A supramolecular polymer gel is formed by host-guest interactions between a DB24C8-based bis(crown ether) and a copolymer containing the dibenzylammonium moiety. The formation of the gel and its cross-linked networks structure are evidenced by ¹H NMR spectroscopy, viscometry, and SEM. Interestingly, the gel shows both pH- and thermoesponsive behaviors, and excellent self-healing properties. The self-healing property of the gel is tested by rheological measurements, and it can also be seen visually and directly. The presented work provides a new strategy for the construction of the self-healing supramolecular polymer gels with potential applications in smart materials.

A supramolecular polymer gel is formed by host–guest interactions between a DB24C8-based bis(crown ether) and a copolymer containing the dibenzylammonium moiety. The gel shows both pH- and thermoresponsive behaviors, and excellent self-healing properties.

A new poly(3-butylthiophene) derivative with one terminus functionalized with a 1H,1H,2H,2H,3H,3H-perfluoroundecyl group (P3BT-F₁₇) is synthesized by Ni-catalyzed quasi-living polymerization and the subsequent quenching of living ends by allyl-Grignard reagent and the attachment of a fluoroalkyl chain. The quantitative introduction of fluoroalkyl chain ends is confirmed by matrix-assisted laser desorption/ionization time-of-flight–mass spectrometry (MALDI-TOF-MS), gel-permeation chromatography (GPC), ¹H NMR spectroscopy, and X-ray photoelectron spectroscopy (XPS). The electronic properties of P3BT-F₁₇ in solution and its crystalline structure in the solid state are investigated by UV–vis spectroscopy and cyclic voltammetry (CV), and by DSC and X-ray diffraction (XRD) analyses.

End-fluoroalkylated poly(3-buthylthiophene) with a well-defined structure and narrow molecular-weight distribution is successfully synthesized by quasi-living polymerization and fluoroalkylation on one end only. This polymer may be useful for controlling the surface and interfacial properties of semiconducting thin films, as demonstrated by the decrease of the contact angle of the solutions.

The successful stereospecific living cationic polymerization of α-methylstyrene (α-MeSt) using FeCl₃-based initiator systems at 0 °C is reported. Linear first-order ln([M]₀/[M]) vs. time and linear molecular weight vs. conversion plots suggest that the polymerization is living in nature, which is further confirmed from successful chain-extension experiments. Poly(α-methylstyrene)s of varying syndiotacticities (59.1% to 79.2%) and controllable molecular weights (4300–32 100 g mol⁻¹) with moderately narrow polydispersity indices (PDIs ≈1.3) are synthesized simply by varying the monomer-to-initiator ratio ([M]₀/[I]₀). A possible mechanism for this stereospecific polymerization is proposed. The glass-transition temperature and thermal-decomposition temperature depend on the syndiotacticity of poly(α-methylstyrene).

Poly(α-methylstyrene)s of varying syndiotacticity (59.1% to 79.2%) and controllable molecular weight (M_n = 4300–32 100 g mol⁻¹) with moderately narrow polydispersity indices (PDI ≈1.3) are synthesized via stereospecific living cationic polymerization of α-methylstyrene using an FeCl₃-based initiating system at 0 °C. The glass-transition temperature and the thermal stability are found to depend on the syndiotacticity of the as-synthesized poly(α-methylstyrene).

Platinum(II) polyyne polymers containing thiophene-acceptor-thiophene units are synthesized, and their main chain alkynes are functionalized by the formal cycloaddition–retro-electrocyclization reaction with tetracyanoethylene (TCNE). The polymer energy levels are significantly decreased by the TCNE addition. Bulk-heterojunction solar cells are fabricated using the TCNE-adducted platinum(II) polyyne polymers. The use of these polymers as p-type semiconductors in combination with n-type fullerene derivatives indicates that the p-type semiconducting ability decreases by approximately five to ten times after the TCNE addition. On the contrary, when the TCNE-adducted polymers are employed as a substitute for the fullerene derivatives, the all-polymer solar cells are initially fabricated.

Formal cycloaddition–retro-electrocyclization reactions between platinum(II) polyyne polymers and tetracyanoethylene (TCNE) successfully lower the polymer energy levels. Application of these polymers to p-type semiconducting materials in bulk-heterojunction solar cells suggests that the p-type performance decreases by approximately 5 to 10 times. Moreover, when a TCNE-adducted polymer is employed as an n-type semiconducting material, the generation of weak photocurrent is achieved.

Syndiotactic polystyrene (sPS) forms cocrystals with a variety of chemical compounds. The guest molecules can be easily replaced with other kinds of molecules under certain conditions. The guest-exchange process, on exposure to liquid triethylene glycol dimethyl ether (TEGDME), is followed by time-resolved simultaneous small-angle and wide-angle X-ray scattering to clarify the structure changes in molecular-level and higher-order structures. It is clarified that the exchange from the original guest chloroform to the new guest TEGDME takes place mainly after a certain incubation time, in parallel with the expansion of the lamellar period. The occurrence of the ϵ cocrystal during this process and the influence of the amount of chloroform on the incubation time are also studied.

