Individual cell modification with cell surface specific atom transfer radical polymerization for enhanced Cr(VI) removal.

Modifying cells with polymers on the surface can enable them to gain or enhance function with various applications, wherein the atom transfer radical polymerization (ATRP) has garnered significant potential due to its biocompatibility. However, specifically initiating ATRP from the cell surface for in-situ modification remains challenging. This study established a bacterial surface-initiated ATRP method and further applied it for enhanced Cr(VI) removal. The cell surface specificity was facilely achieved by cell surface labelling with azide substrates, following alkynyl ATRP initiator specifically anchoring with azide-alkyne click chemistry. Then, the ATRP polymerization was initiated from the cell surface, and different polymers were successfully applied to in-situ modification. Further analysis revealed that the modification of Shewanella oneidensis with poly (4-vinyl pyridine) and sodium polymethacrylate improved the heavy metal tolerance and enhanced the Cr(VI) removal rate of 2.6 times from 0.088 h-1 to 0.314 h-1. This work provided a novel idea for bacterial surface modification and would extend the application of ATRP in bioremediation.

Modern Trends in Polymerization-Induced Self-Assembly.

Polymerization-induced self-assembly (PISA) is a powerful and versatile technique for producing colloidal dispersions of block copolymer particles with desired morphologies. Currently, PISA can be carried out in various media, over a wide range of temperatures, and using different mechanisms. This method enables the production of biodegradable objects and particles with various functionalities and stimuli sensitivity. Consequently, PISA offers a broad spectrum of potential commercial applications. The aim of this review is to provide an overview of the current state of rational synthesis of block copolymer particles with diverse morphologies using various PISA techniques and mechanisms. The discussion begins with an examination of the main thermodynamic, kinetic, and structural aspects of block copolymer micellization, followed by an exploration of the key principles of PISA in the formation of gradient and block copolymers. The review also delves into the main mechanisms of PISA implementation and the principles governing particle morphology. Finally, the potential future developments in PISA are considered.

An Innovative Approach for Tailoring Molecularly Imprinted Polymers for Biosensors-Application to Cancer Antigen 15-3.

This work presents a novel approach for tailoring molecularly imprinted polymers (MIPs) with a preliminary stage of atom transfer radical polymerization (ATRP), for a more precise definition of the imprinted cavity. A well-defined copolymer of acrylamide and N,N'-methylenebisacrylamide (PAAm-co-PMBAm) was synthesized by ATRP and applied to gold electrodes with the template, followed by a crosslinking reaction. The template was removed from the polymer matrix by enzymatic/chemical action. The surface modifications were monitored via electrochemical impedance spectroscopy (EIS), having the MIP polymer as a non-conducting film designed with affinity sites for CA15-3. The resulting biosensor exhibited a linear response to CA15-3 log concentrations from 0.001 to 100 U/mL in PBS or in diluted fetal bovine serum (1000×) in PBS. Compared to the polyacrylamide (PAAm) MIP from conventional free-radical polymerization, the ATRP-based MIP extended the biosensor's dynamic linear range 10-fold, improving low concentration detection, and enhanced the signal reproducibility across units. The biosensor demonstrated good sensitivity and selectivity. Overall, the work described confirmed that the process of radical polymerization to build an MIP material influences the detection capacity for the target substance and the reproducibility among different biosensor units. Extending this approach to other cancer biomarkers, the methodology presented could open doors to a new generation of MIP-based biosensors for point-of-care disease diagnosis.

Analysis of the degradation and crystallization behavior during the thermal degradation of poly(lactic acid)/modified hectorite nanocomposites films by simultaneous rheology and FTIR technology.

