Atom Transfer Radical Copolymerization Research Articles

Thermally reprocessable bio-based polyhydroxyurethane vitrimers

Vitrimers present one way to address growing demand for sustainably sourced, recyclable thermoset polyhydroxyurethanes (PHUs). We employ vinylogous urethane formation for dynamic bonding, using amine-terminated bio-sourced PHUs (prepared via terpolymerization of diglycerol dicarbonate (DGC) with Priamine 1074 and 1,10-diaminodecane (DAD)) as crosslinkers with ketone-functional copolymers. The latter are synthesized via atom transfer radical copolymerization (ATRP) of an alkyl methacrylate (C13MA, with average side-chain length of 13 carbons) with (2-acetoacetoxy) ethyl methacrylate (AAEMA) (initial AAEMA mole fraction = 0.1–0.4). By manipulating copolymer functionality, thermoset PHUs (Young's moduli spanning from 31 ± 1.5 kPa to 133 ± 5.7 kPa) are obtained. Furthermore, as ketone group concentration increases, networks became tighter, with slower relaxation rates and increased apparent activation energy of stress relaxation, in agreement with calculated molecular weight between crosslinks obtained rheologically. Finally, thermoset PHUs can be effectively recycled three times through remolding at 100 °C without compromising their mechanical properties.

Measurement of the Adhesion Force of a Living Sessile Organism on Antifouling Coating Surfaces Prepared with Polysulfobetaine-Grafted Particles.

An antifouling polymer brush-like structure was fabricated by a simple and versatile dip-coating method of sulfobetaine containing copolymer-grafted silica nanoparticles (SiNPs) and alkyl diiodide cross-linkers. Surface-initiated atom transfer radical copolymerization of 3-(N-2-methacryloyloxyethyl-N,N-dimethyl)ammonatopropanesulfonate (MAPS) and N,N-dimethylaminoethyl methacrylate (DMAEMA) was carried out from initiator-immobilized SiNPs to give poly(MAPS-co-DMAEMA)-grafted SiNPs (MAPS/DMAEMA = 9/1, mol/mol) with diameters of 150-170 nm. The SiNP-g-copolymer/2,2,2-trifluoroethanol solution was dip-coated on silicon and glass substrates. Successive treatment with 1,4-diiodobutane in methanol gave a hydrophilic cross-linked coating film for the SiNP-g-copolymer. The cross-linked particle brushes did not peel off from the substrate even after washing with water in an ultrasonic cleaner despite the simple physical absorption of the SiNP-g-copolymer on the substrate surface. The adhesion force of the tentacle of a living barnacle cyprid on a glass surface covered with the cross-linked SiNP-g-copolymer was directly measured by scanning probe microscopy in seawater. The coating film exhibited extremely low adhesion to the cypris larva in the seawater, expecting this to be an effective antifouling property.

Study on Temperature-Controlled Branching Behavior with Self-Condensing Atom Transfer Radical Copolymerization of Latent Inimer and Styrene

Study on Temperature-Controlled Branching Behavior with Self-Condensing Atom Transfer Radical Copolymerization of Latent Inimer and Styrene

Polyacrylic Acid Copolymers as Adhesion‐Adapted Model Materials for Cleaning Tests

AbstractFor cleaning tests, which are important in many industrial processes, there are no test contaminations with which geometry‐independent homogeneous films can be produced. Polymer films can fill this gap when they are able to mimic the properties of reference contaminants. For this purpose, acrylic acid (AA) copolymers are prepared by conventional atom transfer radical copolymerization and subsequent acidolysis of the tert‐butyl acrylate (tBA) prepolymers. In this way polarity and adhesion can be adjusted by the amount of carboxy groups in the polymer. Dynamic contact angle measurements show that the advancing contact angle of acrylic acid/methyl(meth)acrylate statistical copolymer layers increase with decreasing carboxy group content. Cleaning experiments show accordingly that the amount of residual polymer of coatings made from these polymers is dependent on the absolute number of adhesive carboxy groups in the polymer. Therefore, for an adaption of the polymer layers to hydrophilic reference contaminants it is necessary to incorporate additional hydrophilic monomer components into the polymers, which lead to lower contact angles but also stronger adhesion of the layers. Hence, it is shown that the chosen polymer concept is delivering the leverages to adjust the properties of appropriate test contaminants.

Alternating Methyl Methacrylate/n-Butyl Acrylate Copolymer Prepared by Atom Transfer Radical Polymerization.

Poly(methyl methacrylate/n-butyl acrylate) [P(MMA/BA)] copolymer with an alternating structure was synthesized via an activator regenerated by electron transfer (ARGET) atom transfer radical (co)polymerization (ATRP) of 2-ethylfenchyl methacrylate (EFMA) and n-butyl acrylate (BA) with subsequent postpolymerization modifications (PPM). Due to the steric hindrance of the bulky pendant group of EFMA, as well as the low reactivity ratio of BA in copolymerization with methacrylates, copolymerization of EFMA and BA generated a copolymer with a high content of alternating dyads. A subsequent PPM procedure of the alternating EFMA/BA copolymer was comprised of the hydrolysis of a tertiary ester by trifluoroacetic acid and methylation by (trimethylsilyl)diazomethane. After the modifications, the architecture of the obtained alternating MMA/BA copolymers was compared with gradient and statistical copolymers with overall similar compositions, molecular weights, and dispersities. 13C NMR indicated the absence of either MMA/MMA/MMA or BA/BA/BA sequences, in contrast to an abundance of homotriads in either the statistical or especially in the gradient copolymer. All three copolymers had similar glass transition temperatures, as measured by differential scanning calorimetry (DSC), but the alternating copolymer had the narrowest range of glass transition.