Simultaneous small-angle and wide-angle X-ray scattering is applied to the guest-exchange phenomenon of syndiotactic-polystyrene cocrystals with chloroform on exposure to a liquid triethylene glycol dimethyl ether. It is found that a fully fledged guest-exchange process starts after an incubation time, accompanied by a significant expansion of the lamellar period and the occurrence of the ϵ cocrystal.

This paper reports a facile approach for fabricating core-shell structured graphene oxide (GO)-wrapped amine-modified poly(glycidyl methacrylate) (ami-PGMA) microspheres. The resulting core-shell structure is confirmed by scanning electron micsroscopy (SEM) and transmission electron microscopy (TEM), whereas the coexistence of GO and PGMA is confirmed by FTIR spectroscopy. The thermal stability of the ami-PGMA/GO microspheres is enhanced compared with that of pure PGMA microspheres. The novel ami-PGMA/GO composite microsphere-based electrorheological (ER) fluid shows typical ER characterization, using a rotational rheometer under an applied electric field. The dielectric analysis results along with the relaxation time and achievable polarizability of the fluid are correlated with the ER performance using a LCR meter.

Core–shell structured graphene oxide-wrapped amine-modified poly(glycidyl methacrylate) composite microspheres are fabricated through an amine-epoxide/carboxyl chemical reaction and then dispersed in silicone oil for an electrorheological fluid. When an electric field is applied, the dispersed particles form chains over the electrode, resulting in a solid-like behavior with a yield stress.

In the field of bioactive biomaterials, multi-biopolymer systems are of particular interest as they represent potential extra cellular matrix (ECM) mimics. Ternary mixtures composed of alginate, hyaluronan, and a lactose-modified chitosan undergo a rheological investigation that reveal the presence of polyanion-polycation supramolecular structures, which dissolve once the third (polyanion) component is added. Two selected ternary mixtures are used for the preparation of calcium–alginate hydrogels and their mechanical performance and stability are found to be strongly influenced by the relative composition in terms of the two non-gelling components. The presence in the mixture of bioactive polysaccharides leads to a notable improvement in the proliferation of primary culture of chondrocytes.

Alginate–hyaluronan-modified chitosan ternary mixtures in concentrated solution and hydrogel state show the presence of supramolecular complexes with inhomogeneity in elastic response and stimulate primary chondrocyte proliferation.

The synthesis of redox-sensitive poly(p-phenylene ethynylene)s (rsPPEs) bearing protected quinones in their backbone by the Sonogashira coupling reaction is described. The rsPPEs show excellent solubility in toluene, tetrahydrofurane, and chloroform. Cleavage of the protection group of the incorporated quinone moieties enables main-chain conductive polymers having redox-sensitive properties to be produced. These redox-sensitive switches can be reduced and oxidized in solution, as well as in the solid state, accompanied by a change of the photoluminescence values. The processes occurring during oxidation and reduction are analyzed by UV–vis and photoluminescence spectroscopy and lead to a decrease of intensity of 80% during oxidation. Such multifunctional polymers may be useful for redox-potential changing stimuli in biological systems.

Poly(p-phenylene ethynylene)s (PPEs) with reactive methoxy-substituted moieties are synthesized by the Sonogashira cross-coupling reaction and are used to generate quinone functionalities in the polymer backbone. The polymers can be reversibly reduced to hydroquinones and oxidized to quinones. Optical properties such as fluorescence are comparable to regular PPEs, whereby fluorescence is quenched in the quinone stage.

The crystal structure of syndiotactic polystyrene (sPS) co-crystals of δ-class is discussed with the aim of identifying molecular descriptors that allow predicting the lattice distortions induced by the inclusion of guest molecules inside the cavities of the nanoporous δ-form. Based on the consideration that monoclinic and triclinic clathrates and intercalates of sPS form as a result of the unique deformability of the cavities of the δ-form, the identified parameters are the fractional occupancy factors of the undeformed cavity of the δ-form from guests along the a-axis, the c-axis, and the normal to the (010) planes of the crystals, and the relative orientation of the guests to the chain axes.

The formation of the numerous δ-clathrates and intercalates of syndiotactic polystyrene is the result of the unique compliance of the cavities of the parent nanoporous δ-form. This compliance relies on a cooperative mechanism in which the host shapes the cavity around the guest, whereas the guest adopts conformations and orientations that comply with the geometry of the cavity at low cost of energy.