This study presents the synthesis of Hec-g@PS through the innovative surface modification of hectorite via photocatalytic atom transfer radical polymerization (ATRP). Then, PLA/Hec-g@PS nanocomposites films was prepared with Hec-g@PS as additives by blown molding technique. Furthermore, the thermal degradation kinetics and crystallization kinetics during the thermal degradation of PLA based nanocomposites films were investigated with simultaneous rheology and FTIR technology. The findings indicated that the activation energies for PLA and PLA/Hec-g@PS were -54,702.12 J/mol and -107,963.47 J/mol, respectively, demonstrating that Hec-g@PS substantially influenced PLA thermal stability. Additionally, while the crystallization rates of PLA based films decreased with rising degradation temperatures. Quantum chemical calculations revealed that the mode of interaction between Hec-g@PS and PLA was mainly dominated by dispersion, supplemented by electrostatic and induced interactions of -22.2103 kcal/mol, -16.0779 kcal/mol and -5.4954 kcal/mol, respectively. The combination of crystallization kinetics and quantum chemical calculations further confirmed that Hec-g@PS promoted the alignment of PLA molecular chains due to the enhanced interaction force between them. Hec-g@PS functioned as a nucleating agent, facilitating PLA crystallization and effectively mitigated its thermal degradation. Hec-g@PS as a nucleating agent provides valuable insights into the potential application prospects of biodegradable materials, particularly in the fields of biomedicine and packaging.

Precise Regulation in Chain-Edge Structural Microenvironments of 1D Covalent Organic Frameworks for Photocatalysis.

Covalent organic frameworks (COFs) constitute a promising research topic for photocatalytic reactions, but the rules and conformational relationships of 1D COFs are poorly defined. Herein, the chain edge structure is designed by precise modulation at the atomic level, and the 1D COFs bonded by C, O, and S elements is directionally prepared for oxygen-tolerant photoinduced electron transfer-atom transfer radical polymerization (PET-ATRP) reactions. It is demonstrated that heteroatom-type chain edge structures (─O─, ─S─) lead to a decrease in intra-plane conjugation, which restricts the effective transport of photogenerated electrons along the direction of the 1D strip. In contrast, the all-carbon type chain edge structure (─C─) with higher intra-plane conjugation not only reduces the energy loss of photoexcited electrons but also enhances the carrier density, which exhibits the optimal photopolymerization performance. This work offers valuable guidance in the exploitation of 1D COFs for high photocatalytic performance. This work offers valuable guidance in the exploitation of 1D COFs for high photocatalytic performance.

Copper Nanodrugs by Atom Transfer Radical Polymerization.

In this study, some copper catalysts used for atom transfer radical polymerization (ATRP) were explored as efficient anti-tumor agents. The aqueous solution of copper-containing nanoparticles with uniform spheric morphology was in situ prepared through a copper-catalyzed activator generated by electron transfer (AGET) ATRP in water. Nanoparticles were then directly injected into tumor-bearing mice for antitumor chemotherapy. The copper nanodrugs had prolonged blood circulation time and enhanced accumulation at tumor sites, thus showing potent antitumor activity. This work provides a novel strategy for precise and large-scale preparation of copper nanodrugs with high antitumor activity.

Quasi-Chromophores Segregated by Single-Chain Nanoparticles of Fluorinated Zwitterionic Random Copolymers Showing Remarkably Enhanced Fluorescence Emission Capable of Fluorescent Cell Imaging.

Organic and polymer fluorescent nanomaterials are a frontier research focus. Here in this work, a series of fluorinated zwitterionic random copolymers end-attached with a quasi-chromophoric group of pyrene or tetraphenylethylene (TPE) are well synthesized via atom transfer radical polymerization with activators regenerated by electron transfer (ARGET ATRP). Those random copolymers with total degree of polymerization 100 or 200 are able to produce fluorescent single-chain nanoparticles (SCNPs) through intra-chain self-folding assembly with quite uniform diameters in the range of 10-20 nm as characterized by dynamic light scattering and transmission electron microscopy. By virtue of the segregation or confinement effect, both SCNPs functionalized with pyrene or TPE group are capable of emitting fluorescence, with pyrene tethered SCNPs exhibiting stronger fluorescence emission reaching the highest quantum yield ≈20%. Moreover, such kind of fluorescent SCNPs manifest low cytotoxicity and good cell imaging performance for Hela cells. The creation of fluorescent SCNPs through covalently attached one quasi-chromophore to the end of one fluorinated zwitterionic random copolymer provides an alternative strategy for preparing polymeric luminescence nanomaterials, promisingly serving as a new type of fluorescent nanoprobes for biological imaging applications.

