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Perovskite solar cells (PSCs) with excellent photoelectric properties have attracted much attention in recent years. However, the solution manufacturing of PSCs inevitably introduces a large number of defects (both bulk and surface defects), which seriously affect the performance of PSCs. Defect passivation from additive engineering is an effective and simple strategy. Among these additives, polymers are increasingly attracting attention due to their excellent properties, such as adjustable structures, multiple functional groups, excellent stability, and low cost, which can further promote the commercialization of PSC technology. However, the application of polymers in PSCs have encountered some obstacles due to a lack of systematic studies, such as unelucidated interactions between polymers and perovskites, the frequent trial‐and‐error process used in material selection, and the lack of effective guidelines. In this review, the application of polymers in various layers of PSCs devices is first summarized. Then, three main roles of polymers in PSCs are summarized, including crystallization regulation, the mechanical stability enhancement of flexible perovskite solar cells (FPSCs), and their use as undoped hole transport materials (HTMs). More importantly, machine learning (ML) is proposed to design and select polymers as passivators and HTMs for PSCs. Finally, promising guidelines and recommendations are provided for the commercialization of PSCs. [ABSTRACT FROM AUTHOR]

This work reports on the synthesis of statistical copolymers of bio‐based PA 6.19 and PA 6.6 together with the production of melt‐spun monofilaments for the production of sustainable textile fibers. The plant oil‐based 1.19‐nonadecanedioic acid is synthesized from bio‐derived oleic acid via isomerizing methoxycarbonylation. The homopolymer PA 6.19 with a carbon‐based bio‐content of 72% shows a good elongation at break of 166%, but lower tensile strength than commercial PA 6 (43 MPa versus 82 MPa). Addition of adipic acid to form statistical PA 6.6/6.19 copolymers improves toughness while maintaining the high elongation at break. Two PA 6.6/6.19 copolymers with a carbon‐based bio‐content of 26% and 33% are successfully synthesized and exhibited comparable toughness (94 ± 6 MPa and 92 ± 2 MPa) to the commercial PA 6 (92 ± 15 MPa). The bio‐based copolymers also exhibit a much lower water uptake than PA 6 and PA 6.6, resulting in a higher dimensional stability. Melt spinning of the oleic acid‐based polyamides is successfully carried out to produce monofilaments with sufficient properties for further processing in a knitting process, demonstrating the capabilities of the bio‐based PA 6.6/6.19 copolymers for use in the textile industry. [ABSTRACT FROM AUTHOR]

[Display omitted] Chromium (Cr)-containing wastewater has caused a serious threat to the environment due to its high toxicity and mobility. The traditional Cr removal methods are generally based on an inconvenient two-step process with the first transformation of Cr(VI) to Cr(III) and the consecutive removal of Cr(III) by precipitation. Herein, we demonstrate the efficient all-in-one removal of total Cr through the simultaneous photocatalytic reduction of Cr(VI) to Cr(III) and in-situ fixation of Cr(III) over the nonconjugated polymer engineered ZnIn 2 S 4 (P-ZIS) photocatalyst. By in-situ polyvinylpyrrolidone (PVP) modification of ZIS during the preparation process, the resulted P-ZIS can completely reduce Cr(VI) within 60 min under visible light irradiation. The kinetics of Cr(VI) reduction over P-ZIS is 2.8 times as that of pure ZIS, which is proved to be benefited from the enhanced light absorption, uplifted conduction band for strengthening reducibility, and accelerated charge carrier transfer. Moreover, as compared to ZIS, P-ZIS also exhibits significantly improved in-situ adsorption ability for Cr(III), thus resulting in efficient all-in-one elimination of total Cr within a single system. We show that this polymer engineered strategy could be a facile and versatile protocol for modulating the electronic structure and surface chemistry of the semiconductor photocatalysts towards complete, safe, and cost-efficient removal of Cr. [ABSTRACT FROM AUTHOR]

