Journal of Polymer Science Part A: Polymer Chemistry最新文献

Bioelectronic interfaces establish a communication channel between a living system and an electrical machine. The first examples emerged in the 18th century when batteries were used to “galvanize” muscles and nerves. Today bioelectronic interfaces underpin key medical technologies such as the cardiac pacemaker and emerging ones such as neuroprostheses and brain-machine interfaces. Despite compelling applications in living systems, bioelectronic interfaces employ materials from microelectronics that are rigid, impermeable to water and bioinert. In contrast, electrical phenomena in soft tissues such as muscle and nerve are mediated by ions and molecules solvated in water. This disparity leads to missed opportunities for achieving seamless interfaces and communication that extends beyond electrical stimulation and recording. In this perspective, I discuss opportunities presented by hydrogel materials for building bioelectronic interfaces. This will require new types of hydrogels that support both ionic and electronic conductivity combined with key functions of the extracellular matrix.

Self-healing polymer materials have been a research hotspot in the field of smart materials since their invention. They have self-diagnostic functions and are capable of self-healing small cracks. By applying self-healing materials to flexible electronic devices, the mechanical damage caused by bending, folding and scratching of these devices can be reduced. The reliability and service life of the devices could be improved accordingly. This paper provides a brief overview of self-healing polymers and focuses on their applications in flexible electronic devices. In addition, this paper prospects the future development and challenges of self-healing polymer materials.

Vertically oriented nanoporous cylinders, demonstrating an unprecedented alignment persistence, were produced within freestanding poly(1,1-dimethyl silacyclobutane)-block-polystyrene-block-poly(2-vinyl pyridine) (PDMSB-b-PS-b-P2VP) layers (~15 μm thick) blended with short PS-b-P2VP chains by combining the non-solvent induced phase separation (NIPS) process with a solvent vapor annealing (SVA) treatment. Here, the NIPS step allowed for the formation of an asymmetric and porous PDMSB-b-PS-b-P2VP film having a top surface exhibiting poorly-defined nanopores while the subsequent SVA treatment enabled to produce a symmetric layer that possesses highly-ordered cylindrical nanodomains arranged into a 27 nm period square array. As the unblended NIPS/SVA-made PDMSB-b-PS-b-P2VP monoliths exhibited a mixed orientation of parallel and perpendicular cylinders, a blending strategy was used to achieve tetragonally-packed PDMSB and P2VP nanodomains having an exceptional vertical alignment persistence. Such solvent-annealed (3 h, CHCl₃) PDMSB-b-PS-b-P2VP monoliths blended with 20 wt% of PS-b-P2VP chains showed a water permeance close to the value measured through their parent NIPS-made terpolymer films having poorly-ordered nanopores.

Response: The driving force of my research program is the strong desire to address the crises of plastic pollution, and rapid depletion of fossil resources that are the major feedstocks for polymer production. It can be expected that the current petroleum-based commodity polymers will be eventually replaced in the near future.

In addition, I would encourage early PhD students to begin participation in education and outreach activities beyond lab research. This integration of education and research would help them think of building their own research program in the future and promote the broader impacts of their research, which would in turn inspire them to pursue their long-term research goals.

The cover image was created by Yuanchao Li and Trung Van Nguyen. The treatment of Nafion ionomer films with hot dry gas above their glass transition temperatures induces aggregation of the ionic groups and the formation of separate ionic-group-rich and ionic-group-sparse domains in the films. The latter creates hydrophobic interfaces and transport channels with lower water content and higher oxygen solubility. This novel approach improves water management and oxygen transport in the cathode catalyst layers of the PEM fuel cells which leads to higher electrochemical performance. Details are found in the article from Trung Van Nguyen and colleagues. (DOI: 10.1002/pol.20220774)

There is growing interest in biodegradable and bio-based materials that can replace conventional plastics in applications such as packaging. Polymers based on 2,5-furandicarboxylic acid (FDCA) have been proposed as bio-based analogues for polymers based on terephthalic acid. However, they tend to be brittle, exhibit limited biodegradability, and there are few examples of biocomposites from these polymers. Described here is the preparation of a small library of copolyesters based on FDCA, 1,4-butanediol, and either succinic, adipic or sebacic acid. By incorporating different dicarboxylic acids in varying ratios, the glass transition temperature was tuned from −30 to 41°C and the melting temperature from 104–171°C while maintaining high stability up to ~300°C. Incorporation of aliphatic dicarboxylic acids facilitated blending of the copolymers with hemp powder, with up to 30 wt% hemp incorporated into the polymer containing 60:40 FDCA:sebacic acid. Incorporation of hemp did not substantially alter the thermal properties but increased the moduli of the composites. The copolyesters were susceptible to degradation by Rhizopus oryzae lipase, with the sebacic acid-containing polyester having higher degradability than the succinic acid-containing polyester. Overall, the results demonstrate the promise of the copolyester-hemp blends for applications where they can replace conventional non-degradable plastics.