A Versatile Approach for the Synthesis of Antimicrobial Polymer Brushes on Natural Rubber/Graphene Oxide Composite Films via Surface-Initiated Atom-Transfer Radical Polymerization.

A simple strategy was adopted for the preparation of an antimicrobial natural rubber/graphene oxide (NR/GO) composite film modified through the use of zwitterionic polymer brushes. An NR/GO composite film with antibacterial properties was prepared using a water-based solution-casting method. The composited GO was dispersed uniformly in the NR matrix and compensated for mechanical loss in the process of modification. Based on the high bromination activity of α-H in the structure of cis-polyisoprene, the composite films were brominated on the surface through the use of N-bromosuccinimide (NBS) under the irradiation of a 40 W tungsten lamp. Polymerization was carried out on the brominated films using sulfobetaine methacrylate (SBMA) as a monomer via surface-initiated atom transfer radical polymerization (SI-ATRP). The NR/GO composite films modified using polymer brushes (PSBMAs) exhibited 99.99% antimicrobial activity for resistance to Escherichia coli and Staphylococcus aureus. A novel polymer modification strategy for NR composite materials was established effectively, and the enhanced antimicrobial properties expand the application prospects in the medical field.

Fe3O4/PMMA with Well-Arranged Structures Synthesized through Magnetic Field-Assisted Atom Transfer Radical Polymerization.

Particle- or fiber-reinforced polymer composites with controlled orientations are attracting interest and applications producing innovative materials, biological constructs, and energy devices. To gain the controlled orientations, filed-assisted synthesis is widely selected for its easy operation and control. In this paper, we designed magnetic field-assisted equipment and synthesized a magnetic polymer composite Fe3O4/PMMA with a well-arranged layers structure by combining the magnetic field with atom transfer radical polymerization (ATRP). During the polymerization of polymer composites, the magnetic nanoparticles were surrounded by monomers. With the growth of polymer chains, the magnetic particles pushed polymer chains to move according to a specific direction and form a well-arranged structure under the magnetic fields. The existence of a well-arranged layered structure of the composites gives potential guidance for controlling the micro-structure by adding an extra field during the polymerization process. The experimental results provided a possible design to influence the macroscale properties through control of the micro-structure of polymer composites.

T790M mutation upconversion fluorescence biosensor via mild ATRP strategy and site-specific DNA cleavage of restriction endonuclease.

A unique combination of a specific nucleic acid restriction endonuclease (REase) and atom transfer radical polymerization (ATRP) signal amplification strategy was employed for the detection of T790M mutations prevalent in the adjuvant diagnosis of lung cancer. REase selectively recognizes and cleaves T790M mutation sites on double-stranded DNA formed by hybridization of a capture sequence and a target sequence. At the same time, the ATRP strategy resulted in the massive aggregation of upconverted nanoparticles (UCNPs), which significantly improved the sensitivity of the biosensor. In addition, the UCNPs have excellent optical properties and can eliminate the interference of autofluorescence in the samples, thus further improving the detection sensitivity. The proposed upconversion fluorescent biosensor is characterized by high specificity, high sensitivity, mild reaction conditions, fast response time, and a detection limit as low as 0.14 fM. The performance of the proposed biosensor is comparable to that of clinical PCR methods when applied to clinical samples. This work presents a new perspective for assisted diagnosis in the pre-intervention stage of tumor diagnostics in the early stage of precision oncology treatments.

