Recent Advances in Structural Modifications of Hyperbranched Polymers and Their Applications

pH-Responsive Hyperbranched Polymer Scaffolds for Polymer and Peptide Conjugation through Molecular Recognition: Synthesis and Self-Assembly

Hyperbranched polymers can be suitable polymeric scaffolds for the modification of functional groups and fabrication of applicable nanoparticles considering their good solubility, numerous modification sites, and unique self-assembly behaviors. To facilitate the modification process and obtain various functional hyperbranched polymers, a new inimer 2-((adamantan-1-yl)amino)-1-(4-((2-bromo-2-methylpropanoyl)oxy)phenyl)-2-oxoethyl methacrylate (ABMA) with an adamantyl group was prepared in this research through the Passerini reaction. ABMA was copolymerized with 2-(diisopropylamino)ethyl methacrylate (DPA), affording the pH-responsive hyperbranched polymer hPDPA. Model molecules poly(ethylene glycol) (PEG) and the peptide RRRRRRRRC (PArg) with a cell-penetrating octaarginine fragment were conjugated with β-cyclodextrin (β-CD) to modify the hPDPA through molecular recognition. The inclusion complex hPDPA/PEG self-assembled into micelles in phosphate buffer at pH 7.4, while hPDPA/PEG/PArg self-assembled into vesicles because of the repulsion of the positively charged PArg. It was demonstrated that the DOX-loaded hPDPA/PEG/PArg could be internalized by Hela cells with high efficiency and could induce apoptosis of Hela cells.

A Novel Cellulose-Supported Polymer Electrolyte with High Ionic Conductivity for Lithium Metal Batteries

The traditional liquid electrolytes pose safety hazards primarily attributed to the flammability of organic solvent, whereas solid-state electrolytes can significantly enhance the safety of lithium-ion batteries. Polymer solid electrolytes are being considered as an effective solution due to their excellent flexibility and low cost, but they suffer low ionic conductivity or high interface impedance. Here, the ketone-containing allyl acetoacetate monomers were polymerized within the cellulose membrane via UV photopolymerization to prepare a cellulose-supported poly-allyl acetoacetate polymer electrolyte. The PAAA electrolyte shows the ion conductivity of 1.14 × 10-4 S cm-1 and the electrochemical stability window of 4.5 V. The Li symmetric battery can stably cycle for 1500 h at 0.1 mA cm-2. The LiFeO4‖Li cell achieves a discharge specific capacity of 160 mAh g-1 and demonstrates excellent cycling stability. Matching with Ni-rich cathodes also delivers decent performance. The designed polymer electrolyte with high ionic conductivity offers new ideas and directions for the development of future energy storage technology.

Mixed-charge hyperbranched polymer nanoparticles with selective antibacterial action for fighting antimicrobial resistance

The escalating menace of antimicrobial resistance (AMR) presents a profound global threat to life and assets. However, the incapacity of metal ions/reactive oxygen species (ROS) or the indiscriminate intrinsic interaction of cationic groups to distinguish between bacteria and mammalian cells undermines the essential selectivity required in these nanomaterials for an ideal antimicrobial agent. Hence, we devised and synthesized a range of biocompatible mixed-charge hyperbranched polymer nanoparticles (MCHPNs) incorporating cationic, anionic, and neutral alkyl groups to effectively combat multidrug-resistant bacteria and mitigate AMR. This outcome stemmed from the structural, antibacterial activity, and biocompatibility analysis of seven MCHPNs, among which MCHPN7, with a ratio of cationic groups, anionic groups, and long alkyl chains at 27:59:14, emerged as the lead candidate. Importantly, owing to inherent differences in membrane potential among diverse species, alongside its nano-size (6-15 nm) and high hydrophilicity (Kow = 0.04), MCHPN7 exhibited exceptional selective bactericidal effects over mammalian cells (selectivity index > 564) in vitro and in vivo. By inducing physical membrane disruption, MCHPN7 effectively eradicated antibiotic-resistant bacteria and significantly delayed the emergence of bacterial resistance. Utilized as a coating, MCHPN7 endowed initially inert surfaces with the ability to impede biofilm formation and mitigate infection-related immune responses in mouse models. This research heralds the advent of biocompatible polymer nanoparticles and harbors significant implications in our ongoing combat against AMR. STATEMENT OF SIGNIFICANCE: The escalating prevalence of antimicrobial resistance (AMR) has been acknowledged as one of the most significant threats to global health. Therefore, a series of mixed-charge hyperbranched polymer nanoparticles (MCHPNs) with selective antibacterial action were designed and synthesized. Owing to inherent differences in membrane potential among diverse species and high hydrophilicity (Kow = 0.04), the optimal nanoparticles exhibited exceptional selective bactericidal effects over mammalian cells (selectivity index >564) and significantly delayed the emergence of bacterial resistance. Importantly, they endowed surfaces with the ability to impede biofilm formation and mitigate infection-related immune responses. Furthermore, the above findings focus on addressing the problem of AMR in Post-Pandemic, which will for sure attract attention from both academic and industry research.

