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Switchable polymerization holds considerable potential for the synthesis of highly sequence-controlled multiblock. To date, this method has been limited to three-component systems, which enables the straightforward synthesis of multiblock polymers with less than five blocks. Herein, we report a self-switchable polymerization enabled by simple alkali metal carboxylate catalysts that directly polymerize six-component mixtures into multiblock polymers consisting of up to 11 blocks. Without an external trigger, the catalyst polymerization spontaneously connects five catalytic cycles in an orderly manner, involving four anhydride/epoxide ring-opening copolymerizations and one L-lactide ring-opening polymerization, creating a one-step synthetic pathway. Following this autotandem catalysis, reasonable combinations of different catalytic cycles allow the direct preparation of diverse, sequence-controlled, multiblock copolymers even containing various hyperbranched architectures. This method shows considerable promise in the synthesis of sequentially and architecturally complex polymers, with high monomer sequence control that provides the potential for designing materials. Switchable polymerization holds considerable potential for the synthesis of highly sequence-controlled multiblock. Here the authors show a self-switchable polymerization enabled by simple alkali metal carboxylate catalysts that directly polymerize six component mixtures into polymers consisting of up to 11 blocks.

Nano-sized metal particles are attracting much interest in industrial and biomedical applications due to the recent progress and development of nanotechnology, and the surface-modifications by appropriate polymers are key techniques to stably express their characteristics. Herein, we applied cyclic poly(ethylene glycol) ( c -PEG), having no chemical inhomogeneity, to provide a polymer topology-dependent stabilization for the surface-modification of gold nanoparticles (AuNPs) through physisorption. By simply mixing c -PEG, but not linear counterparts, enables AuNPs to maintain dispersibility through freezing, lyophilization, or heating. Surprisingly, c -PEG endowed AuNPs with even better dispersion stability than thiolated PEG (HS–PEG–OMe). The stronger affinity of c -PEG was confirmed by DLS, ζ-potential, and FT-IR. Furthermore, the c -PEG system exhibited prolonged blood circulation and enhanced tumor accumulation in mice. Our data suggests that c -PEG induces physisorption on AuNPs, supplying sufficient stability toward bio-medical applications, and would be an alternative approach to the gold–sulfur chemisorption. Many nanoparticles are stabilised by chemical functionalisation with poly(ethylene glycol) (PEG). Here, the authors report on the functionalisation of gold nanoparticles by the physical absorption of cyclic PEG and demonstrate superior stabilisation against heating, freezing and lyophilisation.

The first polyhydroxyalkanoate (PHA) block copolymer poly(2-hydroxybutyrate- b -3-hydroxybutyrate) [P(2HB- b -3HB)] was previously synthesized using engineered Escherichia coli expressing a chimeric PHA synthase PhaC AR with monomer sequence-regulating capacity. In the present study, the physical properties of the block copolymer and its relevant random copolymer P(2HB- ran -3HB) were evaluated. Stress–strain tests on the P(88 mol% 2HB- b -3HB) film showed an increasing stress value during elongation up to 393%. In addition, the block copolymer film exhibited slow contraction behavior after elongation, indicating that P(2HB- b -3HB) is an elastomer-like material. In contrast, the P(92 mol% 2HB- ran -3HB) film, which was stretched up to 692% with nearly constant stress, was stretchable but not elastic. The differential scanning calorimetry and wide-angle X-ray diffraction analyses indicated that the P(2HB- b -3HB) contained the amorphous P(2HB) phase and the crystalline P(3HB) phase, whereas P(2HB- ran -3HB) was wholly amorphous. Therefore, the elasticity of P(2HB- b -3HB) can be attributed to the presence of the crystalline P(3HB) phase and a noncovalent crosslinked structure by the crystals. These results show the potential of block PHAs as elastic materials.

Conjugated polymer nanoparticles (CP NPs) attract attention as nanoscale materials used for a variety of applications. In relation to this, the internal structure of CP NPs is an important factor for their properties, and numerous investigations have been carried out to control their nanomorphology. Here, we report the formation of CP NPs from defect-free cyclic poly(3-hexylthiophene) (c-P3HT) using a microfluidic device, and the effect of polymer topology on their structural and solvatochromic properties was investigated. CP NPs from c-P3HT exhibited reduced particle sizes and hypsochromic shifts in the absorption spectrum when compared to CP NPs obtained from corresponding linear P3HT (l-P3HT). Furthermore, steady responses in the solvatochromism of CP NPs from c-P3HT were observed, while those from l-P3HT displayed molecular weight dependency. These topology effects were caused by the change in the conjugation length, solubility, and crystallinity upon cyclization. Grazing incidence X-ray scattering (GIXS) studies of spin-coated P3HT films further showed a reduced interchain order and a larger proportion of face-on molecular orientation on a substrate for c-P3HTs. The various distinct structures observed for c-P3HT indicate the use of polymer topology as a means of nanostructure regulation.