S/N/O-Enriched Carbons from Polyacrylonitrile-Based Block Copolymers for Selective Separation of Gas Streams.

A series of polyacrylonitrile (PAN)-based block copolymers with poly(methyl methacrylate) (PMMA) as sacrificial bock were synthesized by atom transfer radical polymerization and used as precursors for the synthesis of porous carbons. The carbons enriched with O- and S-containing groups, introduced by controlled oxidation and sulfuration, respectively, were characterized by Raman spectroscopy, scanning electron microscopy, and X-ray photoelectron spectrometry, and their surface textural properties were measured by a volumetric analyzer. We observed that the presence of sulfur tends to modify the structure of the carbons, from microporous to mesoporous, while the use of copolymers with a range of molar composition PAN/PMMA between 10/90 and 47/53 allows the obtainment of carbons with different degrees of porosity. The amount of sacrificial block only affects the morphology of carbons stabilized in oxygen, inducing their nanostructuration, but has no effect on their chemical composition. We also demonstrated their suitability for separating a typical N2/CO2 post-combustion stream.

Block Copolymers of Polyolefins with Polyacrylates: Analyzing and Improving the Blocking Efficiencies Using MILRad/ATRP Approach.

Despite their industrial ubiquity, polyolefin-polyacrylate block copolymers are challenging to synthesize due to the distinct polymerization pathways necessary for respective blocks. This study utilizes MILRad, metal-organic insertion light-initiated radical polymerization, to synthesize polyolefin-b-poly(methyl acrylate) copolymer by combining palladium-catalyzed insertion-coordination polymerization and atom transfer radical polymerization (ATRP). Brookhart-type Pd complexes used for the living polymerization of olefins are homolytically cleaved by blue-light irradiation, generating polyolefin-based macroradicals, which are trapped with functional nitroxide derivatives forming ATRP macroinitiators. ATRP in the presence of Cu(0), that is, supplemental activators and reducing agents , is used to polymerize methyl acrylate. An increase in the functionalization efficiency of up to 71% is demonstrated in this study by modifying the light source and optimizing the radical trapping condition. Regardless of the radical trapping efficiency, essentially quantitative chain extension of polyolefin-Br macroinitiator with acrylates is consistently demonstrated, indicating successful second block formation.

Bifunctional fluorescent molecularly imprinted resin based on carbon dot for selective detection and enrichment of 2,4-dichlorophenoxyacetic acid in lettuce.

The work provided a method for synthesizing a simple fluorescent molecularly imprinted polymer by surface-initiated atom transfer radical polymerization (SI-ATRP) and its application in real sample. Poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) microspheres were selected as a matrix, 4-vinylpyridine, ethylene glycol dimethacrylate, 2,4-dichlorophenoxyacetic acid (2,4-D) as functional monomer, cross-linker and template molecule, respectively, to fabricate MAR@MIP with core-shell structure. For comparison, carbon dot (CD) as a fluorescence source was synthesized with o-phenylenediamine and tryptophan as precursors via hydrothermal method and integrated into MIP to acquire MAR@CD-MIP. MAR@CD-NIP was also prepared without adding the template molecule. The adsorption capacity of MAR@CD-MIP reached 104 mg g-1 for 2,4-D, which was higher than that of MAR@MIP (60 mg g-1). However, the adsorption capacity of MAR@CD-NIP was only 13.2 mg g-1. The linear range of fluorescence detection for 2,4-D was 18-72 µmol/L, and the limit of detection (LOD) was 0.35 µmol/L. The fluorescent MAR@CD-MIP was successfully applied in enrichment of lettuce samples. The recoveries of the three spiked concentrations of 2,4-D in lettuce were tested by fluorescence spectrophotometry and ranged in 97.3-101.7 %. Meanwhile, the results were also verified by HPLC. As a result, bi-functional molecularly imprinted resin was successfully fabricated to detect and enrich 2,4-D in real samples, and exhibited good selectivity, sensitivity and great application prospect in food detection.