Cytocompatible Hyperbranched Polyesters Capable of Altering the Ca2+ Signaling in Neuronal Cells In Vitro

Synthetic hyperbranched polyesters with potential therapeutic properties were synthesized using the bifunctional polyethylene glycol or PEG with different molecular weights, ca., 4000, 6000, and 20,000 g/mol, and the trifunctional trans-aconitic acid or TAA. During polycondensation, a fixed amount of PEG was allowed to react with varying amounts of TAA (1:1 and 1:3) to control the branching extents. It was found that the synthetic polyesters had a considerable yield and were highly water soluble. Spectroscopic data (Fourier transform infrared and 1H NMR) confirmed the polyester formation; the branching percentages were determined from 1H NMR spectroscopy which varied from 73% to 22% among the synthesized samples. As the molecular weight of PEG was increased, the branching percentage drastically dropped. All polyesters were found to be negatively charged due to the ionization of unreacted -COOH in the branched ends at the working pH (7.4). Both the hydrodynamic size and intrinsic viscosity were found to reduce as the branching extent increased. Among the sets of polyesters, the one with the highest branching percentage (73%) showed the core-shell morphology (evident from field emission scanning electron microscopy and transmission electron microscopy studies). It also exhibited the highest efficiency toward Ca2+ influx in neuronal cells due to the unique morphology and the negatively charged surface. Nevertheless, this particular grade of polyester along with all the other grades was cytocompatible and induced reactive oxygen species generation. Since the maximally branched grade was highly efficient in altering the Ca2+ signaling through stronger influx, it may well be tested for treating neuronal disorders in vivo in future.

Self-Assembly of Hydrophobic Hyperbranched PLMA Homopolymer with -COOH End Groups as Effective Nanocarriers for Bioimaging Applications

Nanomedicine is a discipline of medicine that applies all aspects of nanotechnology strategies and concepts for treatment and screening possibilities. Synthetic polymer nanostructures are among the many nanomedicine formulations frequently studied for their potential as vectors. Bioimaging is a valuable diagnostic tool, thus, there is always a demand for new excipients/nanocarriers. In this study, hydrophobic hyperbranched poly(lauryl methacrylate) (PLMA) homopolymers comprised of highly hydrophobic LMA moieties with -COOH polar end groups were synthesized by employing reversible addition-fragmentation chain transfer (RAFT) polymerization. Ethylene glycol dimethacrylate (EGDMA) was utilized as the branching agent. End groups are incorporated through the RAFT agent utilized. The resulting amphiphilic hyperbranched polymer was molecularly characterized by size exclusion chromatography (SEC), Fourier transformation infrared spectroscopy (FT-IR), and 1H-NMR spectroscopy. Pyrene, curcumin, and IR-1048 dye were hydrophobic payload molecules successfully encapsulated to show how adaptable these homopolymer nanoparticles (prepared by nanoprecipitation in water) are as dye nanocarriers. This study demonstrates a simple way of producing excipients by generating polymeric nanoparticles from an amphiphilic, hyperbranched, hydrophobic homopolymer, with a low fraction of polar end groups, for bioimaging purposes.

Synthesis and Morphology Characteristics of New Highly Branched Polycaprolactone PCL

A simple and efficient method for the synthesis of biodegradable, highly branched polycaprolactone (PCL) is presented. The solvent-free (bulk) reaction was carried out via ring opening polymerization (ROP), catalyzed by tin octanoate Sn(Oct)2, and it employed hyperbranched polyamide (HPPA) as a macro-initiator. The core-shell structure of the obtained products (PCL-HPPA), with the hyperbranched HPPA core and linear PCL chains as shell, was in the focus of the product characterization. 1H nuclear magnetic resonance (1H NMR) and elemental analysis confirmed the covalent incorporation of the HPPA in the products, as well as a high degree of grafting conversion of its amino functional groups. Confocal Raman Micro spectroscopy, and especially Time-of-Flight Secondary Ion Mass Spectrometry, further supported the existence of a core-shell structure in the products. Direct observation of macromolecules by means of cryogenic transmission electron microscopy, as well as gel permeation chromatography (GPC), suggested the existence of a minor 'aggregated' product fraction with multiple HPPA cores, which was attributed to transesterification reactions. Differential scanning calorimetry, as well as X-ray diffraction, demonstrated that the PCL-HPPA polymers displayed a similar degree of crystallinity to linear neat PCL, but that the branched products possessed smaller and less regular crystallites.

