release of DOX

Fabrication of Ph and Thermal Dual-Responsive Hyperbranched Copolymer Grafted Magnetic Graphene Oxide via Surface-Initiated RAFT-SCVP for Controlled Release of DOX

Facile synthesis and self-assembly behaviors of biodegradable amphiphilic hyperbranched copolymers with reducible poly(caprolactone) grafts

A reducible hydrophobic macromonomer, HEMA-g-PCL, developed herein provides a facile yet robust strategy for biodegradable amphiphilic hyperbranched copolymers.

Elastic interface in few‐layer graphene/poly(vinylidenefluoride‐trifluoroethylene‐chlorofluoroethylene) nanocomposite with improved polarization

AbstractPolymer film capacitor exhibits extensive applications in advanced electronics because of its flexibility and huge power density. The current research interests of polymer capacitor are addressed on large energy density and high charge–discharge efficiency of composite film. Here we developed the compatible elastic interface composed of hyperbranched poly(methyl acrylate) copolymer in graphene/poly(vinylidenefluoride‐trifluoroethylene‐chlorofluoroethylene) (P(VDF‐TrFE‐CFE)) nanocomposite with high energy capability. This hyperbranched copolymer comprising polyethylene core that was grafted with poly(methyl acrylate) (PMA) segments and pyrene units was synthesized by atom transfer radical polymerization. The few‐layer graphene was exfoliated with assistance of hyperbranched copolymer that was attached on surface of flakes via π‐π non‐covalent interactions between pyrene groups and delocalized π electrons of nanosheets. Graphene/P(VDF‐TrFE‐CFE) nanocomposite film was prepared by solution casting method. The compatibility between graphene and fluoropolymer is greatly improved due to the elastic interphase of PMA segments in hyperbranched copolymer, which enhances the interfacial polarization and decreases the accumulation of charge carriers under high electric field. The energy density of 7.0 J/cm3 with charge–discharge efficiency of 60% at 300 MV/m is achieved for 0.1 wt% nanocomposite. This work reveals an effective architecture of polymer composite with elastic interface to increase the energy capability of polymer dielectric film.

Facile Synthesis of Hyperbranched Copolymers via an [A2 + B3] Click Polymerization Synthesized Reducible Hyperbranched Template

Facile Synthesis of Hyperbranched Copolymers via an [A₂ + B₃] Click Polymerization Synthesized Reducible Hyperbranched Template