Synthesis of a novel photochemical and thermoresponsive diblock biomaterial with end-functionalized zinc porphyrin.

Porphyrin compound-based photochemical molecules and biomaterials have been synthesized for photosensitivity and bioimaging experiments. However, most porphyrin photosensitizers have limited application in biological environments owing to severe aggregation in aqueous solutions. In the present study, we prepared amphipathic and photosensitive copolymers using zinc porphyrin via consecutive atom transfer-free radical polymerizations (ATRPs) comprising photoresponsive and thermosensitive chain segments. Furthermore, we evaluated the photocatalytic activity of the copolymer for methylene blue (MB) in water. Methods: First, we synthesized a photoresponsive ain segment of poly (6-[4-(4-methoxyphenylazo)phenoxy]hexyl methacrylate) (ZnPor-PAzo); then, ZnPor-PAzo was used as a macroinitiator and was polymerized with N-isopropylacrylamide (NIPAM) via ATRPs to obtain a novel photochemical and thermoresponsive diblock biomaterial with end-functionalized zinc porphyrin [(ZnPor-PAzo)-PNIPAMs]. Results: The polydispersity index (M w/M n) of (ZnPor-PAzo)-PNIPAMs was 1.19-1.32. Furthermore, its photoresponsive and thermosensitive characteristics were comprehensively studied. Discussion: The end-functionalized diblock copolymer (ZnPor-PAzo)-PNIPAM exhibits obvious fluorescence and efficient photocatalytic activity for aqueous MB under visible light.

Facile Strategy to Prepare Poly(ionic liquid)-Coated Solid Polymer Electrolytes through Layer-by-Layer Assembly.

The inability of solid polymer electrolytes to preserve strong mechanical strength with high ionic conductivity hinders the commercialization of lithium metal batteries (LMBs). The success of fabricating layer-by-layer (LbL)-assembled electrolytes has realized the application of flexible solid polymer electrolytes in electrochemical devices. Here, we demonstrate a rational strategy to construct solid electrolytes coated with multiple ultrathin layers of polyanions (poly(sodium 4-styrenesulfonate)) and polycations (linear poly(1-butyl-3-(4-vinylbenzyl)-1H-imidazolium chloride) (BVIC)/linear poly(PEG4-VIC)/SiO2-g-poly(PEG4-VIC)) using an LbL assembly method. Poly(ionic liquid) backbones and PEG side groups are employed to facilitate the transport of lithium ions via the segmental motion of the macromolecular matrix. The fabricated free-standing membranes exhibited good ionic conductivities of 9.03-10 × 10-4 S cm-1. Furthermore, a Li/LiFePO4 cell assembled with the LbL-membrane electrolytes exhibits an initial high discharge capacity of 143-158 mAhg-1 at 60 °C with high columbic efficiency. This approach, which combines polymer synthesis and LbL self-assembly, is an effective and facile route to fabricate solid polymer electrolyte membranes with superior ionic conductivity and mechanical robustness, which are useful for electrochemical devices and high-voltage battery applications.

Modification of nanocellulose via atom transfer radical polymerization and its reinforcing effect in waterborne UV-curable resin.