A Comprehensive Review on Processing, Development and Applications of Organofunctional Silanes and Silane-Based Hyperbranched Polymers

Since the last decade, hyperbranched polymers (HBPs) have gained wider theoretical interest and practical applications in sensor technology due to their ease of synthesis, highly branched structure but dimensions within nanoscale, a larger number of modified terminal groups and lowering of viscosity in polymer blends even at higher HBP concentrations. Many researchers have reported the synthesis of HBPs using different organic-based core-shell moieties. Interestingly, silanes, as organic-inorganic hybrid modifiers of HBP, are of great interest as they resulted in a tremendous improvement in HBP properties like increasing thermal, mechanical and electrical properties compared to that of organic-only moieties. This review focuses on the research progress in organofunctional silanes, silane-based HBPs and their applications since the last decade. The effect of silane type, its bi-functional nature, its influence on the final HBP structure and the resultant properties are covered in detail. Methods to enhance the HBP properties and challenges that need to be overcome in the near future are also discussed.

Azo-Functionalized Thermoplastic Polyurethane for Light-Driven Shape Memory Materials

Shape memory polymers have great potential in the fields of soft robotics, injectable medical devices, and as essential materials for advanced electronic devices. Herein, light-triggered shape-memory thermoplastic polyurethane (TPU) is reported using azido TPU grafted by the photoswitchable azo compound. The trans-cis transitions of the azobenzene on the side chain of the TPU induce the recoiling of the main chain, leading to shaping memory behavior. Under UV irradiation, cis-azo allows the oriented main chain to recoil to release residual stress and realize light-triggered shape memory behavior. The facile method proposed here for the preparation of azo-functionalized TPU can provide viable opportunities for soft robotics and smart TPU applications.

Mussel-Inspired Lego Approach for Controlling the Wettability of Surfaces with Colorless Coatings

The control of surface wettability with polyphenol coatings has been at the forefront of materials research since the late 1990s, when robust underwater adhesion was linked to the presence of L-DOPA-a catecholic amino acid-in unusually high amounts, in the sequences of several mussel foot proteins. Since then, several successful approaches have been reported, although a common undesired feature of most of them is the presence of a remnant color and/or the intrinsic difficulty in fine-tuning and controlling the hydrophobic character. We report here a new family of functional catechol-based coatings, grounded in the oxidative condensation of readily available pyrocatechol and thiol-capped functional moieties. The presence of at least two additional thiol groups in their structure allows for polymerization through the formation of disulfide bonds. The synthetic flexibility, together with its modular character, allowed us to: (I) develop coatings with applications exemplified by textiles for oil-spill water treatment; (II) develop multifunctional coatings, and (III) fine-tune the WCA for flat and textile surfaces. All of this was achieved with the application of colorless coatings.

Influence of cationic groups on the antibacterial behavior of cationic nano-sized hyperbranched polymers to enhance bacteria-infected wound healing

With the continuous emergence of drug-resistant pathogens, new strategies with high antibacterial efficacy are urgently needed. Herein, five cationic nano-sized hyperbranched polymers (CNHBPs) with cationic functional groups have been constructed, and their antibacterial mechanism has been studied in detail. CNHBPs bearing secondary ammonium salt groups and long alkyl chains (S₁₂-CNHBP) exhibited weak antibacterial and antibiofilm ability, while CNHBPs bearing quaternary ammonium salt groups and long alkyl chains (Q₁₂-CNHBP) showed the highest antimicrobial and strongest antibiofilm activities. ζ potential and isothermal titration microcalorimetry (ITC) results suggest that the negatively charged surfaces of bacterial cells provided Q₁₂-CNHBP with a higher intrinsic electrostatic driving force for bacterial killing than that with S₁₂-CNHBP. Fluorescent tracing and morphological observations indicate that the bacterial genome might be another antibacterial target for S₁₂-CNHBP in addition to the cell wall and membrane, which are mainly antibacterial targets for Q₁₂-CNHBP, making it less likely to induce bacterial resistance. Surprisingly, Q₁₂-CNHBP exhibited superior in vivo therapeutic efficacy in a mouse wound model of methicillin-resistant Staphylococcus aureus (MRSA) infection with low toxicity during treatment. These advantages and ease of preparation will undoubtedly distinguish Q₁₂-CNHBP as a new class of suitable candidates to combat multidrug-resistant pathogen infections. This study opens up a new avenue for exploiting antibacterial biomaterials to treat infections caused by drug-resistant bacteria.

