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A series of novel functional polycarbonates, specifically poly(solketal glycidyl ether carbonate-co-propylene carbonate)s with varying compositions, were synthesized through the ring-opening copolymerization of solketal glycidyl ether, propylene oxide, and carbon dioxide. The reaction was catalyzed by rac-(salcy)Co[sup.III]X complexes with bis(triphenylphosphine)iminium salts as co-catalysts, achieving high selectivity. The resulting terpolymers exhibited number-average molecular weights ranging from 2 × 10[sup.4] to 1 × 10[sup.5] and a narrow, bimodal molecular weight distribution, with dispersities of 1.02–1.07 for each mode. Interestingly, the addition of a small amount of water to the reaction mixture yielded a terpolymer with a unimodal molecular weight distribution and a dispersity of 1.11. Subsequent acidic hydrolysis of the solketal protective groups produced poly(glyceryl glycerol carbonate-co-propylene carbonate). All terpolymers were amorphous, with Tg near or below room temperature. The hydroxyl-functional polycarbonates underwent cyclodepolymerization under milder conditions compared to polycarbonates with protected hydroxyl groups.

3D printing has emerged as one of the most promising tools to overcome the processing and morphological limitations of traditional tissue engineering scaffold design. However, there is a need for improved minimally invasive, void-filling materials to provide mechanical support, biocompatibility, and surface erosion characteristics to ensure consistent tissue support during the healing process. Herein, soft, elastomeric aliphatic polycarbonate-based materials were designed to undergo photopolymerization into supportive soft tissue engineering scaffolds. The 4D nature of the printed scaffolds is manifested in their shape memory properties, which allows them to fill model soft tissue voids without deforming the surrounding material. In vivo, adipocyte lobules were found to infiltrate the surface-eroding scaffold within 2 months, and neovascularization was observed over the same time. Notably, reduced collagen capsule thickness indicates that these scaffolds are highly promising for adipose tissue engineering and repair. Shape memory scaffolds are needed for minimally invasive tissue repair and void filling. Here the authors report on the development of 4D printed polycarbonate-based scaffolds with surface degradation properties which fill voids without deforming tissue and allow for tissue ingrowth with reduced immune response.

Nine urban intertidal regions in Burrard Inlet, Vancouver, British Columbia, Canada, were sampled for plastic debris. Debris included macro and micro plastics and originated from a wide diversity of uses ranging from personal hygiene to solar cells. Debris was characterized for its polymer through standard physiochemical characteristics, then subject to a weak acid extraction to remove the metals, zinc, copper, cadmium and lead from the polymer. Recently manufactured low density polyethylene (LDPE), nylon, polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS) and polyvinyl chloride (PVC) were subject to the same extraction. Data was statistically analyzed by appropriate parametric and non-parametric tests when needed with significance set at P < 0.05. Polymers identified in field samples in order of abundance were; PVC (39), LDPE (28), PS (18), polyethylene (PE, 9), PP (8), nylon (8), high density polyethylene (HDPE, 7), polycarbonate (PC, 6), PET (6), polyurethane (PUR, 3) and polyoxymethylene (POM, 2). PVC and LDPE accounted for 46% of all samples. Field samples of PVC, HDPE and LDPE had significantly greater amounts of acid extracted copper and HDPE, LDPE and PUR significantly greater amounts of acid extracted zinc. PVC and LDPE had significantly greater amounts of acid extracted cadmium and PVC tended to have greater levels of acid extracted lead, significantly so for HDPE. Five of the collected items demonstrated extreme levels of acid extracted metal; greatest concentrations were 188, 6667, 698,000 and 930 μgg-1 of copper, zinc, lead and cadmium respectively recovered from an unidentified object comprised of PVC. Comparison of recently manufactured versus field samples indicated that recently manufactured samples had significantly greater amounts of acid extracted cadmium and zinc and field samples significantly greater amounts of acid extracted copper and lead which was primarily attributed to metal extracted from field samples of PVC. Plastic debris will affect metals within coastal ecosystems by; 1) providing a sorption site (copper and lead), notably for PVC 2) desorption from the plastic i.e., the \"inherent\" load (cadmium and zinc) and 3) serving as a point source of acute trace metal exposure to coastal ecosystems. All three mechanisms will put coastal ecosystems at risk to the toxic effects of these metals.