Concentrated nitric acid-treated multiwalled carbon nanotubes (MWCNTs) are functionalized with active poly(4-chloromethyl styrene) (PCMS) through the esterification reaction of the carboxyl groups of the former and the p-benzyl chloride groups of the latter in the presence of a phase-transfer catalyst. Characterization using Raman spectroscopy, Fourier transform infrared spectroscopy, and hydrogen nuclear magnetic resonance spectroscopy demonstrates that the active PCMS chains are chemically tethered onto the side walls (or surfaces) of the MWCNTs. The core-shell nanostructure of active PCMS-modified MWCNTs (MWCNT-PCMS) can be observed by high resolution transmission electron microscopy, and the amount of PCMS present is 31.3 wt% by thermogravimetric analysis. Solubility testing shows that MWCNT-PCMS dissolves well in tetrahydrofuran, chloroform, toluene, and N,N-dimethylformamide, and the maximum nanotube concentration in toluene is 413 mg L⁻¹.

Poly(4-chloromethyl styrene) (PCMS)-modified multiwalled carbon nanotubes (MWCNTs) (MWCNT-PCMS) are synthesized via a phase-transfer reaction and characterized. They have a core-shell structure and good solubility in organic solvents. Furthermore, there are a large amount of reactive p-benzyl chloride groups on the tube surfaces, which are suitable for the synthesis of derivatives and the preparation of functional materials.

A new catalyst is reported for atom transfer radical polymerization (ATRP) for the synthesis of copper-free poly(2-diethylaminoethyl methacrylate (PDEAEM)-based pentablock copolymeric biomaterials that have been shown to be effective gene delivery vectors. Biocompatibility is an increasing concern with growing applications for functional polymers with potential applications in drug and gene delivery, because of the residual soluble copper salts used as catalysts. The reported ATRP synthesis method utilizes novel copper(I) oxide nanoparticles as catalysts that can be easily removed after polymerization, with X-ray spectroscopy (XPS) showing no residual copper in the final product.

A new catalyst for atom transfer radical polymerization (ATRP) for the synthesis of copper-free block copolymers is reported. Biocompatibility is an increasing concern with growing applications for polymers synthesized by ATRP in the fields of biology and medicine. The use of cuprous oxide nanoparticles as catalysts allows for the controlled synthesis of polymers with low toxicity with no residual copper.

A novel graft copolymer is synthesized from commercially available poly(vinyl alcohol) using ring-opening polymerization. For the polymerization reaction of novel brush-like poly(vinyl alcohol)-graft-poly(ϵ-caprolactone-co-(3-/7-(prop-2-ynyl)oxepan-2-one) 5 Sn(Oct)₂ is used as a catalyst. The formation of the graft copolymer is confirmed by ¹H NMR, ¹³C NMR, and Fourier transform infrared (FTIR) spectroscopy. Furthermore, the modification of the novel synthesized graft copolymer via a “click” reaction to implement adamantane groups is described. The success of the “click” reaction is proven by ¹H NMR spectroscopy and visualized by decomplexation of cyclodextrin with included phenolphthalein.

A novel brush-like graft copolymer with propyne groups is successfully synthesized by ring-opening polymerization of propargyl-modified lactone in the presence of poly(vinyl alcohol) as a macroinitiator. Adamantane moieties are attached by “click” reaction. The obtained graft copolymers contain adamantane moieties, which are a suitable guest for cyclodextrin, which is shown by phenolphthalein decomplexation from cyclodextrin.

A series of yttrium amido complexes bearing quadridentate binaphthyl-bridged Schiff-base salen-like and diamine bisphenolate salan-like ligands are synthesized and characterized. The complexes act as active initiators in the polymerization of rac-β-butyrolactone (rac-BBL) under mild conditions. The obtained poly(3-hydroxybutyrate) (PHBs) are syndiotactic enriched. ¹³C NMR spectroscopy microstructure analysis shows the probability of racemic linkages P_r to be up to 0.81. Statistical Bernoullian analysis evidences that a chain-end mechanism of steric control operates for the salan-like compound bearing cumyl substituents in the ortho position of the phenolate rings. The melting temperatures of the syndiotactic enriched PHBs are in the range 120–157 °C, depending on the degree of stereoregularity of the polymers.

New yttrium complexes bearing phenoxyamine salan-like and binaphthyl-bridged phenoxyimine salen-like ligands, having bulky substituents on the phenolate rings, are synthesized. They result active in the ring-opening polymerization of racemic β-butyrolactone, producing high molecular weight, syndiotactic-enriched poly(3-hydroxybutyrates). Polymers having probability of racemic linkages (P_r) up to 0.81 and melting point up to 157 °C are obtained in very mild conditions.

Novel (co)polyesters are synthesized from rapeseed-derived renewable starting materials. Aliphatic monomers are obtained from oleic and erucic acid via thiol-ene addition, whereas ferulic acid is used for the synthesis of aromatic monomers. Copolyesters with different ratios of these monomers are prepared via base-catalyzed transesterification reactions under neat conditions. Both monomer and polymer synthesis are optimized to achieve a high yield using environmentally benign synthetic procedures. A focus is put on applying less-toxic reagents (i.e., avoiding halogenated compounds) and on minimizing the produced waste, in order to meet the requirements of green chemistry. The resulting thioether-bearing (co)polyester series is analyzed, and finally oxidized to sulfone analogues. The thermal properties before and after oxidation are then compared.