Cluster Size of Amylopectin and Nanosized Amylopectin Fragments Characterized by Pyrene Excimer Formation

Amylopectin from waxy corn and the three nanosized amylopectin fragments (NAFs)—NAF(56), NAF(20), and NAF(8)—from waxy corn starch with a hydrodynamic diameter of 227, 56, 20, and 8 nm, respectively, were randomly labeled with 1-pyrenebutyric acid. The efficiency of these pyrene-labeled amylopectin-based polysaccharides (Py-AbPS) for pyrene excimer formation (PEF) upon diffusive encounter between an excited and a ground-state pyrene increased with increasing concentration of unlabeled NAF(56) in Py-AbPS dispersions in DMSO. Fluorescence decay analysis of the Py-AbPS dispersions in DMSO prepared with increasing [NAF(56)] yielded the maximum number (N_blob^exp) of anhydroglucose units (AGUs) separating two pyrene-labeled AGUs while still allowing PEF. Comparison of N_blob^exp with N_blob^theo, obtained by conducting molecular mechanics optimizations on helical oligosaccharide constructs with HyperChem, led to a relationship between the interhelical distance (d_h-h) in a cluster of oligosaccharide helices, [NAF(56)], and the number of helices in a cluster. It was found that the AbPSs were composed of building blocks made of 3.5 (±0.9) helices that self-assembled into increasingly larger clusters with increasing [NAF(56)]. The ability of PEF-based experiments to yield the cluster size of AbPSs provides a new experimental means to probe the interior of AbPSs at the molecular level.

Secondary Ammonium-Based Hyperbranched Poly(amidoamine) with Excellent Membrane-Active Property for Multidrug-Resistant Bacterial Infection

With the rapid emergence of microbial infections induced by "superbugs", public health and the global economy are threatened by the lack of effective and biocompatible antibacterial agents. Herein, we systematically design a series of secondary ammonium-based hyperbranched poly(amidoamine) (SAHBP) with different alkyl chain lengths for probing high-efficacy antibacterial agents. SAHBP modified with alkyl tails at the hyperbranched core could efficiently kill Escherichia coli and Staphylococcus aureus, two types of clinically important bacteria worldwide. The best SAHBP with 12-carbon-long alkyl tails (SAHBP-12) also showed high activity against problematic multidrug-resistant bacteria, including Pseudomonas aeruginosa and methicillin-resistant S. aureus (MRSA). Based on ζ potential, isothermal titration microcalorimetry (ITC), and membrane integrity assays, it is found that SAHBP-12 could attach to the cell membrane via electrostatic adsorption and hydrophobic interactions, following which the integrity of the bacterial cell wall and the cell membrane is disrupted, resulting in severe cell membrane damage and the leakage of cytoplasmic contents, finally causing bacterial cell death. Impressively, benefiting from excellent membrane-active property, SAHBP-12 exhibited robust therapeutic efficacy in MRSA-infected mice wounds. Moreover, SAHBP-12 also showed excellent biosafety in vitro and in vivo, which undoubtedly distinguished it as a potent weapon in combating the growing threat of problematic multidrug-resistant bacterial infections.

Enhancement of Epoxy Thermosets with Hyperbranched and Multiarm Star Polymers: A Review

Hyperbranched polymers and multiarm star polymers are a type of dendritic polymers which have attracted substantial interest during the last 30 years because of their unique properties. They can be used to modify epoxy thermosets to increase their toughness and flexibility but without adversely affecting other properties such as reactivity or thermal properties. In addition, the final properties of materials can be tailored by modifying the structure, molecular weight, or type of functional end-groups of the hyperbranched and multiarm star polymers. In this review, we focus on the modification of epoxy-based thermosets with hyperbranched and multiarm star polymers in terms of the effect on the curing process of epoxy formulations, thermal, mechanical, and rheological properties, and their advantages in fire retardancy on the final thermosets.