Metal-coated plastic parts are replacing traditional metallic materials in the automotive industry. Sputtering is an alternative technology that is more environmentally friendly than electrolytic coatings. Most metalized plastic parts are coated with a thin metal layer (~100–200 nm). In this work, the challenge is to achieve thicker films without cracking or without other defects, such as pinholes or pores. Chromium coatings with different thicknesses were deposited onto two different substrates, polycarbonate with and without a base coat, using dc magnetron sputtering in an atmosphere of Ar. Firstly, in order to improve the coating adhesion on the polymer surface, a plasma etching treatment was applied. The coatings were characterized for a wide thickness range from 800 nm to 1600 nm. As the thickness of the coatings increased, there was an increase in the specular reflectivity and roughness of the coatings and changes in morphology due to the columnar growth of the film and a progressive increase in thermal stresses. Furthermore, a decrease in the hardness and the number of pinholes was noticed. The maximum thickness achieved without forming buckling defects was 1400 nm. The tape tests confirmed that every deposited coating showed a good interface adhesion to both polymers.

Human substance needsśś have been enriched by the development of smart-responsive materials possessing unique responsiveness and mechanical variability. However, acquiring these features in photoresponsive energy-driven elastomers is challengeable but highly desirable. Here, we report fabrication of physically-crosslinked elastomers based on an aliphatic polycarbonate terminated with one azobenzene derivative as the end group. Upon irradiation of UV light, the aliphatic polycarbonate shows unusual mechanical transformation from trans-azobenzene-rich elasticity to cis-azobenzene-rich plasticity, which is contrary to the photo-triggered mechanics of other azopolymers. This indicates that stronger interaction may be established between the terminated cis-azobenzenes and the benzene rings in the side chain of polymer, leading to a higher crosslinking density appeared in the cis-azobenzene-rich sample. This azobenzene-terminated polymer is an energy-driven elastomer, which has photo-switchable supramolecular interactions, showing photo-tunable mechanical properties (the half-life period of the cis-azobenzene is 16.9 h). More interestingly, the photoinduced mechanical change occurs at room temperature, enabling the aliphatic polycarbonate to behave as non-thermally switchable ultra-strong adhesive for different substrates, which is specifically suitable for smart dressings to promote wound healing. This switchable mechanical feature of elastomers may be a reference for smart elastomers towards advanced applications. The development of photoresponsive energy-driven elastomers with unique responsiveness and mechanical variability is challenging. Here, the authors describe elastomers based on reversible cis-trans isomerization transition of azobenzene terminated aliphatic polycarbonate, allowing mechanical transformation for smart photo/thermal switchable adhesion and wound healing as medical dressings.

Bead foams serve in a wide variety of applications, from insulation and packaging to midsoles in shoes. However, the currently used materials are limited to somewhat low temperature or exhibit significant changes in modulus in the temperature range of many applications due to their glass transition. By comparison, polycarbonate (PC) exhibits almost constant mechanics for temperatures up to 130 °C. Therefore, it appears as an advantageous base material for bead foams. The aim of the publication is to provide comprehensive data on the properties of expanded PC (EPC) in comparison to already commercially available expanded polypropylene, EPP, and expanded polyethylene-terephthalate, EPET. A special focus is set on the thermo-mechanical properties as these are the most lacking features in current materials. In this frame, dynamic mechanical analysis, and tensile, bending, compression and impact tests at room temperature (RT), 80 °C, and 110 °C are conducted for the three materials of the same density. Already at RT, EPC exhibits superior mechanics compared to its peers, which becomes more pronounced toward higher temperature. This comes from the low sensitivity of properties to temperature as EPC is used below its glass transition. In summary, EPC proves to be an outstanding foam material over a broad range of temperatures for structural applications.

Past work has shown that particle material extrusion (fused particle fabrication (FPF)/fused granular fabrication (FGF)) has the potential for increasing the use of recycled polymers in 3D printing. This study extends this potential to high-performance (high-mechanical-strength and heat-resistant) polymers using polycarbonate (PC). Recycled PC regrind of approximately 25 mm2 was 3D printed with an open-source Gigabot X and analyzed. A temperature and nozzle velocity matrix was used to find useful printing parameters, and a print test was used to maximize the output for a two-temperature stage extruder for PC. ASTM type 4 tensile test geometries as well as ASTM-approved compression tests were used to determine the mechanical properties of PC and were compared with filament printing and the bulk virgin material. The results showed the tensile strength of parts manufactured from the recycled PC particles (64.9 MPa) were comparable to that of the commercial filament printed on desktop (62.2 MPa) and large-format (66.3 MPa) 3D printers. Three case study applications were investigated: (i) using PC as a rapid molding technology for lower melting point thermoplastics, (ii) printed parts for high temperature applications, and (iii) printed parts for high-strength applications. The results show that recycled PC particle-based 3D printing can produce high-strength and heat-resistant products at low costs.