Poly-γ-glutamic acid (γ-PGA) is a bio-derived water-soluble, edible, non-immunogenic nylon-like polymer with the biochemical characteristics of a polypeptide. This Bacillus-derived material has great potential for a wide range of applications, from bioremediation to tunable drug delivery systems. In the context of oral care, γ-PGA holds great promise in enamel demineralisation prevention. The salivary protein statherin has previously been shown to protect tooth enamel from acid dissolution and act as a reservoir for free calcium ions within oral cavities. Its superb enamel-binding capacity is attributed to the L-glutamic acid residues of this 5380 Da protein. In this study, γ-PGA was successfully synthesised from Bacillus subtilis natto cultivated on supplemented algae media and standard commercial media. The polymers obtained were tested for their potential to inhibit demineralisation of hydroxyapatite (HAp) when exposed to caries simulating acidic conditions. Formulations presenting 0.1, 0.25, 0.5, 0.75, 1, 2, 3 and 4% (w/v) γ-PGA concentration were assessed to determine the optimal conditions. Our data suggests that both the concentration and the molar mass of the γ-PGA were significant in enamel protection (p = 0.028 and p < 0.01 respectively). Ion Selective Electrode, combined with Fourier Transform Infra-Red studies, were employed to quantify enamel protection capacity of γ-PGA. All concentrations tested showed an inhibitory effect on the dissolution rate of calcium ions from hydroxyapatite, with 1% (wt) and 2% (wt) concentrations being the most effective. The impact of the average molar mass (M) on enamel dissolution was also investigated by employing commercial 66 kDa, 166 kDa, 440 kDa and 520 kDa γ-PGA fractions. All γ-PGA solutions adhered to the surface of HAp with evidence that this remained after 60 min of continuous acidic challenge. Inductively Coupled Plasma analysis showed a significant abundance of calcium ions associated with γ-PGA, which suggests that this material could also act as a responsive calcium delivery system. We have concluded that all γ-PGA samples tested (commercial and algae derived) display enamel protection capacity regardless of their concentration or average molar mass. However, we believe that γ-PGA D/L ratios might affect the binding more than its molar mass. [ABSTRACT FROM AUTHOR]

[Display omitted] • PVP mitigates the effect of moisture on electrospun CH 3 NH 3 PbCl 3 perovskite film. • Lattice constants, crystallite and particle size is reduced in PVP capped film. • PVP improves morphology and reduces oxygen content of film compared to pure one. • CH 3 NH 3 PbCl 3 is used as ETL layer in a planner structured perovskite solar cell. • The cell exhibits PCE of 21.65% with FF = 72.21%, J sc = 32.44 mA/cm2, V oc = 0.924 V. Due to the inherent moisture instability problem of hybrid lead halide perovskites, polymer additives have to turn out to be a significant research area to enhance the moisture stability of these materials. It has been found that polymer engineering on the absorber layer of solar cells significantly improves chemical stability and overall device performance. This work reports the fabrication of pristine and polyvinylpyrrolidone (PVP) polymer capped methylammonium lead chloride (CH 3 NH 3 PbCl 3) perovskite film via the electrospinning method. A structural study using an X-ray diffractometer shows a sharp fall in average crystallite size from 66.05 nm to 39.69 nm when PVP is used in the synthesis procedure. A similar trend is also seen in the microscopic analysis, which depicts that the particle size has decreased for PVP added CH 3 NH 3 PbCl 3 perovskite film in comparison to CH 3 NH 3 PbCl 3 pristine film. The surface coverage and uniformity of the film is much more in the presence of PVP. It has been noted from energy dispersive X-ray analysis that the oxygen content is ∼16% more in the pure film, i.e. PVP hinders the effect of moisture in perovskite film, which is the prime objective of this work. Moreover, the optical properties have been analyzed using diffuse reflectance mode of UV–Vis-NIR spectroscope. Finally, the use of CH 3 NH 3 PbCl 3 as the electron transport layer has been demonstrated in Glass/FTO/CH 3 NH 3 PbCl 3 /CH 3 NH 3 SnI 3 /Spiro-OMeTAD/Au structured perovskite solar cell using the SCAPS-1D simulator. The above-mentioned cell exhibits a power conversion efficiency (PCE) of 21.65%, fill factor (FF) of 72.21%, 32.44 mA/cm2 of short circuit current density (J sc), and 0.924 V open-circuit voltage (V oc). [ABSTRACT FROM AUTHOR]