Recent Progress, Challenges, and Trends in Polymer-Based Sensors: A Review

Polymers are long-chain, highly molecular weight molecules containing large numbers of repeating units within their backbone derived from the product of polymerization of monomeric units. The materials exhibit unique properties based on the types of bonds that exist within their structures. Among these, some behave as rubbers because of their excellent bending ability, lightweight nature, and shape memory. Moreover, their tunable chemical, structural, and electrical properties make them promising candidates for their use as sensing materials. Polymer-based sensors are highly utilized in the current scenario in the public health sector and environment control due to their rapid detection, small size, high sensitivity, and suitability in atmospheric conditions. Therefore, the aim of this review article is to highlight the current progress in polymer-based sensors. More importantly, this review provides general trends and challenges in sensor technology based on polymer materials.

Hyperbranched polymers as superior adsorbent for the treatment of dyes in water

The effective control on environmental pollutants is crucial for the proper management of diverse environmental systems (e.g., soil, water, and air). In this respect, the utility of various functional materials such as hyperbranched polymers (HPs) has been recognized due to their great potentil as adsorbent for the mitigation of numerous environmental pollutants. Here, we highlight the latest progress achieved in the design and construction of HPs with high adsorption potentials. We focus on adsorption mechanisms, functionalization methods, the role of functional groups in adsorption capacity, and the choice of HPs in adsorption of cationic and anionic dyes. Recent published reports are reviewed to quantify and qualify the removal efficiency of pollutants through adsorption. We also evaluate the adsorbing efficiency of the constructed HPs and compared their performance with other such systems. The utilization potential of new materials (magnetic, polar, and biological) is highlighted along with the methods needed for their preparation and/or modification (surface, end-group, and zwitterionic) for the construction of efficient adsorbing systems. Finally, the advantages and limitations of adsorbing systems are described along with the existing challenges to help establish guidelines for future research. This article is thus expected to offer new path and guidance for developing advanced HP-based adsorbents.

Modification of carbon-based nanomaterials by polyglycerol: recent advances and applications

Hyperbranched polymers, a subclass of dendritic polymers, mimic nature's components such as trees and nerves. Hyperbranched polyglycerol (HPG) is a hyperbranched polyether with outstanding physicochemical properties, including high water-solubility and functionality, biocompatibility, and an antifouling feature. HPG has attracted great interest in the modification of different objects, in particular carbon-based nanomaterials. In this review, recent advances in the synthesis and application of HPG to modify carbon-based nanomaterials, including graphene, carbon nanotubes, fullerene, nanodiamonds, carbon dots, and carbon fibers, are reviewed.

Synthesis of Arylene Ether-Type Hyperbranched Poly(triphenylamine) for Lithium Battery Cathodes

We synthesized a new poly(triphenylamine), having a hyperbranched structure, and employed it in lithium-ion batteries as an organic cathode material. Two types of monomers were prepared with hydroxyl groups and nitro leaving groups, activated by a trifluoromethyl substituent, and then polymerized via the nucleophilic aromatic substitution reaction. The reactivity of the monomers differed depending on the number of hydroxyl groups and the A₂B type monomer with one hydroxyl group successfully produced poly(triphenylamine). Based on thermal, optical, and electrochemical analyses, a composite poly(triphenylamine) electrode was made. The electrochemical performance investigations confirmed that the lithium-ion batteries, fabricated with the poly(triphenylamine)-based cathodes, had reasonable specific capacity values and stable cycling performance, suggesting the potential of this hyperbranched polymer in cathode materials for lithium-ion batteries.

Cyclic ethylene phosphates with (CH2)nCOOR and CH2CONMe2 substituents: synthesis and mechanistic insights of diverse reactivity in aryloxy-Mg complex-catalyzed (co)polymerization

Herein we present a comparative study of the reactivity of ethylene phosphates with –O(CH2)nCOOMe (n = 1–3, 5), –CH2COOtBu, –OCHMeCOOMe, and –OCH2CONMe2 substituents in BHT-Mg catalyzed ROP.

Nanoengineering with RAFT polymers: from nanocomposite design to applications

Reversible addition–fragmentation chain-transfer (RAFT) polymerization is a powerful tool for the precise formation of macromolecular building blocks that can be used for the construction of well-defined nanocomposites.