Cellulose nanocrystals (CNCs) are green reinforcing materials, and their potential has been evaluated in the preparation of waterborne UV-curable resin composites with high-performance. Herein, we present a novel and scalable approach for preparing surface-modified CNCs with acrylic-based polymers to strengthen the compatibility and interaction between CNCs and UV-curable resins. Using tert-butyl acrylate as the monomer, the nanocellulose grafted copolymer CNC-g-PtBA was successfully synthesized via atom transfer radical polymerization (ATRP) in the presence of a macromolecular initiator. Then, the CNC-g-PtBA is blended into the acrylic resin as a nanofiller to prepare the UV-curable nanocomposite. The results indicated that the contact angle of the CNCs increased from 38.7° to approximately 74.8°, and their thermal stability was significantly improved after graft modification. This contributed to the effective alleviation of the agglomeration phenomenon of nanocomposites due to the high hydrophilicity of pure CNCs. Notably, not only was the UV curing efficiency of the nanocomposites greatly increased but the mechanical properties were also further enhanced. Specifically, with the addition of 0.5 wt% CNC-g-PtBA, the curing time of the nanocomposite was shortened from >30 mins down to approximately 6 mins, and the bending strength was increased from 10 MPa for the original resin and 5 MPa for the addition of pure CNCs to 14.3 MPa, and the bending modulus was also greatly increased (up to approximately 730 MPa). Compared to pure CNCs, they are compatible with the resin, exhibiting high mechanical strength and flexibility, and have virtually no effect on the light transmission of the nanocomposites. Additionally, dielectric analysis (DEA) was used to monitor the dielectric constant and conductivity of the UV-curable nanocomposites in real time to further characterize their curing kinetics. The permittivity of these nanocomposites increased by 125 % compared to pristine resin, which shows potential for applications in high dielectric composites or for improving electrical conductivity. This work provides a feasible method for preparing UV-curable nanocomposites with high curing efficiency and permittivity, realizing a wider application of this high-performance nanocomposite.

Synthesis and Characterization of ABA-Type Triblock Copolymers Using Novel Bifunctional PS, PMMA, and PCL Macroinitiators Bearing p-xylene-bis(2-mercaptoethyloxy) Core.

Syntheses of novel bifunctional poly(methyl methacrylate) (PMMA)-, poly(styrene) (PS)-, and (poly ε-caprolactone) (PCL)-based atom transfer radical polymerization (ATRP) macroinitiators derived from p-xylene-bis(1-hydroxy-3-thia-propanoloxy) core were carried out to obtain ABA-type block copolymers. Firstly, a novel bifunctional ATRP initiator, 1,4-phenylenebis(methylene-thioethane-2,1-diyl)bis(2-bromo-2-methylpropanoat) (PXTBR), synthesized the reaction of p-xylene-bis(1-hydroxy-3-thia-propane) (PXTOH) with α-bromoisobutryl bromide. The PMMA and PS macroinitiators were prepared by ATRP of methyl methacrylate (MMA) and styrene (S) as monomers using (PXTBR) as the initiator and copper(I) bromide/N,N,N',N″,N″-pentamethyldiethylenetriamine (CuBr/PMDETA) as a catalyst system. Secondly, di(α-bromoester) end-functionalized PCL-based ATRP macronitiator (PXTPCLBr) was prepared by esterification of hydroxyl end groups of PCL-diol (PXTPCLOH) synthesized by Sn(Oct)2-catalyzed ring opening polymerization (ROP) of ε-CL in bulk using (PXTOH) as initiator. Finally, ABA-type block copolymers, PXT(PS-b-PMMA-b-PS), PXT(PMMA-b-PS-b-PMMA), PXT(PS-b-PCL-b-PS), and PXT(PMMA-b-PCL-b-PMMA), were synthesized by ATRP of MMA and S as monomers using PMMA-, PS-, and PCL-based macroinitiators in the presence of CuBr/PMDETA as the catalyst system in toluene or N,N-dimethylformamide (DMF) at different temperatures. In addition, the extraction abilities of PCL and PS were investigated under liquid-liquid phase conditions using heavy metal picrates (Ag+, Cd2+, Cu2+, Hg2+, Pb2+, and Zn2+) as substrates and measuring with UV-Vis the amounts of picrate in the 1,2-dichloroethane phase before and after treatment with the polymers. The extraction affinity of PXTPCL and PXTPS for Hg2+ was found to be highest in the liquid-liquid phase extraction experiments. Characterizations of the molecular structures for synthesized novel initiators, macroinitiators, and the block copolymers were made by spectroscopic (FT-IR, ESI-MS, 1H NMR, 13C NMR), DSC, TGA, chromatographic (GPC), and morphologic SEM.

