Dendritic and hyperbranched polyamides

Polyoxyethylene Diamine Modification of Poly(amide-imide)-polyethylene Glycol Exhibits Excellent Hydrophilicity, Degradability, and Biocompatibility

We designed and synthesized the polyoxyethylene diamine (H2N-PEG-NH2) and poly(amide-imide)-polyethylene glycol (PAI-PEG) copolymers. The physical and chemical properties, mechanical properties, and in vitro biocompatibility of the materials were characterized. The results showed that the best elongation at break and recovery were obtained when the amount of PEG was 5 wt%. With the increase in PEG content, the degradation rate, hydrophilic property, tensile strength and tensile modulus of the copolymer decreased to a certain extent. The material had the best thermal stability and mechanical properties when 5 wt% PEG was added. Cytocompatibility evaluation showed that the addition of PEG could enhance the cell compatibility of the material and make it potentially suitable for application in bone repair.

Synthesis, optical, electrochemical properties and anticancer activity of (S)-BINOL cored triazole bridged dendrimers decorated with rhodamine B surface group

(S)-BINOL cored dendrimers 1–3 with a rhodamine B surface group and triazole bridging unit were synthesized up to second generation in good yield by convergent synthesis through click chemistry. The chiro-optical property of the synthesized dendrimers reveals that the specific rotation increases as the order of dendrimer increases from the zeroth generation to the second generation dendrimer. The electrochemical properties of the dendrimers 1, 2 and 3 showed quasi-reversible behavior in cyclic voltammetry. The anticancer activity against human hepatocellular carcinoma cell for the second generation dendrimer 3 was found to be better than that for the lower generation dendrimers 1 and 2.

(S)-BINOL cored dendrimers 1–3 with rhodamine B surface group and triazole bridging unit were synthesized up to second generation in good yield by convergent synthesis through click chemistry.

Study of Hyperbranched Poly(ethyleneimine) Polymers of Different Molecular Weight and Their Interaction with Epoxy Resin

Two different commercial hyperbranched poly(ethyleneimine)s (HBPEI), with molecular weights (MW) of 800 and 25,000 g/mol, and denoted as PEI800 and PEI25000, respectively, as well as the mixtures with a Diglycidyl Ether of Bisphenol-A (DGEBA) epoxy resin, have been studied using thermal analysis techniques (DSC, TGA), dielectric relaxation spectroscopy (DRS), and dynamic mechanical analysis (DMA). Only a single glass transition is observed in these mixtures by DSC. DRS of the HBPEIs shows three dipolar relaxations: γ, β, and α. The average activation energy for the γ-relaxation is similar for all HBPEIs and is associated with the motion of the terminal groups. The β-relaxation has the same average activation energy for both PEI800 and PEI25000; this relaxation is attributed to the mobility of the branches. The α-relaxation peak for all the HBPEIs is an asymmetric peak with a shoulder on the high temperature side. This shoulder suggests the existence of ionic charge trapped in the PEI. For the mixtures, the γ- and β-relaxations follow the behaviour of the epoxy resin alone, indicating that the epoxy resin dominates the molecular mobility. The α-relaxation by DRS is observed only as a shoulder, as a consequence of an overlap with conductivity effects, whereas by DMA, it is a clear peak.

Polypeptide self-assemblies: nanostructures and bioapplications

Polypeptide copolymers can self-assemble into diverse aggregates. The morphology and structure of aggregates can be varied by changing molecular architectures, self-assembling conditions, and introducing secondary components such as polymers and nanoparticles. Polypeptide self-assemblies have gained significant attention because of their potential applications as delivery vehicles for therapeutic payloads and as additives in the biomimetic mineralization of inorganics. This review article provides an overview of recent advances in nanostructures and bioapplications related to polypeptide self-assemblies. We highlight recent contributions to developing strategies for the construction of polypeptide assemblies with increasing complexity and novel functionality that are suitable for bioapplications. The relationship between the structure and properties of the polypeptide aggregates is emphasized. Finally, we briefly outline our perspectives and discuss the challenges in the field.

Functional Aromatic Polyamides

We describe herein the state of the art following the last 8 years of research into aromatic polyamides, wholly aromatic polyamides or aramids. These polymers belong to the family of high performance materials because of their exceptional thermal and mechanical behavior. Commercially, they have been transformed into fibers mainly for production of advanced composites, paper, and cut and fire protective garments. Huge research efforts have been carried out to take advantage of the mentioned characteristics in advanced fields related to transport applications, optically active materials, electroactive materials, smart materials, or materials with even better mechanical and thermal behavior.