Renewable aromatic and aliphatic monomers, all potentially rapeseed derived, are synthesized using environmentally benign conditions. Their copolymerization leads to a series of aromatic/aliphatic co-polyesters with adjustable thermal properties. In particular, the oxidation of sulfide groups to sulfones leads to pronounced changes of the thermal properties of these polymers.

New thiols for efficient thiol-ene polymerization reactions are presented. They do not exhibit any unpleasant odor, are characterized by quite good light-absorption properties at λ > 300 nm, and generate thiyl radicals upon UV-light exposure. Due to these interesting properties and contrary to many previously reported methodologies, the present thiol-acrylate polymerizations can be efficiently carried out without the presence of any additional photoinitiator. The chemical mechanisms are investigated by steady-state photolysis and electron spion resonance (ESR) experiments. Important parameters can also be extracted from molecular orbital calculations.

New thiols for efficient thiol-ene photopolymerization reactions are presented. They are characterized by quite good light-absorption properties and generate thiyl radicals upon UV-light exposure (i.e., the polymerizations can be carried out without the presence of any additional photoinitiator). These systems are also very efficient in overcoming oxygen inhibition.

Anisotropic shape-memory elastomeric composites (A-SMEC) are fabricated by infiltrating an aligned electrospun fibrous web with an elastomer, and curing. Mechanical testing proves strong anisotropy in Young's modulus (E_Y), strain-to-failure (ϵ_f), and yield stress (σ_y) observed with averages of E_Y = 48.4 and 4.0 MPa, ϵ_f = 198 and 351%, and σ_y = 4.6 and 0.9 MPa for longitudinal and transverse loading directions, with respect to the fibrous web's orientation. Shape-memory (SM) characterization reveals modest anisotropy in the shape fixing ratios (R_f), yet seemingly isotropic shape recovery (R_r) nearing completeness. Such soft, anisotropic materials may be used in laminated composite elastomers.

Anisotropic shape-memory elastomeric composites are prepared by electrospinning a web of oriented fibers, followed by the infiltration, and cure of a silicone matrix. The mechanical properties of the composites are found to be strongly anisotropic in a manner similar to bat wing membranes. Shape-memory testing reveals a dependence of the strain-fixing degree on the orientation direction, and excellent shape recovery in all directions.

Open porous foams with identical foam density but different pore-size distributions (bimodal or monomodal) are prepared from a shape-memory polyetherurethane (PEU) by thermally induced phase separation. The shape-memory effect of the two PEU foams is explored by cyclic thermomechanical compression tests and microstructural analysis. The obtained results reveal that the PEU foam with a bimodal pore-size distribution exhibits an increased shape-recovery under stress-free conditions, both on the macro- (foam level) as well as the microscale (pore level). While bimodal pore-size distributions induce microscale bending during compression, buckling occurs in foams with monomodal pore-size distributions, leading to both a reduced and delayed shape recovery.

The shape-memory effect of polymer foams is influenced by their morphology and density. Two shape-memory polymer foams are prepared by thermally induced phase separation with identical foam density but different pore-size distributions. While bimodal pore-size distributions induce microscale bending during compression, buckling occurs in foams with a monomodal pore-size distribution, leading to both a reduced and delayed shape recovery.

Non-natural amino acids can be used to expand the protein sequence space significantly beyond the limits set by nature. Expanding the protein sequence space opens a new door to engineering and chemically modifying proteins. Reassigning codons to non-natural amino acids as well as engineering protein translational machinery is required to incorporate non-natural amino acids into a single or multiple sites of a target protein in cells. Non-natural amino acid incorporation holds a great promise in substantially improving protein intrinsic properties and providing new orthogonal chemistries to proteins for bioconjugation.

Two distinct strategies, residue-specific and site-specific incorporation, allow biosynthesis of a protein containing non-natural amino acids. Non-natural amino acids introduced into a protein can be used to manipulate spectral and catalytic properties of a protein and provide new protein chemistries for bioconjugation with versatile molecules.

A novel polymeric gel is designed and synthesized, based on rotatable 1,1′,3,3′-tetrakis(4-aminophenyl)ferrocene cross-linking units capable of hinge-like motion. This hinge-linked gel results from an end-to-end reaction between the ferrocene-based cross-linker and a bifunctional poly(amide acid) oligomer. The cross-linking reaction efficiency is estimated by sol fraction analysis based on the Miller–Macosko model. Mechanical properties and rheological measurements show that the hinge-linked gel exhibits good mechanical stability and perfect elastic properties, although the gel cross-linking depends solely on metal–organic coordination at the ferrocenyl center. The hinge-linked network concept presented herein offers a novel design concept, which may be applicable to a variety of polymeric materials such as resins, metal–organic frameworks, and gels.