Heat dissipation has become increasingly important in electronics. Conventional convection cooling systems have significant material and dimensional constraints, and they have difficulty meeting the heat dissipation, miniaturization, and flexibility requirements of next-generation smart electronics. Here, we used kirigami (the traditional art of paper cutting) with a thermally conductive cellulose nanofiber film to propose a flexible cooling system through convective heat dissipation. By stretching the Amikazari (net decoration) pattern produced by kirigami and allowing air convection through its aperture at 3.0 m/s, the thermal resistance was reduced to approximately one-fifth of that without kirigami and convection. The kirigami apertures defined the outlet air velocity, resulting in a significant increase in the heat-transfer coefficient. Our kirigami heat dissipation concept enables the design of electronics using a variety of film materials as shape-variant cooling structures, which will inspire a wide range of thermal engineering and electronics applications.A shape-variant heat dissipation system using kirigami was proposed using the thermally conductive cellulose nanofiber films. By stretching the Amikazari (net decoration) pattern produced by kirigami and allowing air convection through its aperture at 3.0m/s, the thermal resistance was reduced to approximately one-fifth of that without kirigami and convection. The periodic apertures of kirigami defined the outlet air velocity of convection, resulting in a significant increase in the heat-transfer coefficient. We further demonstrated the effective cooling of the kirigami-processed powder electroluminescent device during the emission of light.

Carbohydrates constitute a sustainable source of materials that has attracted growing interest due to their “green” aspects, biocompatibility, biodegradability and biorecognition properties. Their industrial applications at the macroscopic scale offer new solutions for biobased materials, and they have been applied in different sectors, such as cosmetics, health, packaging, or microelectronics. To gain more understanding and incorporate these systems into new challenges/applications and devices (e.g., bionanoelectronics) in response to the transition to a biobased economy, it is of great importance to control their self-assembly at the nanoscale. This has been the aim of our work during the past decade—we have used “click chemistry” and developed a new class of linear carbohydrate-based (so-called high χ) diblock copolymer systems resulting, via self-assembly, in highly nanostructured sub-10-nm-resolution thin films. In this focused review, we summarize some recent work illustrating the self-assembly properties leading to the design of glyconanoparticles and highly nanostructured thin films potentially of great importance in different applications and biomarkers.The self-assembly of carbohydrate-based block copolymer systems has allowed recently the conception of novel glyconanoparticles and high-resolution patterning thin films with sub_10nm resolution (high χ) that has never been attained by petroleum-based copolymers and provides these new nanostructured biomaterials with novel properties such as next generation nanolithography, memory devices, OPV and biosensors. The glyconanoparticles can be designed to meet the targeted applications in terms of size, encapsulation and decoration. The control of the lamellar/cylindrical phases orientation can be achieved using thermal, solvent vapor or microwave annealing processes in thin films.

Silver nanoparticles (AgNPs) are used in a wide range of applications, and the size control and stability of the nanoparticles are crucial aspects in their applications. In the present study, cyclized poly(ethylene glycol) (c-PEG) with various molecular weights, along with linear PEG with hydroxy chain ends (HO–PEG–OH) and methoxy chain ends (MeO–PEG–OMe) were applied for the Tollens’ synthesis of AgNPs. The particle size was significantly affected by the topology and end groups of PEG. For example, the size determined by TEM was 40 ± 7 nm for HO–PEG5k–OH, 21 ± 4 nm for c-PEG5k, and 48 ± 9 nm for MeO–PEG5k–OMe when the molar ratio of PEG to AgNO3 (ω) was 44. The stability of AgNPs was also drastically improved by cyclization; the relative UV–Vis absorption intensity (A/A0 × 100%) at λmax to determine the proportion of persisting AgNPs in an aqueous NaCl solution (37.5 mM) was 58% for HO–PEG5k–OH, 80% for c-PEG5k, and 40% for MeO–PEG5k–OMe, despite the fact that AgNPs with c-PEG5k were much smaller than those with HO–PEG5k–OH and MeO–PEG5k–OMe.