Superbranched polyglycerol nanostructures as drug delivery and theranostics tools for cancer treatment

Hyperbranched polymers (HBPs), such as hyperbranched polyglycerols (HPGs) with a dendritic configuration, have been recognized for their excellent biocompatibility and multifunctionalization. HPGs have been studied for use in the delivery diagnostic, imaging and therapeutic molecules in the area of nanobiomedicine. They show superior characteristics to linear polymers and dendrimers, such as compact structure, a simple manufacturing process with easy functionalization ability, low viscosity, and high stability. Owing to these advantages, HPGs are now considered promising carriers for drug delivery, diagnostics, imaging, and theranostics applications for cancer treatment. In this review, we also discuss safety aspects of HPG-based nanoformulations in various animal models and the clinical translation status of such polymers for real-time applications.

Recent advances in development of dendritic polymer-based nanomedicines for cancer diagnosis

Dendritic polymers have highly branched three-dimensional architectures, the fourth type apart from linear, cross-linked, and branched one. They possess not only a large number of terminal functional units and interior cavities, but also a low viscosity with weak or no entanglement. These features endow them with great potential in various biomedicine applications, including drug delivery, gene therapy, tissue engineering, immunoassay and bioimaging. Most review articles related to bio-related applications of dendritic polymers focus on their drug or gene delivery, while very few of them are devoted to their function as cancer diagnosis agents, which are essential for cancer treatment. In this review, we will provide comprehensive insights into various dendritic polymer-based cancer diagnosis agents. Their classification and preparation are presented for readers to have a precise understanding of dendritic polymers. On account of physical/chemical properties of dendritic polymers and biological properties of cancer, we will suggest a few design strategies for constructing dendritic polymer-based diagnosis agents, such as active or passive targeting strategies, imaging reporters-incorporating strategies, and/or internal stimuli-responsive degradable/enhanced imaging strategies. Their recent applications in in vitro diagnosis of cancer cells or exosomes and in vivo diagnosis of primary and metastasis tumor sites with the aid of single/multiple imaging modalities will be discussed in great detail. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Diagnostic Tools > in vivo Nanodiagnostics and Imaging Diagnostic Tools > in vitro Nanoparticle-Based Sensing.

Hydrolytic Degradation of Comb-Like Graft Poly (Lactide-co-Trimethylene Carbonate): The Role of Comonomer Compositions and Sequences

The effect of sequence on copolymer properties is rarely studied, especially the degradation behavior of the biomaterials. A series of linear-comb block, gradient, random copolymers were successfully achieved using hydroxylated polybutadiene as the macroinitiator by simple ring-opening polymerization of l-lactide (l-LA) and 1,3-trimethylene carbonate (TMC). The hydrolytic degradation behaviors of the copolymers were systemically evaluated by using nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), differential scanning calorimeter (DSC), and scanning electron microscopy (SEM) to illustrate the influences of comonomer compositions and sequence structures. The linear-comb block copolymers (lcP(TMC-b-LLA)) with different compositions had different degradation rates, which increased with l-LA content. Thermal property changes were observed with decreased T_m and increased ΔH_m in all block copolymers during the degradation. To combine different sequence structures, unique degradation behaviors were observed for the linear-comb block, gradient and random copolymers even with similar comonomer composition. The degradation rates of linear-comb PLLA-gradient-PTMC (lcP(LLA-grad-TMC)) and linear-comb PLLA-random-PTMC (lcP(LLA-ran-TMC)) were accelerated due to the loss of regularity and crystallinity, resulting in a remarkable decrease on weight retention and molar mass. The hydrolysis degradation rate increased in the order lcP(TMC-b-LLA), lcP(LLA-ran-TMC), lcP(LLA-grad-TMC). Therefore, the hydrolytic degradation behavior of comb-like graft copolymers depends on both the compositions and the sequences dramatically.

Design and Synthesis of Hyperbranched Aromatic Polymers for Catalysis

Aromatic polymers such as poly(ether sulfone), poly(ether ketone), and polyimide have been widely used in industry due to their thermal, mechanical, and chemical stabilities. Although their application to catalysis has been limited, the introduction of a hyperbranched architecture to such aromatic polymers is effective in developing catalytic materials that combine the advantages of homogenous and heterogeneous catalysts. This review article overviews the recent progress on the design and synthesis of hyperbranched aromatic polymers. Several acid catalyzed reactions and the aerobic oxidation of alcohols have been demonstrated using hyperbranched aromatic polymers as catalysts. The advantage of hyperbranched polymers against linear polymers is also discussed.