Phototriggered Ring-Opening Polymerization of a Photocaged l-Lysine N-Carboxyanhydride to Synthesize Hyperbranched and Linear Polypeptides

Increasing efforts are being made on controlled photopolymerization methodologies; however, the previous polymerization systems need additional photoactive initiators or catalysts. The controlled synthesis of the hyperbranched polypeptide is still challenging, and developing a photopolymerization method to prepare a hyperbranched polypeptide is urgent for constructing biodegradable polymers and biomaterials. Without addition of any initiator/catalyst, we combine the inimer (initiator + monomer) ring-opening polymerization (ROP) and photocaged chemistry to prepare hyperbranched and linear polypeptides. The photocaged Nε-(o-nitrobenzyloxycarbonyl)-l-lysine-N-carboxyanhydride possesses intrinsic photosensitivity and will be transformed into an activated AB* inimer-type α-amino acid N-carboxyanhydride (NCA) containing a primary ε-amine, which further triggers ROP to produce linear and/or hyperbranched polypeptides in one pot and at room temperature. The microstructure and topology of the resulting polypeptide were clarified by means of mass spectroscopy and various NMR techniques including ¹H NMR, ¹H, ¹H-COSY, and quantitative ¹³C NMR. By tuning the UV irradiation time or intensity, this methodology can produce a linear polypeptide with a high M_w,GPC of 109 kDa and/or (hyper)branched counterparts with tunable M_w,GPC's of 1.4-73.5 kDa and degree of branching of 0.09-0.60.

Computer Simulation Studies on the pH-Responsive Self-Assembly of Amphiphilic Carboxy-Terminated Polyester Dendrimers in Aqueous Solution

This paper investigates the pH-responsive self-assembly of an amphiphilic carboxyl-terminated polyester dendrimer, H20-COOH, in aqueous solution using the dissipative particle dynamics method. The electrostatic interactions were described by introducing the explicit interaction between the smeared charges on ionized polymer beads and the counterions. The results show that the self-assemblies could change from unimolecular micelles, microphase-separated small micelles, wormlike micelles, sheetlike micelles, and small vesicles to large vesicles with the decrease in the degree of ionization (α) of carboxylic acid groups. In addition, the detailed self-assembly mechanisms and the molecular packing models have also been disclosed for each self-assembly stages. Interestingly, the wormlike micelles are found to change from linear to branched when α decreases from 0.182 to 0.109. The current work might serve as a comprehensive understanding on the effect of carboxylic acid groups on the self-assembly behaviors of dendritic polymers.

Reduction- and thermo-sensitive core-cross-linked polypeptide hybrid micelles for triggered and intracellular drug release

To address the dynamic instability, premature burst drug release, and lack of intracellular stimuli-sensitivity of current polymeric nanocarriers, a novel type of reduction- and thermo-sensitive core-cross-linked polypeptide hybrid micelle was developed.

Synthetic Biomaterials from Metabolically Derived Synthons

The utility of metabolic synthons as the building blocks for new biomaterials is based on the early application and success of hydroxy acid based polyesters as degradable sutures and controlled drug delivery matrices. The sheer number of potential monomers derived from the metabolome (e.g., lactic acid, dihydroxyacetone, glycerol, fumarate) gives rise to almost limitless biomaterial structural possibilities, functionality, and performance characteristics, as well as opportunities for the synthesis of new polymers. This review describes recent advances in new chemistries, as well as the inventive use of traditional chemistries, toward the design and synthesis of new polymers. Specific polymeric biomaterials can be prepared for use in varied medical applications (e.g., drug delivery, tissue engineering, wound repair, etc.) through judicious selection of the monomer and backbone linkage.

Cu(i)-Catalyzed amino-yne click polymerization

The first example of Cu(i)-catalyzed regio-specific and stereo-selective amino-yne click polymerization was established.

NIR-responsive polypeptide copolymer upconversion composite nanoparticles for triggered drug release and enhanced cytotoxicity

Near infrared light-responsive polypeptide copolymer upconversion composite nanoparticles exhibited controllable drug release and triggered cytotoxicity useful for on-demand drug delivery and cancer therapy.

Comb-like poly(l-cysteine) derivatives with different side groups: synthesis via photochemistry and click chemistry, multi-responsive nanostructures, triggered drug release and cytotoxicity

A series of comb-like graft polypeptides having different side groups and tunable grafting ratios were prepared by sequential photocleavage reactions and Michael-type thiol–ene addition, which provides a promising platform for on-demand nanomedicine and cancer therapy.

One-pot two polymers: ABB′ melt polycondensation for linear polyesters and hyperbranched poly(ester-urethane)s based on natural l-amino acids

One-pot two polymers: a novel one-pot temperature selective polymerization reaction was developed for ABB′ type multifunctional l-amino acid monomers to produce spherical hyperbranched poly(ester-urethane)s and helical linear polyesters.

Bioapplications of hyperbranched polymers

The recent research progress in biological and biomedical applications of hyperbranched polymers has been summarized in this review.

Hyperbranched polymers: advances from synthesis to applications

This review summarizes the advances in hyperbranched polymers from the viewpoint of structure, click synthesis and functionalization towards their applications in the last decade.

Triptycene based organosoluble polyamides: synthesis, characterization and study of the effect of chain flexibility on morphology

Triptycene based thermally stable, organosoluble and low viscous polyamides have been prepared. Polymers may be categorized as self-extinguishing materials. Relation between structural flexibility and surface morphology has been studied.