The incorporation of diverse macromolecular blocks into CO2-based polycarbonates offers a promising approach for tailoring the properties of polycarbonates for special needs. In this work, we report ...for the first time the synthesis and characterization of an ABA triblock copolymer polycarbonate-b-polyalkenamer-b-polycarbonate in combination of ROCOP and ROMP via a one-pot route from CO2, epoxides and cycloalkenes. Cis-2-butene-1,4-diol as the bifunctional chain transfer agent was used as a “bridge” for the combination of different blocks as well as an effective regulator for the molecular weight of the polymers. In the one-pot reaction, the conversion of cycloalkenes reached 99.9% within 0.5 h, while the conversion of CHO was initially marginal at 0.5% but gradually increased to 99.7% after 24 h. The significant discrepancy in reaction rates between the two processes enables efficient synergistic reactions within the one-pot system. Specifically, hydroxyl-telechelic polyalkenamer is initially formed via ROMP and subsequently acts as an active species for ROCOP when coordinated with the porphyrin Al catalyst. This one-pot strategy provides a unique and simple method for controllably constructing functional polycarbonates with single-modal molecular weight distributions. By integrating the advantages of polyalkenamers and polycarbonates, this approach proves to be a viable solution for addressing the unsatisfactory thermal properties of aliphatic polycarbonates.
Display omitted
•CO2-based functional polycarbonate prepared via one pot reaction in combination of ROCOP and ROMP.•Bifunctional chain transfer agent as a bridge for polycarbonate and polyalkenamer to achieve block copolymer.•ABA block structure confirmed by 1H NMR, DOSY and MALDI-TOF analysis.
In this work, the flexibility of polycarbonate (PC) membrane was improved by using polyurethane (PU) additive. However, due to the hydrophobic nature of the PU polymer, alumina (Al2O3) nanoparticles ...were incorporated to PC‐PU blend membrane. The prepared membranes have been used in a submerged membrane system to eliminate humic acid molecules from polluted water in both the presence and absence of coagulant (polyaluminum chloride). The obtained results showed that introduction of PU into PC membrane diminished hydrophilicity and enhanced porosity. Moreover, the flexibility of the PC membrane remarkably improved. Introduction of 1.5 wt% Al2O3 to the PC‐PU blend membrane led to enhancement in both porosity and hydrophilicity. Results of morphological studies showed that in the presence of Al2O3 nanostructures, finger‐shaped voids seemed to elongate across the entire thickness of the prepared membrane. Atomic force microscopy images showed that incorporation of PU and Al2O3 to the PC membrane resulted in a smoother surface. The antifouling performance of membranes revealed that the PC‐PU/Al2O3 nanocomposite membrane possessed the most favorable antifouling features owing to its lowest surface roughness as well as highest hydrophilicity. For all membranes utilizing coagulant (PAC), the irreversible fouling ratio and the flux recovery ratio significantly diminished and increased, respectively.
The consumption of heat energy as well as electric power in an exploitation process of a building construction depends among others on properties of materials applied to construct its partitions. ...Increasingly, glass is being replaced by plastics in transparent partitions, including multi-wall polycarbonate sheets. Light transmission and solar radiation transferred to the object’s inside through transparent partitions are decisive factors for its lighting and energy balance. The present paper presents an analysis, on an experimental basis, of the changes of total solar transmittance (TST) for a clear twin-wall polycarbonate sheet with a rectangular structure applied as a swimming pool enclosure. Research shows that values of the above parameter do not depend meaningfully on cloudiness but on time of day. Values of TST can change in the daytime depending on incidence angles and on shares of direct and diffusive solar radiation in global solar radiation. TST values are in the range 0.6–0.7, and they are lower than the value of 0.8, which is given by the producer in the product card.