Tough and strong sustainable thermoplastic elastomers nanocomposite with self-assembly of SI-ATRP modified cellulose nanofibers.

The ingenious design of sustainable thermoplastic elastomers (STPEs) is of great significance for the goal of the sustainable development. However, the preparation of STPEs with good mechanical performance is still complicated and challenging. Herein, to achieve a simple preparation of STPEs with strong mechanical properties, two biobased monomers (tetrahydrofurfuryl methacrylate (THFMA) and lauryl methacrylate (LMA)) were copolymerized into poly (THFMA-co-LMA) (PTL) and grafted onto TEMPO oxidized cellulose nanofiber (TOCN) via one-pot surface-initiated atom transfer radical polymerization (SI ATRP). The grafting modified TOCN could be self-assembled into nano-enhanced phases in STPEs, which are conducive to the double enhancement of the strength and toughness of the STPEs, and the size of nano-enhanced phases is mainly affected by TOCN fiber length and molecular weight of grafting chains. Especially, with the addition of 7 wt% TOCN, tensile strength, tensile strain, toughness, and glass transition temperature (Tg) of TOCN based STPEs (TOCN@PTL) exhibited 140 %, 36 %, 215 %, and 6.8 °C increase respectively, which confirmed the leading level in the field of bio-based elastomers. In general, this work constitutes a proof for the chemical modification and self-assembly behavior of TOCN by one-pot SI ATRP, and provides an alternative strategy for the preparation of high-performance STPEs.

Tribochemically Controlled Atom Transfer Radical Polymerization Enabled by Contact Electrification.

Traditional mechanochemically controlled reversible-deactivation radical polymerization (RDRP) utilizes ultrasound or ball milling to regenerate activators, which induce side reactions because of the high-energy and high-frequency stimuli. Here, we propose a facile approach for tribochemically controlled atom transfer radical polymerization (tribo-ATRP) that relies on contact-electro-catalysis (CEC) between titanium oxide (TiO2 ) particles and CuBr2 /tris(2-pyridylmethylamine (TPMA), without any high-energy input. Under the friction induced by stirring, the TiO2 particles are electrified, continuously reducing CuBr2 /TPMA into CuBr/TPMA, thereby conversing alkyl halides into active radicals to start ATRP. In addition, the effect of friction on the reaction was elucidated by theoretical simulation. The results indicated that increasing the frequency could reduce the energy barrier for the electron transfer from TiO2 particles to CuBr2 /TPMA. In this study, the design of tribo-ATRP was successfully achieved, enabling CEC (ca. 10 Hz) access to a variety of polymers with predetermined molecular weights, low dispersity, and high chain-end fidelity.

Supramolecular Polymer Brushes Grown by Surface-Initiated Atom Transfer Radical Polymerization from Cucurbit[7]uril-based Non-Covalent Initiators.

Polymer brushes are densely grafted, chain end-tethered assemblies of polymers that can be produced via surface-initiated polymerization. Typically, this is accomplished using initiators or chain transfer agents that are covalently attached to the substrate. This manuscript reports an alternative route towards polymer brushes, which involves the use of non-covalent cucurbit[7]uril-adamantane host-guest interactions to surface-immobilize initiators for atom transfer radical polymerization. These non-covalent initiators can be used for the surface-initiated atom transfer radical polymerization of a variety of water-soluble methacrylate monomers to generate supramolecular polymer brushes with film thicknesses of more than 100 nm. The non-covalent nature of the initiator also allows facile access to patterned polymer brushes, which can be produced in straightforward fashion by drop-casting a solution of the initiator-modified guest molecules onto a substrate that presents the cucurbit[7]uril host.