A new type of polymer network is designed and synthesized, based on rotatable ferrocene-type cross-links. The resulting polymeric gel exhibits good mechanical strength and elastic properties, even though cross-linking originates only from metal–organic coordination at the ferrocenyl centers.

A shape memory biodegradable polyurethane composite is prepared and shape recovery and simultaneous release of embedded copper sulfate are realized by high intensity focused ultrasound (HIFU). The composite shows an excellent HIFU-controlled shape recovery performance, wherein temporal and spatial control can be realized by switching the HIFU on/off or selecting the place where the ultrasound is focused. The composite shows an excellent HIFU switchable drug release function. The release process of a model payload can be tuned by adjusting the HIFU intensity and time. The shape memory polyurethane shows a rapid enzymatic biodegradation rate. This polyurethane composite has potential applications in minimally invasive interventional therapy devices.

A shape memory biodegradable polyurethane composite is prepared with polycaprolactone as the switching segment. The composite shows excellent high intensity focused ultrasound (HIFU) controlled shape recovery and drug release functions and a rapid enzymatic biodegradation rate, which has potential applications in minimally invasive interventional therapy devices.

The thermally induced shape-memory effect of polymers is typically characterized by cyclic uniaxial thermomechanical tests. Here, a molecular-dynamics (MD) simulation approach of such a cyclic uniaxial thermomechanical test is presented for amorphous switching domains of poly(L-lactide) (PLLA). Uniaxial deformation of the constructed PLLA models is simulated with a Parinello–Rahman scheme, as well as a pragmatic geometrical approach. We are able to describe two subsequent test cycles using the presented simulation approach. The obtained simulated shape-memory properties in both test cycles are similar and independent of the applied deformation protocols. The simulated PLLA shows high shape fixity ratios (R_f ≥ 94%), but only a moderate shape recovery ratio is obtained (R_r ≥ 30%). Finally, the structural changes during the simulated test are characterized by analysis of the changes in the dihedral angle distributions.

The thermally induced shape-memory effect (SME) of polymers can be quantified in cyclic, thermomechanical tensile tests. Here, a method for simulating such a cyclic thermomechanical test is introduced based on molecular-dynamics calculations, which focus on the behavior of the amorphous switching domains. Two subsequent test cycles can be described successfully for the SME of poly(L-lactide).

Novel electron beam crosslinked polyurethane shape memory polymers with advanced processing capabilities and tunable thermomechanical properties have been synthesized and characterized. We demonstrate the ability to manipulate crosslink density in order to finely tune rubbery modulus, strain capacity, ultimate tensile strength, recovery stress, and glass transition temperature. This objective is accomplished for the first time in a low-molecular-weight polymer system through the precise engineering of thermoplastic resin precursors suitable for mass thermoplastic processing. Neurovascular stent prototypes were fabricated by dip-coating and laser machining to demonstrate processability.

A thermoset polyurethane shape memory polymer exhibiting novel processing capabilities and tunable material properties is reported. This SMP can be processed into complex geometries as a thermoplastic and crosslinked to desired extents using electron beam irradiation. The neurovascular stent prototype fabricated in this work demonstrates the SMP's novel processing capability.

SMPs have been shown to actuate below their dry glass transition temperatures in the presence of moisture due to plasticization. This behavior has been proposed as a self-actuating mechanism of SMPs in water/physiological media. However, control over the SMP actuation rate, a critical factor for in vivo transcatheter device delivery applications, has not been previously reported. Here, a series of polyurethane SMPs with systematically varied hydrophobicity is described that permits control of the time for their complete shape recovery in water from under 2 min to more than 24 h. This control over the SMP actuation rate can potentially provide significant improvement in their delivery under conditions, which may expose them to high-moisture environments prior to actuation.

A controlled rate of actuation of ultralow-density shape-memory polymer foams in water is reported. The time of complete shape recovery is controlled from 2 min to >24 h based on material composition. This ability to control the actuation rate may significantly improve the delivery of SMP medical devices under conditions that require exposure to high-humidity environments prior to actuation.

Recently, we have reported that azobenzene-functionalized polyimide materials exhibit a substantial increase in photogenerated stress in comparison to azobenzene-functionalized acrylate-based liquid crystal polymer networks. Here, we show that pre-straining the azo-CP2-20 material further increases the magnitude of the photomechanical response visualized as bending in the cantilever geometry as well as in direct measurements of photogenerated stress. Additionally, we also report on the ability to optically fix both optically and mechanically generated shapes in azo-CP2-20. The optically fixable shape memory of azo-CP2-20 is enabled by the introduction of excess free volume during thermal processing as the material was pre-strained.