Currently available focal knee resurfacing implants (FKRIs) are fully or partially composed of metals, which show a large disparity in elastic modulus relative to bone and cartilage tissue. Although ...titanium is known for its excellent osseointegration, the application in FKRIs can lead to potential stress‐shielding and metal implants can cause degeneration of the opposing articulating cartilage due to the high resulting contact stresses. Furthermore, metal implants do not allow for follow‐up using magnetic resonance imaging (MRI).To overcome the drawbacks of using metal based FKRIs, a biomimetic and MRI compatible bi‐layered non‐resorbable thermoplastic polycarbonate‐urethane (PCU)‐based FKRI was developed. The objective of this preclinical study was to evaluate the mechanical properties, biocompatibility and osteoconduction of a novel Bionate® 75D ‐ zirconium oxide (B75D‐ZrO2) composite material in vitro and the osseointegration of a B75D‐ZrO2 composite stem PCU implant in a caprine animal model. The tensile strength and elastic modulus of the B75D‐ZrO2 composite were characterized through in vitro mechanical tests under ambient and physiological conditions. In vitro biocompatibility and osteoconductivity were evaluated by exposing human mesenchymal stem cells to the B75D‐ZrO2 composite and culturing the cells under osteogenic conditions. Cell activity and mineralization were assessed and compared to Bionate® 75D (B75D) and titanium disks. The in vivo osseointegration of implants containing a B75D‐ZrO2 stem was compared to implants with a B75D stem and titanium stem in a caprine large animal model. After a follow‐up of 6 months, bone histomorphometry was performed to assess the bone‐to‐implant contact area (BIC). Mechanical testing showed that the B75D‐ZrO2 composite material possesses an elastic modulus in the range of the elastic modulus reported for trabecular bone. The B75D‐ZrO2 composite material facilitated cell mediated mineralization to a comparable extent as titanium. A significantly higher bone‐to‐implant contact (BIC) score was observed in the B75D‐ZrO2 implants compared to the B75D implants. The BIC of B75D‐ZrO2 implants was not significantly different compared to titanium implants. A biocompatible B75D‐ZrO2 composite approximating the elastic modulus of trabecular bone was developed by compounding B75D with zirconium oxide. In vivo evaluation showed an significant increase of osseointegration for B75D‐ZrO2 composite stem implants compared to B75D polymer stem PCU implants. The osseointegration of B75D‐ZrO2 composite stem PCU implants was not significantly different in comparison to analogous titanium stem metal implants.
The alternating copolymerization of biorenewable limonene dioxide with carbon dioxide (CO2) catalyzed by a zinc β‐diiminate complex is reported. The chemoselective reaction results in linear ...amorphous polycarbonates that carry pendent methyloxiranes and exhibit glass transition temperatures (Tg) up to 135 °C. These polycarbonates can be efficiently modified by thiols or carboxylic acids in combination with lithium hydroxide or tetrabutylphosphonium bromide as catalysts, respectively, without destruction of the main chain. Moreover, polycarbonates bearing pendent cyclic carbonates can be quantitatively prepared by CO2 insertion catalyzed by lithium bromide.
From biobased diepoxide to linear epoxy PCs: A sustainable poly(limonene‐8,9‐oxide carbonate) was prepared by chemoselective copolymerization of limonene dioxide and CO2. The pendent 2‐methyloxiranyl groups along the polymer chain permit the facile post‐modification and insertion of CO2 to generate cyclic carbonates as functional side groups.
From an industrial/engineering point of view, the greatest demerit of solely isosorbide (ISB)-based polycarbonate is its fragility; this is considerably overcome in this study by using a dual-diol ...strategy with 1,4-cyclohexanedimethanol (CHDM). A series of copolycarbonates of ISB, a bio-derived diol with a rigid heterocyclic structure, and ductile CHDM monomers with diphenyl carbonate were prepared by transesterification polymerization. The weight-average molecular weight of the polycarbonates gradually decreases as the ratio of ISB increases; however, their Tg and storage modulus increase. The ultimate elongation of the copolycarbonates is enhanced from 4.6 to 20% as the content of CHDM is increased from 30 to 80 mol%. ISB content greater than 50 mol% makes the copolycarbonates strong but brittle, and ISB content less than 50 mol% makes the copolycarbonates ductile but soft. The polycarbonate with 70/30 mol% of ISB/CHDM shows a 1.25-fold higher Young's modulus, 1.05-fold higher ultimate tensile strength, and one-grade higher pencil hardness than the bisphenol-A (BPA)-based polycarbonate. Interestingly, the hydrophilic ISB content does not affect the degree of hydrophilicity of the copolycarbonate samples. Water droplet contact angles are in the range of 81–87°, comparable to that of the BPA-based polycarbonate.
Display omitted
•Synthesis of copolycarbonates of bio-based isosorbide and 1,4-cyclohexanedimethanol.•As the isosorbide content increased, Tg and the degree of elasticity increased.•Mechanical properties were tuned from ductile to strong by varying ISB/CHDM ratios.•1.25-fold higher Young's modulus, higher pencil hardness than the BPA-polycarbonate.•Comparable hydrophilicity of copolycarbonates with the BPA-polycarbonate.