India’s cement industry is the second largest in the world, generating 6.9% of the global cement output. Polycarbonate waste ash is a major problem in India and around the globe. Approximately 370,000 tons of scientific waste are generated annually from fitness care facilities in India. Polycarbonate waste helps reduce the environmental burden associated with disposal and decreases the need for new raw materials. The primary variable in this study is the quantity of polycarbonate waste ash (5, 10, 15, 20 and 25% of the weight of cement), partial replacement of cement, water-cement ratio and aggregates. The mechanical properties, such as compressive strength, split tensile strength and flexural test results, of the mixtures with the polycarbonate waste ash were superior at 7, 14 and 28 days compared to those of the control mix. The water absorption rate is less than that of standard concrete. Compared with those of conventional concrete, polycarbonate waste concrete mixtures undergo minimal weight loss under acid curing conditions. Polycarbonate waste is utilized in the construction industry to reduce pollution and improve the economy. This study further simulated the strength characteristics of concrete made with waste polycarbonate ash using least absolute shrinkage and selection operator regression and decision trees. Cement, polycarbonate waste, slump, water absorption, and the ratio of water to cement were the main components that were considered input variables. The suggested decision tree model was successful with unparalleled predictive accuracy across important metrics. Its outstanding predictive ability for split tensile strength (R 2  = 0.879403), flexural strength (R 2  = 0.91197), and compressive strength (R 2  = 0.853683) confirmed that this method was the preferred choice for these strength predictions.

Commodity polymers are ubiquitous in our society, having replaced many inorganic and metal-based materials due to their versatile properties. However, their functionality heavily relies on the addition of various components known as additives, making it challenging to recycle the polymer fraction of plastic materials effectively. Thus, it is crucial to develop efficient chemical recovery strategies for commodity polymers and additives to facilitate the direct utilization of recovered monomers and additives without additional purification. Here, we develop a strategy for co-upcycling two types of waste commodity polymers, polycarbonate, and polyethylene terephthalate into polyarylate, a high-performance transparent engineering plastic. By incorporating a highly active metal-free ionic liquids catalyst for methanolysis and a two-stage interface polymerization technique with variable temperature control, we successfully prepare polyacrylate film materials from real end-of-life plastics with direct utilization of capping agent impurities in recovered monomers. These materials exhibit excellent thermal performance (Tg = 192.8 °C), transmittance (reach up to 86.73%), and flame-retardant properties (V-0, UL-94), equivalent to those of commercial polyarylate (U-100, about $10000/ton), and could be further easily close-loop recycled. Demonstrated in kilogram-scale experiments and life cycle assessments, this approach offers a low-carbon, environmentally friendly, and economically feasible pathway for upcycling waste commodity polymers. Recycling of commodity plastics remains challenging due to the presence of additives and mixed waste streams. Here the authors develop a strategy for co-upcycling polycarbonate, and polyethylene terephthalate, two types of waste commodity polymers, into polyarylate, a high-performance transparent engineering plastic.

Polycarbonate is an engineering plastic used in a wide range of applications due to its excellent mechanical properties, which are closely related to its molecular structure. We performed coarse-grained molecular dynamics (CGMD) calculations to investigate the effects of topological constraints and spatial distribution on the mechanical performance of a certain range of molecular weights. The topological constraints and spatial distribution are quantified as the number of entanglements per molecule (Ne) and the radius of gyration (Rg), respectively. We successfully modeled molecular structures with a systematic variation of Ne and Rg by controlling two simulation parameters: the temperature profile and Kuhn segment length, respectively. We investigated the effect of Ne and Rg on stress–strain curves in uniaxial tension with fixed transverse strain. The result shows that the structure with a higher radius of gyration or number of entanglements has a higher maximum stress (σm), which is mainly due to a firmly formed entanglement network. Such a configuration minimizes the critical strain (εc). The constitutive relationships between the mechanical properties (σm and εc) and the initial molecular structure parameters (Ne and Rg) are suggested.