The photomechanical output of glassy, crosslinked azobenzene-functionalized polyimide is examined both in a cantilever and tensile geometry. The magnitude of photogenerated stress output is doubled by “pre-straining” a glassy, azobenzene-functionalized polyimide. Subjecting the material to thermal processing allows the material to exhibit shape memory behavior.

The study investigates the scope for significant enhancements in shape-memory properties in blends of thermoplastic polyurethanes (PUs) and polybenzoxazine (PB). PB was expected to serve as a second fixed phase in addition to hard segment of PU. The shape-memory compounds were prepared in three steps. First, benzoxazine monomer was dissolved in urethane prepolymer synthesized from 4,4′-methylenebis (phenyl isocyanate) (MDI) and poly (tetramethylene) glycol (PTMG). Second, the prepolymer was chain extended with 1,4-butanediol (BD) without curing of benzoxazine. Third, the benzoxazine was polymerized into PB by thermal curing at 180 °C for 3 h. A compound with 17 wt% PB exhibited a recovery stress (RS) of 13 MPa and strain recovery (SR) of 93% compared with RS of 6.8 MPa and SR of 72% for PU.

Shape-memory polyurethane (SMPU)–polybenzoxazine (PB) compounds form interesting morphology and provide close to 100% increase in recovery stress and close to 100% recovery of shape.

Investigation of self-folding thin films, which mimic natural mechanisms of movement and form complex 3D structures, is a novel and very promising research direction. This manuscript summarizes recent advances in the development and application of biomimetic self-folding polymer films.

Recent advances in the development and application of biomimetic self-folding polymer films, which mimic natural mechanisms of movement and form complex 3D structures, are discussed in this manuscript.

Shape memory polymers (SMPs) based on blends of fatty acid or fatty acid salts and an elastomeric ionomer, sulfonated poly{ethylene-r-propylene-r-(5-ethylidene-2-norbornene)} are described. The permanent network is formed by nanophase separation of intermolecularly associated metal sulfonate groups, and the temporary network is developed by dispersed fatty acid crystals with strong dipolar interactions with the ionomer. The permanent network, however, creeps under load. SMPs with fixing efficiencies >95% and shape recovery efficiency of ≈100% were achieved by covalently crosslinking the ionomer.

Shape-memory polymers composed of fatty acid crystals dispersed in an elastomeric ionomer exhibit creep when loaded. The replacement of the ionic network, which provides the permanent crosslinks in the ionomer, with a covalent network eliminate the creep and produce SMPs with fixing efficiency of more than 95% and shape recovery efficiency of ≈100%.

Front Cover: Wheat gluten and the silica precursor tetraethoxylane are successfully assembled by a soft chemistry approach for the preparation of new hybrid materials. The acid-catalyzed in situ polymerization of silica in the presence of wheat gluten generates an interpenetrating 3D network with unprecedented physicochemical properties of the final materials. Further details can be found in the article by H. Türe, T. O. J. Blomfeldt, M. Gällstedt, M. S. Hedenqvist, and S. Farris* on page 1131.

Introducing well-defined polymeric side chains to bisterpyridine coordination polymers enables the synthesis of materials with tailor-made optical and mechanical properties. The polymers are introduced either by a copper-catalyzed azide–alkyne cycloaddition (grafting-onto) or an atom transfer radical polymerization (polymerization-from) method. The resulting metallopolymers exhibit improved solubility in common organic solvents and can, therefore, be inkjet-printed from chlorinated benzene solutions. The photophysical properties of the so-produced homogeneous films are investigated and a proof-of-principle polymer light-emitting device can be constructed.

Tailoring of the optical and mechanical properties of bisterpyridine coordination polymers is enabled by the introduction of well-defined polymeric side chains. The resulting metallopolymers exhibit improved solubility and processability and can, therefore, easily be inkjet-printed. The photophysical properties of the so-produced homogeneous films are investigated and a proof-of-principle polymer light-emitting device can be constructed.

A new two-dimensional-conjugated polymer (PBDTT3-TPA) containing benzodithiophene (BDT) and a side chain isolation comonomer is designed and synthesized. Interestingly, PBDTT3-TPA is compatible with higher lowest unoccupied molecular level (LUMO) acceptors of indene-C₆₀ bisadduct (ICBA), and polymer solar cells based on PBDTT3-TPA/ICBA show an open-circuit voltage (V_OC) of ca. 0.80 V and a power conversion efficiency of 2.48% under AM1.5G illumination of at 100 mW cm⁻². Furthermore, the energy loss in the corresponding fullerene acceptor devices is discussed, and the increase in the observed V_OC is explained quantitatively by the up-shifted LUMO energy of ICBA (0.17 eV) and the reduced saturation current (J_SO) in the blends.