Reversible covalent polymers are able to change their bond arrangement and structure via reversible reaction triggered by external stimuli including heating, light and pH, while retaining the stability of irreversible covalent polymers in the absence of the stimuli. In recent years, more and more research has been devoted to utilization of reversible covalent bonds in synthesizing new materials, which not only overcomes disadvantages of permanent covalent polymers, but also brings in new functionalities. More importantly, a series of novel techniques dedicated to polymerized products with features such as properties regulation, self-healing, reprocessing, solid state recycling, and controllable degradation are developed, heralding the opportunity of upgrading of traditional polymer engineering. Although the exploration of this emerging topic is still in its infancy, the advances so far are encouraging and clearly directed to large scale applications. This review systematically outlines this promising trend, following a bottom-up strategy, taking into account both theoretical and experimental achievements. It mainly consists of four parts, involving design and preparation: (i) the basis of reversible covalent chemistry, (ii) rheology of reversible covalent polymers, (iii) methods of construction of reversible covalent polymers, and (iv) smart, adaptive properties offered by reversible covalent chemistry. The key elements for realizing reorganization of polymers containing reversible covalent bonds are covered. The advantages and weaknesses of representative reaction systems are analyzed, while the challenges and opportunities to engineering application of the equilibrium control based on reversible covalent chemistry for producing end-use polymers are summarized. In this way, the readers may grasp both the overall situation as well as insight into future work. [ABSTRACT FROM AUTHOR]

DNA damaging chemotherapy is a cornerstone of current front-line treatments for advanced ovarian cancer (OC). Despite the fact that a majority of these patients initially respond to therapy, most will relapse with chemo-resistant disease; therefore, adjuvant treatments that synergize with DNA-damaging chemotherapy could improve treatment outcomes and survival in patients with this deadly disease. Here, we report the development of a nanoscale peptide-nucleic acid complex that facilitates tumor-specific RNA interference therapy to chemosensitize advanced ovarian tumors to frontline platinum/taxane therapy. We found that the nanoplex-mediated silencing of the protein kinase, MK2, profoundly sensitized mouse models of high-grade serous OC to cytotoxic chemotherapy by blocking p38/MK2-dependent cell cycle checkpoint maintenance. Combined RNAi therapy improved overall survival by 37% compared with platinum/taxane chemotherapy alone and decreased metastatic spread to the lungs without observable toxic side effects. These findings suggest (a) that peptide nanoplexes can serve as safe and effective delivery vectors for siRNA and (b) that combined inhibition of MK2 could improve treatment outcomes in patients currently receiving frontline chemotherapy for advanced OC. [ABSTRACT FROM AUTHOR]

Polymeric drug delivery devices are among the most promising avenues to improve the equitable distribution of life-saving medications throughout the world. At present, most research into manufacturing these devices relies heavily on solvent-based methods, limiting scalability, reproducible manufacture, and potentially leading to cytotoxicity. Solvent-free polymeric biomedical implants manufactured through traditional thermal processing methods eliminate the bulk of these concerns. However, they are difficult to manufacture in a research laboratory setting. Investigation of manufacturing techniques such as injection molding has been limited in the past due to the high upfront cost of polymer equipment and the large scale necessary to conduct pilot experiments. This study describes a low-cost bench-top milliliter-volume vacuum injection-molding system capable of pilot-scale injection molding of small shapes of arbitrary geometry. The plans presented herein open this convenient and scalable manufacturing technique to academic research laboratories interested in pilot-scale experiments with polymeric devices. Polymers relevant for polymeric drug or vaccine delivery are investigated, and a demonstration of the fabrication of simple geometric parts and solvent-free polymeric microneedle patches is described. In particular, microneedle patches demonstrate the capabilities and limitations of producing fine feature sizes for biomedically relevant products. [Display omitted] • Assembly of a gram-scale injection molding system with 3D printed inserts. • Melt processing of polymers at high temperature and pressure. • Demonstration of dissolvable solvent-free injection molded microneedle patches. • Method for the fabrication of microneedle injection molds. • Facile production of 3D printed mold inserts for rapid swap and production of arbitrary shapes. [ABSTRACT FROM AUTHOR]