Dispersion stabilization of nanoparticles for catalytic reactions is an important issue. However, dispersing agents should be carefully selected not to hinder catalytic performance. In the present study, physisorption of cyclic poly(ethylene glycol) (c-PEG) onto platinum nanoparticles (PtNPs) was investigated in comparison with unmodified PtNPs (PtNPs/No PEG), PtNPs mixed with linear PEG (PtNPs/HO-PEG-OH), and PtNPs chemisorbed with HS-PEG-OMe (PtNPs/HS-PEG-OMe). DLS showed a significant increase in the particle size for PtNPs/c-PEG and PtNPs/HS-PEG-OMe compared to PtNPs/No PEG and PtNPs/HO-PEG-OH. ζ-potential measurements revealed values around −30 mV for PtNPs/No PEG and PtNPs/HO-PEG-OH, whereas PtNPs/c-PEG and PtNPs/HS-PEG-OMe approached 0 mV, which indicated that c-PEG and HS-PEG-OMe adsorb onto PtNPs to form a shielding layer. Moreover, PtNPs/c-PEG and PtNPs/HS-PEG-OMe were stable in a phosphate-buffered saline (PBS) solution, but PtNPs/No PEG and PtNPs/HO-PEG-OH immediately aggregated. This suggests that high dispersion stability by c-PEG is comparable to ordinary surface modification using HS-PEG-OMe. Furthermore, the catalytic ability of PtNPs/c-PEG and PtNPs/HS-PEG-OMe was compared in various reactions. As a result, physisorbed PtNPs/c-PEG showed suitable catalytic activities, whereas chemisorbed PtNPs/HS-PEG-OMe was significantly hampered by the blocking of the catalytic sites with thiol in some reactions. Thus, physisorption of c-PEG endows PtNPs with dispersion stability and maintains the catalytic ability, leading to an alternative way of modifying metal nanoparticles.

To induce potent epitope-specific T cell immunity by a peptide-based vaccine, epitope peptides must be delivered efficiently to antigen-presenting cells (APCs) in vivo. Therefore, selecting an appropriate peptide carrier is crucial for the development of an effective peptide vaccine. In this study, we explored new peptide carriers which show enhancement in cytotoxic T lymphocyte (CTL) induction capability. Data from an epitope-specific in vivo CTL assay revealed that phosphatidylserine (PS) has a potent adjuvant effect among candidate materials tested. Further analyses showed that PS-conjugated antigens were preferentially and efficiently captured by professional APCs, in particular, by CD11c(+)CD11b(+)MHCII(+) conventional dendritic cells (cDCs) compared to multilamellar liposome-conjugates or unconjugated antigens. In addition, PS demonstrated the stimulatory capacity of peptide-specific helper T cells in vivo. This work indicates that PS is the easily preparable efficient carrier with a simple structure that delivers antigen to professional APCs effectively and induce both helper and cytotoxic T cell responses in vivo. Therefore, PS is a promising novel adjuvant for T cell-inducing peptide vaccines.

Micelles were prepared in organic solvents by using three topological polymer amphiphiles: (i) cyclic poly(n-decyl glycidyl ether-block-2-(2-(2-methoxyethoxy)ethoxy)ethyl glycidyl ether) (c-PDGE-b-PTEGGE) and (ii) its linear analogue (l-PDGE-b-PTEGGE); (iii) linear poly(6-phosphorylcholinehexylthiopropyl glycidyl ether-block-n-dodecanoyl glycidyl ether) (l-PPCGE-b-PDDGE). For the individual micelle solutions, the size and distribution were determined by dynamic light scattering (DLS) and synchrotron X-ray scattering analyses. The synchrotron X-ray scattering analysis further found that c-PDGE-b-PTEGGE forms oblate ellipsoidal micelle in an ethanol/water mixture, l-PDGE-b-PTEGGE makes prolate ellipsoidal micelle in an ethanol/water mixture, and l-PPCGE-b-PDDGE forms cylindrical micelle in chloroform. This comparative study found that there are large differences in the size and distribution results extracted by DLS and X-ray scattering analyses. All possible factors to cause such large differences are discussed. Moreover, a better use of the DLS instrument with keeping its merits is proposed.