A new copolymer is designed and synthesized, and the photovoltaic performance is optimized with fullerene acceptors. The energy loss and the increase in the observed open-circuit voltages are quantitatively explained by the up-shifted lowest unoccupied molecular level of indene-C₆₀ bisadduct (ICBA) and the reduced saturation current in the blends.

A liquid crystal (LC) ABA triblock copolymer with poly(styrene) (PS) A blocks and a main-chain nematic LC polyester B block is synthesized by atom-transfer radical polymerization of styrene with an LC polyester macro-initiator. The nematic LC and PS amorphous phases are segregated from each other to form lamellae with a spacing of 27 nm. The 16 nm-thick nematic LC lamellae are significantly smaller than the contour length of the LC segment (63 nm), and the nematic director is parallel to the lamellae. The central LC segment is primarily more extended in the lamellar direction, but folds so as to meander through the LC lamella and bridges adjacent PS domains. The lamellar microstructure exhibits a reversible spacing increase of up to 31 nm with increasing temperature, suggesting a corresponding increase in the probability of the chain folding.

An ABA triblock copolymer that is composed of poly(styrene) (PS) A blocks and a main-chain nematic liquid crystal (LC) B block forms a lamellar morphology with a 27 nm spacing. The LC blocks, 63 nm contour length, are primarily more extended in the lamellar direction and meander through the LC lamella to bridge the PS domains.

The synthesis of polystyrene (PS) brushes on fully deuterated PS nanoparticles by surface-initiated nitroxide-mediated radical polymerization (SI-NMRP) is reported. Due to the high demand of deuterated monomers, an efficient deuteration procedure of suitable and readily available precursors is developed. SI-NMRP of styrene is improved regarding reaction control, grafting density, and conversion. Insights into the scaling behavior and conformational features of surface-attached PS chains on deuterated particles are investigated by using dynamic light scattering measurements, proving that polymer brushes are formed. The particles with surface-attached initiator are shown to be uniform spherical core-shell particles by small-angle neutron scattering measurements.

Fully deuterated polystyrene (PS) core particles are synthesized by emulsion polymerization and modified with a functional shell for surface-initiated nitroxide-mediated radical polymerization (SI-NMRP) of styrene. A convenient synthetic protocol is given to obtain the deuterated monomers, styrene-d₈ and divinylbenzene-d₁₀, with a high degree of deuteration (>96%). Polymerization conditions are optimized leading to defined PS polymer brushes on deuterated particles.

Typically, intramolecular cyclization reactions need to be conducted at high dilution to avoid interchain coupling, which leads to the production of cyclic polymer at an extremely low output. Herein, a high-efficiency Cu-catalyzed azide/alkyne cycloaddition “click” synthesis of cyclic polystyrene (PS) and cyclic poly (methyl methacrylate) (PMMA) is reported via a circulatory technique of evaporation–condensation–extraction–inflow strategy by the utilization of elaborately designed equipment. High-output cyclic PS (one batch, 0.71 g cyclic polymer from 1.0 g linear polymer loading) and cyclic PMMA (one batch, 0.62 g cyclic PMMA from 1.0 g linear polymer loading) are achieved. This promising preparation should be beneficial to the large-scale application and research of cyclic polymers.

A high-efficiency Cu-catalyzed azide/alkyne cycloaddition “click” synthesis of cyclic polystyrene (PS) and cyclic poly (methyl methacrylate) (PMMA) via a circulatory technique of evaporation–condensation–extraction–inflow strategy is reported. High-output cyclic PS and cyclic PMMA are efficiently achieved. This promising preparation should be beneficial to the potential large-scale application and research of cyclic polymers.

This paper focuses on two different strategies to incorporate gold nanoparticles (AuNPs) into the matrix of polyacrylamide (PAAm) hydrogels. Poly(ethyleneimine) (PEI) is used as both reducing and stabilizing agent for the formation of AuNPs. In addition, the influence of an ionic liquid (IL) (i.e., 1-ethyl-3-methylimidazolium ethylsulfate) on the stability of the nanoparticles and their immobilization in the hydrogel is investigated The results show that AuNPs surrounded by a shell containing PEI and IL, synthesized according to the “one-pot” approach, are much better immobilized within the PAAm hydrogel. Hereby, the IL is responsible for structural changes in the hydrogel as well as the improved stabilization and embedding of the AuNPs into the polymer gel matrix.

Gold nanoparticles (AuNPs) surrounded by a shell containing poly(ethyleneimine) and ionic liquid (IL) are formed in situ in a poly(acrylamide) hydrogel matrix. Conductometric measurements show that the core–shell AuNPs formed in a “one-pot” synthesis are much better immobilized due to additional hydrogen bonding between the IL and the hydrogel matrix.

