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The translocation of a polymer through a pore that is much smaller than its size is a fundamental and actively researched topic in polymer physics. An understanding of the principles governing polymer translocation provides important guidance for various practical applications, such as the separation and purification of polymers, nanopore-based single-molecule deoxyribonucleic acid/ribonucleic acid(DNA/RNA) sequencing, transmembrane transport of DNA or RNA, and infection of bacterial cells by bacteriophages. The past several decades have seen great progresses on the study of polymer translocation. Here we present an overview of theoretical, experimental, and simulational stduies on polymer translocation, focusing on the roles played by several important factors, including initial polymer conformations, external fields, polymer topology and architectures, and confinement degree. We highlight the physical mechanisms of different types of polymer translocations, and the main controversies about the basic rules of translocation dynamics. We compare and contrast the behaviors of force-induced versus flow-induced translocations and the effects of unknotted versus knotted polymers. Finally, we mention several opportunities and challenges in the study of polymer translocation. [ABSTRACT FROM AUTHOR]

A photo-controlled approach is developed to regulate the interpenetrating polymer network (IPN) topology by varying the connecting structure between the first and second networks. The approach is based on multifunctional inimer (Vinyl-oNB-Br) possessing three moieties, i.e., an acrylate-based double bond for incorporation within a polymer network, a Br group for grafting polymerization to get connect-IPN (c-IPN), and an o-nitrobenzyl spacer for photocleaving to convert the c-IPN to disconnected-IPN (d-IPN) with UV light irradiation. Such design allows for finely controlling the connection degree between two networks. A systematic study on the mechanical property of a series of samples with different connection degrees thus can be conducted. The results reveal that decreasing the connecting degree between two networks of IPN made a negligible contribution to materials' mechanical properties. [ABSTRACT FROM AUTHOR]

The "solid-liquid" behavior of vitrimers have not been systematically investigated. Herein, a series of "solid-liquid" vitrimers bearing varying contents of dynamic boronic ester bonds were synthesized via thiol-ene click reactions. These vitrimers allow for flexibile modulation of their network structures and thus show a range of intriguing properties including high stretchability, flexible transition from elasticity to plasticity, strong strain rate dependence, and solid-liquid performance. The dynamic association rate of boronic ester bonds within these vitrimers could be apparently accelerated via increasing the content of boronic ester, which could be used to shape-program the flat vitrimer films into various complex 3D structures just with external force. Materials with such versatile dynamic behavior may open up a range of new applications. [ABSTRACT FROM AUTHOR]

Electrospun poly(vinylidene fluoride) (PVDF) nanofiber web has been widely utilized as a functional material in various flexible sensors and generators due to its high piezoelectricity, ease processability, and low cost. Among all the crystalline phases of PVDF, β-phase is a key property for PVDF nanofiber web, because the content of β-phase is directly proportional to piezoelectric performance of PVDF nanofiber web. Herein, the impact of graphene content (GC), tip-to-collector distance (TCD), and rotational speed of collector (RSC), as well as their interactions on the β-phase formation of PVDF nanofiber web is systematically investigated via design of experimental method. The fraction of each crystalline phase of PVDF nanofiber web is calculated by FTIR spectra, and the crystallinity is determined by XRD patterns. The influences of GC, TCD, and RSC on both β-phase fraction and crystallinity of PVDF nanofiber are analyzed using Minitab program. The results show that GC, TCD, and RSC all have significant effect on the β-phase content of PVDF nanofiber web, and GC is the most significant one. In addition, an optimal electrospinning condition (GC = 1 wt%, TCD = 4 cm, and RSC = 2000 r-min−1) to fabricate high β-phase crystallinity of PVDF nanofiber web is drawn, under which the crystallinity can reach 41.7%. The contributions in this study could provide guidance for future research on fabricating high performance PVDF nanofiber web based sensors or generators. [ABSTRACT FROM AUTHOR]

Well-defined pH-responsive poly( ε-caprolactone)-graft- β-cyclodextrin-graft-poly(2-(dimethylamino)ethylmethacrylate)- co-poly(ethylene glycol) methacrylate amphiphilic copolymers (PCL- g- β-CD- g-P(DMAEMA- co-PEGMA)) were synthesized using a combination of atom transfer radical polymerization (ATRP), ring opening polymerization (ROP) and 'click' chemistry. Successful synthesis of polymers was confirmed by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (H-NMR), and gel permeation chromatography (GPC). Then, the polymers could selfassemble into micelles in aqueous solution, which was demonstrated by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The pH-responsive self-assembly behavior of these copolymers in water was investigated at different pH values of 7.4 and 5.0 for controlled doxorubicin (DOX) release, and these results revealed that the release rate of DOX could be effectively controlled by altering the pH, and the release of drug loading efficiency (DLE) was up to 88% ( W/ W). CCK-8 assays showed that the copolymers had low toxicity and possessed good biodegradability and biocompatibility, whereas the DOX-loaded micelles remained with high cytotoxicity for HeLa cells. Moreover, confocal laser scanning microscopy (CLSM) images revealed that polymeric micelles could actively target the tumor site and the efficient intracellular DOX release from polymeric micelles toward the tumor cells further confirmed the anti-tumor effect. The DOX-loaded micelles could easily enter the cells and produce the desired pharmacological action and minimize the side effect of free DOX. These results successfully indicated that pH-responsive polymeric micelles could be potential hydrophobic drug delivery carriers for cancer targeting therapy with sustained release. [ABSTRACT FROM AUTHOR]

Herein, we present a novel way for the production of self-healing hydrogels with stretch beyond 4200% than their initial length and relatively high tensile strength (0.1-0.25 MPa). Furthermore, the hydrogel was insensitive to notch. Even for the samples containing V-notches, a stretch of 2300% was demonstrated. The hydrogels were developed by in situ crosslinking of the self-assembled colloidal poly(acrylic acid) (PAA)/functionalized polyhedral oligomeric silsesquioxane (POSS) micelles. This was achieved by the addition of functionalized polyhedral oligomeric silsesquioxane with tertiary amines and hydroxyls (POSS-AH) into the PAA reaction solution. The POSS-AH led to micellar growth, then the dualcrosslinked network was constructed. One type of crosslink was formed by hydrogen-bonding and ionic interactions between PAA chains and POSS-AH, the other type of crosslink was formed by covalent bonds between PAA and bis( N,N'-methylenebis-acrylamide). [ABSTRACT FROM AUTHOR]