Microfluidics is the art of creating and manipulating small portions of fluids. A typical variant of this art is fluid transport within small channels, either in form of laminar co-flow of miscible streams or in form of segmented-flow dripping and jetting of immiscible streams. Either method provides means to expose components of interest to defined local conditions such as spatially controlled concentration profiles that could not be established without the microfluidic auxiliaries. This ability renders microfluidics uniquely useful as both a method for advanced analytics and synthesis. This article sheds a spotlight on the use and utility of this method in macromolecular chemistry and physics. In this field, the synthetic aspect of microfluidics has been widely explored in macromolecular materials engineering, primarily by the use of droplets as templates to form various types of polymeric particles and capsules, whereas the analytical aspect has most prominently been employed for research on biopolymers. [ABSTRACT FROM AUTHOR]

Layer-by-layer (LbL) based self-assembly of nanoparticles is an emerging and powerful method to develop multifunctional and tissue responsive nanomedicines for a broad range of diseases. This unique assembly technique is able to confer a high degree of modularity, versatility, and compositional heterogeneity to nanoparticles via the sequential deposition of alternately charged polyelectrolytes onto a colloidal template. LbL assembly can provide added functionality by directly incorporating a range of functional materials within the multilayers including nucleic acids, synthetic polymers, polypeptides, polysaccharides, and functional proteins. These materials can be used to generate hierarchically complex, heterogeneous thin films on an extensive range of both traditional and novel nanoscale colloidal templates, providing the opportunity to engineer highly precise systems capable of performing the numerous tasks required for systemic drug delivery. In this review, we will discuss the recent advancements towards the development of LbL nanoparticles for drug delivery and diagnostic applications, with a special emphasis on the incorporation of biostability, active targeting, desirable drug release kinetics, and combination therapies into LbL nanomaterials. In addition to these topics, we will touch upon the next steps for the translation of these systems towards the clinic. [ABSTRACT FROM AUTHOR]

Layer-by-layer (LbL) self-assembly is a versatile technique from which multi­component and stimuli-responsive nanoscale drug-carriers can be constructed. Despite the benefits of LbL assembly, the conventional synthetic approach for fabricating LbL nanoparticles requires numerous purification steps that limit scale, yield, efficiency, and potential for clinical translation. In this report, a generalizable method for increasing throughput with LbL assembly is described by using highly scalable, closed-loop diafiltration to manage intermediate purification steps. This method facilitates highly controlled fabrication of diverse nanoscale LbL formulations smaller than 150 nm composed from solid-polymer, mesoporous silica, and liposomal vesicles. The technique allows for the deposition of a broad range of polyelectrolytes that included native polysaccharides, linear polypeptides, and synthetic polymers. The cytotoxicity, shelf life, and long-term storage of LbL nanoparticles produced using this approach are explored. It is found that LbL coated systems can be reliably and rapidly produced: specifically, LbL-modified liposomes could be lyophilized, stored at room temperature, and reconstituted without compromising drug encapsulation or particle stability, thereby facilitating large scale applications. Overall, this report describes an accessible approach that significantly improves the throughput of nanoscale LbL drug-carriers that show low toxicity and are amenable to clinically relevant storage conditions. [ABSTRACT FROM AUTHOR]

Hydrogels that can form spontaneously via covalent bond formation upon injection in vivo have recently attracted significant attention for their potential to address a variety of biomedical challenges. This review discusses the design rules for the effective engineering of such materials, and the major chemistries used to form injectable, in situ gelling hydrogels in the context of these design guidelines are outlined (with examples). Directions for future research in the area are addressed, noting the outstanding challenges associated with the use of this class of hydrogels in vivo. [ABSTRACT FROM AUTHOR]

Thermo-analytical methods are widely used in the characterization of various materials. Among them, DSC is especially important for polymer analysis, since it enables determination of basic thermodynamic and kinetic parameters of crystallization, melting, crosslinking, etc. In this study we report the results of a rapid method used for the evaluation of the data obtained by DSC measurements of a cure reaction for thermosetting resins. The method was based on the Borchardt and Daniels kinetic model and enables determination of basic parameters that are important for product and process development, as well as for optimization of cure cycles for a variety of thermosets. The method described in this work will help university students and engineers in the fields of polymer science and engineering to simplify the analysis process for data collected during cure measurements with DSC. [ABSTRACT FROM AUTHOR]