A benzoxazine-bridged bis(triethoxysilane) (BFS) compound is synthesized by a condensation reaction and characterized. Different ratios of BFS are integrated into 6,6-(1-methylethyliden)-bis-(3,4-dihydro-3-phenyl-2H-1,3-benzoxaizne) (Ba) through solution mixing; thermally hybrid-cured polymers are obtained. The neat, cured polymers (PBFS100) based on BFS display low water absorption, low dielectric constant, and a glass-transition temperature (T_g) of 169 °C. The thermal properties, water absorption, and dielectric properties of the hybrid polymers are markedly improved due to the incorporation of BFS. Electron microscopy observation reveals that the polymer hybrid features a self-assembled lamellar structure responsible for the enhanced properties of polybenzoxazine/silsesquioxane composites.

A polybenzoxazine-bridged polysilsesquioxane material based on BFS and Ba is prepared and characterized. Due to the lamellar structure, and the low polarity of fluorenyl and silsesquioxane, the cured materials exhibit a low dielectric constant and water absorption. Furthermore, the glass-transition temperature of the cured polymer, based on Ba, is markedly improved by modifying with BFS.

The main physicochemical properties of nanostructured silica/wheat gluten hybrid composites are presented. The extraction experiments suggest that the protein phase is intimately encased within the silica matrix, with silica–protein interactions driven by hydrogen bonding, as indicated by IR spectra. Spectroscopic results also show that silica induces a higher degree of constraint of the wheat gluten matrix, despite less aggregation. Moisture diffusion properties of the hybrid materials are investigated by a combined “desorption/sorption” approach. While the reduction of the moisture diffusivity in the presence of silica can be described by the geometrical impedance of a “sintered” porous solid, a time-dependent relaxation/restructuring of the composite apparently occurs during the sorption-desorption cycle.

An integrated physicochemical approach is used to produce silica/wheat gluten hybrid composites through sol–gel chemistry. Silica constrains the organic network, leading to enhanced thermal properties, whereas the constraint does not affect the moisture-diffusion properties of the hybrid network. The reduced moisture diffusivity of the hybrid materials is explained in terms of geometric impedance.

Aqueous-phase free-radical batch polymerizations of N-vinylimidazole (NVI) and quaternized N-vinylimidazole (QVI) are conducted with varying initial monomer and initiator concentrations at 70 and 85 °C. The polymerization rate of NVI is very slow at the natural pH of 9 due to degradative radical addition to monomer. The rates are increased by lowering the pH, wherein the degradative addition to NVI monomer is partially (at pH 4) and completely (at pH 1) hindered, with the polymerization rate matching that of QVI at pH 1. The initial rates of polymerization for both NVI and QVI are independent of temperature. A kinetic model developed in Predici that includes the pH-dependent side reactions can reasonably represent both QVI and NVI polymerization.

The polymerization rate of N-vinylimidazole in aqueous solution is a strong function of pH due to degradative addition to monomer. At a pH of 1, the rate is identical to that of quaternized N-vinyl imidazole. The observed experimental polymerization behavior is well represented over a range of operating conditions by a simple model accounting for the side reactions.

Six conjugated polymers based on the indenopyrazine (IPY) unit are designed and synthesized by copolymerization with different electron-deficient and electron-rich building blocks. All of the polymers show good solubility, excellent film-forming ability, and low-lying highest occupied molecular orbit (HOMO) energy levels. The effects of the different copolymerized units on the optical, electrochemical, and photovoltaic properties are investigated. Results indicate that their bandgaps and molecular energy levels are readily tuned by copolymerizing with electron-deficient and electron-rich units. Polymer solar-cell devices are fabricated utilizing the polymers as electron donors and [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) as an electron acceptor. The best power conversion efficiency of the cell based on PIPY-DTBTA, one of the IPY- based polymers, reaches 0.77%, with a relatively high V_oc up to 0.78 V.

Six conjugated polymers based on the indenopyrazine unit are synthesized by copolymerization with different electron-deficient and electron-rich blocks. The effects of the different copolymerized units on the optoelectronic and photovoltaic properties of the polymers are investigated. The results indicate that the bandgaps and energy levels are readily tuned by different copolymerizing units, which can provide a guideline for the design of photovoltaic materials.

Nanoprecipitation of poly(methyl methacrylate) (PMMA) in the presence of water-soluble core cross-linked star (CCS) polymers is investigated. Slowly dropping water into DMF solutions containing PMMA and CCS polymers of varying compositions produces colloidally stable particles with CCS polymers being effectively incorporated. During the solvent-shifting process, CCS polymers migrate to and concentrate at the particle surface to stabilize the formed particles, which is confirmed by X-ray photoelectron spectroscopy, transmission electron microscopy, and contact angle measurements. This stabilizing effect is realized via the steric effect of the CCS polymers adsorbed at the particle surface.

Core cross-linked star (CCS) polymers can be used to stabilize nanoprecipitation of poly(methyl methacrylate). CCS polymers migrate to and concentrate at the particle surface to stabilize the particles produced by nanoprecipitation sterically, representing a new mechanism of conferring colloidal stability.