This work reports that the rheology of ideally monodisperse lambda ($�\lambda$) phage DNA solutions is extremely sensitive to the applied strain in dynamic oscillatory experiments. $�\lambda$ DNA exhibits nonlinearity at strains far smaller than what is observed in conventional synthetic polymers. However, it is found that polydisperse calf thymus DNA does not exhibit the extreme strain sensitivity. By mixing samples of monodisperse $�\lambda$ DNA with the polydisperse calf thymus DNA, we correlate the molecular weight distribution (or polydispersity) to the onset of nonlinear viscoelasticity. We demonstrate that the strain sensitivity weakens as the polydispersity index increases. This is the first work correlating the inception of nonlinear viscoelasticity in entangled polymer system such as lambda DNA solution to the polydispersity of the samples. The experimental data suggests that ideally monodisperse polymer systems are very sensitive to the applied strain and have a very early transition to the nonlinear regime. We conclude that nominally monodisperse synthetic polymers are not sufficiently monodispersed to exhibit the early onset.

To model the engineering performance of components made of polyvinylidene fluoride (PVDF), the 3D elasto-viscoplastic Eindhoven glassy polymer (EGP) model is extended to describe the rate-dependent behavior of PVDF. Careful analysis of the intrinsic behavior of PVDF revealed that the postyield compressive response shows a strain rate-dependence that evolves with increasing deformation. The extension of the constitutive model captures the deformation-dependent evolution of the activation volume and the rate-factor, which describes the driving stress. Given the significant temperature-dependent behavior, the model has been characterized for different temperatures (23, 55 and 75 °C). The accuracy of the model has been validated by means of tension and creep experiments at these temperatures. The constitutive model is implemented in finite element simulations and the results are compared with the experiments. It is shown that the proposed model allows for an accurate prediction of the short- and long-term rate-dependent behavior of PVDF.

Three-dimensional (3D) printing of hydrogels to form complex structures has been widely used in tissue engineering. Projection-based 3D printing (PBP) has faster printing, lower cell damage, and higher printing resolution compared with other 3D printing methods, providing a potential strategy for printing elaborate 3D hydrogel structures. In this review, we introduced the composition and printing process of PBP. We then discuss the study of hydrogels for PBP, including chemical structure modification and property optimization. More importantly, we highlight the potential applications of PBP-based hydrogels in regenerative medicine and tissue engineering, and discuss the current challenges and future prospects of PBP-based hydrogels. Ideas are provided for the study of PBP, hydrogel bioinks, and related fields.

How to properly dispose of waste polymers is a recognized challenge all over the world. Thermal degradation is currently recognized as a promising method for recycling polymer waste into fuels or products with high energy density without polluting the environment. In the present study, the thermal degradation characteristics, kinetics, thermodynamic parameters, and volatiles of a representative and extremely widely-used polymer (micron waste polypropylene [PP]) pyrolysis in nitrogen were investigated. The results indicate that the thermal degradation of micron waste polypropylene can be considered as a one-step reaction with merely one distinct peak on the reaction rate curves. The peak and average reaction rates decrease with the heating rate. The most appropriate reaction model to characterize the thermal degradation is g(α) = 1−(1−α)^1/4. The average values of activation energy and pre-exponential factor are 128.76 kJ/mol and 6.79 × 10⁹ min⁻¹, respectively. The kinetic parameters obtained in this study are all larger than those of PP with the particle size of millimeters or larger. The predicted thermogravimetric curves of thermal degradation are in good agreement with the experimental results. The changes of enthalpy, Gibbs free energy, and entropy show that the thermal degradation of micron waste polypropylene is a non-spontaneous and endothermic reaction. In addition, the concentrations of all volatiles in descending order are: H₂O > Esters (COO)  > CO₂ > Alkanes (CH₃) > R₂CCH₂ > Olefins (CC) > Alcohols (ROH) > Methylene group > CO.