Promising biomaterials should be tested in appropriate large animal models that recapitulate human inflammatory and regenerative responses. Previous studies have shown tyrosine‐derived polycarbonates ...(TyrPC) are versatile biomaterials with a wide range of applications across multiple disciplines. The library of TyrPC has been well studied and consists of thousands of polymer compositions with tunable mechanical characteristics and degradation and resorption rates that are useful for nerve guidance tubes (NGTs). NGTs made of different TyrPCs have been used in segmental nerve defect models in small animals. The current study is an extension of this work and evaluates NGTs made using two different TyrPC compositions in a 1 cm porcine peripheral nerve repair model. We first evaluated a nondegradable TyrPC formulation, demonstrating proof‐of‐concept chronic regenerative efficacy up to 6 months with similar nerve/muscle electrophysiology and morphometry to the autograft repair control. Next, we characterized the acute regenerative response using a degradable TyrPC formulation. After 2 weeks in vivo, TyrPC NGT promoted greater deposition of pro‐regenerative extracellular matrix (ECM) constituents (in particular collagen I, collagen III, collagen IV, laminin, and fibronectin) compared to commercially available collagen‐based NGTs. This corresponded with dense Schwann cell infiltration and axon extension across the lumen. These findings confirmed results reported previously in a mouse model and reveal that TyrPC NGTs were well tolerated in swine and facilitated host axon regeneration and Schwann cell infiltration in the acute phase across segmental defects ‐ likely by eliciting a favorable neurotrophic ECM milieu. This regenerative response ultimately can contribute to functional recovery.
An impedimetric human papilloma virus (HPV) DNA biosensor based on gold nanotubes (AuNTs) in label free detection was materialized. The AuNTs decorated nanoporous polycarbonate (AuNTs-PC) template as ...biosensor electrode was fabricated by electrodeposition method. The single strand DNA (ss-DNA) probe was covalently immobilized onto the AuNTs-PC electrode. The hybridization of target sequences with the ss-DNA probe was observed by the electrochemical impedance spectroscopy (EIS). The biosensor showed high selectivity and could differentiate between the complementary, mismatch and non-complementary DNA sequences. The EIS measurements were matched to Randle's equivalent circuit. The negatively-charged HPV DNA oligonucleotides under external electric field were oriented in a preferred direction and the bio-sensing responses were intensified by controlling the immobilization and hybridization of the sequences on the AuNTs surface. The fabricated DNA biosensor under electric field amplification was stable up to six weeks and demonstrated 97% of its initial detection responses. The biosensor displayed the HPV DNA hybridization detection in very low concentrations in the linear response ranges of 0.01 pM–1 μM and was able to acquire a limit of detection (LOD) of 1 fM.
Display omitted
•Impedimetric human papillomavirus DNA biosensor by AuNTs-PC electrode was fabricated.•The EIS response was intensified by AuNTs and electric field to acquire LOD of 1fM.•Biosensor in label free detection showed the good linear ranges of 0.01pM to 1μM.•Biosensor could highly specify ds-DNA from the mismatch and non-complementary targets.•Biosensor was stable up to 6 weeks and showed 97% of its initial detection responses.
Abstract
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.
Although polycarbonate (PC) is widely used in various applications, its inherent hydrophobicity limits its potential in applications that require high light transmittance due to surface fog caused by ...changes in temperature or humidity in the environment. This work presents a facile method to fabricate transparent antifogging coatings on PC substrates based on poly(2-hydroxyethyl acrylamide-co-2-aminoethyl methacrylate) (P(HEAA-co-AEMA)), in which the AEMA segments have an amino functional group that can react with the ester group on the surface of the PC substrate to form covalent urethane bonds during the heat curing process, avoiding the problems of coating susceptibility to mechanical damage, ease of peeling, etc. Moreover, HEAA units are employed as hydrophilic groups, providing antifogging performance. These antifogging coatings can be easily obtained by coating P(HEAA-co-AEMA) copolymers on PC substrates at room temperature and then curing them by thermal treatment. These transparent coatings exhibited excellent antifogging and self-cleaning performance. Furthermore, the coatings exhibited good adhesion in the cross-cut test and thermal stability in the hot water resistance test. Therefore, the present P(HEAA-co-AEMA) copolymer coatings are promising for practical antifogging applications.
Display omitted
•The preparation of P(HEAA-co-AEMA) uses nontoxic and eco-friendly solvents, making it suitable for widespread applications.•The antifogging coating can be covalently bonded to the PC substrate, effectively preventing susceptibility to mechanical damage and peeling.•The coating has excellent antifogging and self-cleaning properties, as well as heat-resistant boiling properties.
PDF