Abstract: Polymers with high glass transition temperatures, fluorinated ethylene propylene copolymer (FEP) and poly(ethylene naphthalate) (PEN), have been used in imprint lithography as a protective support layer and as a secondary mould, to imprint superficial structures into a polymer with a lower glass transition temperature, namely poly(methyl methacrylate) (PMMA). As a support layer, FEP replaces fragile silicon based supports for the production of freestanding, structured sheets of PMMA, useful, for example, in biomedical applications where transmittance optical microscopy is required. Secondary PEN moulds, produced by imprinting using silicon-based primary moulds, have been used to transfer sub-micrometer tall structures to a freestanding PMMA sheet. Similarly, hole structures, with different dimensions, have been embossed in both sides of a PMMA sheet simultaneously. [Copyright &y& Elsevier]

Abstract: A novel process for the deposition of four different patternable polymers to be used as sensing layers in chemical sensors, on the same substrate, using lithographic techniques is described. The process is combined with the engineering of the swelling properties of two of the polymeric materials upon exposure to DUV irradiation to expand the array to six or eight elements. The use of lithographic processes allows the deposition of polymeric films at the desired pattern and for a wide film thickness range. The sensing properties of the deposited and engineered films in the array were characterized by monitoring volume expansion upon exposure to volatile organic compounds. The process is particularly useful in the fabrication of chemical sensor arrays where polymers with varying sensitivities and selectivities are required. [Copyright &y& Elsevier]

Any two polymer molecules of the same length (n) and the same number of branch points (N) can have different properties, since they may possess distinct architectures. In this paper we present conditional Monte Carlo algorithms for the virtual synthesis of polyethylene (PE) catalyzed by one branch forming constrained geometry metallocene catalyst (CGC, 1C-system) or by a mixture of CGC and linear metallocene catalyst (2C-system) in a continuous stirred tank reactor. The condition for the Monte Carlo method consists of a fixed chain length distribution and degree of branching distribution. To calculate these distributions explicit algebraic relations are available Macromolecules 36 (2003) 10037. The synthesis method is a recursive algorithm that subsequently creates insertions of sub-structures containing numbers of monomer units and branch points according to one- or two-dimensional probability density functions. We developed a general 2C-algorithm and a simplified 1C-algorithm applicable for 1C-systems only. They provide an adjacency matrix describing the connectivity between the branch points, while separately (1C-method Macromol Theor Simul 12 (2003) 484) or simultaneously (2C-method) a vector containing the length of segments between branch points and terminal segments is generated Macromol Theor Simul 10 (2001) 855. Characterization of the architectures proceeds by calculating the topological variables seniority and priority as well as the radius of gyration Macromol Theor Simul 10 (2001) 870. As regards seniority and priority good agreement is found with results from the analytical approach Macromolecules 36 (2003) 10037 is found. 2C-architectures turn out to possess more comb-like structures than 1C-architectures. Concerning molecular sizes an interesting effect of the segment length distribution in 2C-molecules is observed. [Copyright &y& Elsevier]

Polyetherimide (PEI) gas separation membranes were tailored, at the molecular scale, by the incorporation of nanostructured metallic complexes into the PEI network. The influence of these additives on the micropore size distributions of the membranes produced and on their performance for oxygen/nitrogen separation was investigated. Changing the metal within the same ligand had a significant influence on the microporosity and gas separation performance of these membranes. Magnesium (II) phathalocyanine (MgPc) in PEI membranes was found to be an excellent additive to increase membrane performance for air separation. The performance of these membranes increases with increasing additive concentrations. Membranes with this additive also exhibit an improved stability as determined through the annealing process. Annealing these membranes caused a slight decrease in their gas permeance and total micropore volume but a significant increase in their gas selectivity. The results show that the properties of the nanophase additive and nanophase-polymer interactions play a pivotal role in stabilizing and determining membrane performance for air separation. [Copyright &y& Elsevier]

Humic substances readily identifiable in the environment are involved in several biotic and abiotic reactions affecting carbon turnover, soil fertility, plant nutrition and stimulation, xenobiotic transformation and microbial respiration. Inspired by natural roles of humic substances, several applications of these substances, including crop stimulants, redox mediators, anti-oxidants, human medicines, environmental remediation and fish feeding, have been developed. The annual market for humic substances has grown rapidly for these reasons and due to eco-conscious features, but there is a limited supply of natural coal-related resources such as lignite and leonardite from which humic substances are extracted in bulk. The structural similarity between humic substances and lignin suggests that lignocellulosic refinery resulting in lignin residues as a by-product could be a potential candidate for a bulk source of humic-like substances, but structural differences between the two polymeric materials indicate that additional transformation procedures allowing lignin architecture to fully mimic commercial humic substances are required. In this review, we introduce the emerging concept of artificial humification of lignin-related materials as a promising strategy for lignin valorization. First, the core structural features of humic substances and the relationship between these features and the physicochemical properties, natural functions and versatile applications of the substances are described. In particular, the mechanism by which humic substances stimulate the growth of plants and hence can improve crop productivity is highlighted. Second, top-down and bottom-up transformation pathways for scalable humification of small lignin-derived phenols, technical lignins and lignin-containing plant residues are described in detail. Finally, future directions are suggested for research and development of artificial lignin humification to achieve alternative ways of producing customized analogues of humic substances. • Artificial humifications of lignin for versatile applications are discussed. • Top-down ways: alkaline oxidative hydrolysis, composting, vermicomposting, Fenton reaction and Mn-based oxidation. • Bottom-up ways: oxidative polymerization and sodium borohydride reduction. • Potential humification methods to be considered: ozonation, thermal degradation and fermentation with specific microbes. [ABSTRACT FROM AUTHOR]

Melt processing of polymeric materials is a ubiquitous technique for forming, shaping, refining and homogenizing polymers and polymer composites. Melt-processing techniques are the primary manufacturing method of consumer and industrial thermoplastic parts, especially when using commodity polymers with high-throughput production. Melt-processing, however, is underutilized in academic laboratories when developing high value-added materials due to the capital expense of the equipment and relatively large-scale required to carry out such processing. These concerns make pilot-scale melt-processing challenging, particularly for the development of new polymers or polymer composites where materials can only be generated in small-scale at reasonable costs. The current study designs and evaluates a bench-top, sub-milliliter volume extrusion and injection-molding device, which sources parts from current 3D printer technology at minimal expense. The plans presented will open this convenient technique to academic research laboratories interested in pilot-scale experiments. A systematic approach to melt processing of PLA, PLGA, and PCL polymer composites is demonstrated. Characterization of the dispersion of pharmaceuticals, small molecules and nanoparticles in melt processed polymers is presented as a demonstration of potential utility. Image 1 • Schematics for facile assembly of a lab scale mini-injection molding system. • Less than $500 in raw materials, melt processes polymers at up to 250 °C with 100 MPa pressure. • Ideal for small samples 50–500 mg total mass with low dead volume. • Non-newtonian modeling of shear rate inside melt processing system. [ABSTRACT FROM AUTHOR]

Front Cover: Microfluidics and macromolecules are a congeniality to foster the understanding and to direct the engineering of polymer‐based materials and functional entities. This themed issue spotlights on this synergy, focusing on both the analytical and the preparative benefits of microfluidics in polymer science and engineering. Further details can be found in the article by Sebastian Seiffert (article number 1600280). [ABSTRACT FROM AUTHOR]

P. T. Hammond and co‐workers present a technique that uses tangential flow filtration for rapid, high‐yield preparation of biomedically relevant layer‐by‐layer nanoparticles. Diverse nanoparticles with diameters ranging from 40 to 150 nm were prepared from polystyrene, mesoporous silica, and drug‐loaded liposomal cores. Using this technique, nanoparticles could be coated with a broad range of polyelectrolytes including polysaccharides, polypeptides, and synthetic polymers. The prepared nanoparticles are suitable for long‐term storage under refrigerated conditions, as well as for lyophilized, room‐temperature storage. [ABSTRACT FROM AUTHOR]