Ultraviolet-cured p-phenylenediamine functionalized polypropylene film as a non-migratory antioxidant

Ultraviolet (UV) induced modification is a simple technique to render the interface of inert materials into a functional property. In this study, a curable copolymer coating was synthesized using glycidyl methacrylate and 4–benzoylphenyl methacrylate via atom transfer radical copolymerization. Butyl acrylate was also introduced to the copolymer, which in turn improved the ductility and facilitated the surface modification using copolymer with bulky groups. The chemical structure of this copolymer was identified using 1H NMR and FTIR. Accordingly, the monomers in the feed were also observed in the copolymer backbone. Ultraviolet (UV) cure potency of the copolymer was monitored using UV–visible spectroscopy in which 90 s UV–irradiation (365 nm) enabled one-step functionalization of polypropylene (PP) surface. Additionally, the existence of the pendant oxirane ring of copolymer on the PP surface after coating assisted in the immobilization of p–phenylenediamine, which realized antioxidant film. The oxidation and reduction abilities of the antioxidant film were assessed using cyclic voltammetry, supporting the free radical scavenging ability of the film. This antioxidant film remarkably (p < 0.05) delayed the lag time of vitamin C degradation and olive oil oxidation. Moreover, the antioxidant film did not leave any migrant behind after incubation with simulant solvents, showing a non-migratory feature. Therefore, this non-migratory antioxidant film can be practically applied in packaging, cosmetic, and biomedical fields.

MOF modified with copolymers containing carboxyl and amidoxime groups and high efficiency U (VI) extraction from seawater

Nuclear energy can effectively alleviate the carbon emission problem caused by fossil fuels. Herein, a highly effective uranium adsorbent MIL-101-SMA-AO modified with carboxyl and amidoxime groups was prepared by a surface-initiated atom transfer radical copolymerization (ATRP) of styrene and maleic anhydride on MIL-101 (Cr) and the subsequent amidoximation. MIL-101-SMA-AO shows ultra-high BET specific surface area (greater than1300 m2∙g−1) and high efficiency adsorption performance, the maximum uranium adsorption capacity reached 1086 mg·g−1. It also shows high selectivity for U (VI) in a simulated seawater and excellent recyclability, the uranium adsorption capacity slightly dropped after five adsorption/desorption cycles. The affecting factors of uranium adsorption process were investigated by batch adsorption experiments under different adsorption conditions. Besides, the results of adsorption kinetics and thermodynamics show that the adsorption process of MIL-101-SMA-AO on U (VI) is controlled by chemical rate and is monolayer adsorption. The synergistic effect of carboxyl and amidoxime groups on the strong chelation with uranium were thought to afford the adsorbent high adsorption property and selectivity for uranium. MIL-101-SMA-AO provides a valid and promising program for the study of uranium extraction from seawater.

Novel antifouling polymer with self-cleaning efficiency as surface coating for protein analysis by electrophoresis

The non-specific adsorption of protein has caused many problems in the application of materials. In this paper, a tri-block copolymer PEO-PNIPAAm-PSPMAP with double effects were obtained via atom transfer radical copolymerization (ATRP). The double-effect copolymer is covalently bonded to the hydrophobic material through a photosensitizer to achieve surface modification and applied to analytical chemistry. Sufficient hydratable groups (for instance, ether bonds, amide groups, and sulfonic acid groups) in the copolymer provides a basis for the anti-protein adsorption. At the same time, the interaction of the hydrophilic group and isopropyl group with temperature changes provides the possibility of elastic self-cleaning of the material, which is instrumental in extending the circulate lifetime of materials. Therefore, it is an environmentally friendly coating material. Besides, the effective antifouling performance and elastic self-cleaning function of the coating have been confirmed by the dynamic adsorption experiment of a fluorescent protein. The coating is used in capillary electrophoresis (CE), and its excellent protein separation spectrum verifies the practicality of the coating.

Kinetics and thermal studies for the copolymerization of styrene and methyl methacrylate by incorporation of mesoporous diatomite

AbstractActivators generated by electron transfer (AGET) for atom transfer radical copolymerization (ATRP) was employed to synthesize tailor‐made random poly (styrene‐co‐methyl methacrylate)/mesoporous kieselgur nanocomposites. Some inherent features of the mesoporous kieselgur platelets were studied by nitrogen adsorption/desorption isotherm and transmission electron microscopy images. Conversion and molecular weight determinations were carried out using gas chromatography and size exclusion chromatography respectively. Addition of 3 wt.% mesoporous kieselgur platelets results in increments of conversion from 72 % to 87 % and molecular weight of copolymer chains from 15986 g mol−1 to 18564 g mol−1 respectively; however, polydispersity index values increases from 1.19 to 1.48. Increasing thermal stability of the nanocomposites is demonstrated by thermogravimetric analysis. Differential scanning calorimetry shows an increase in glass transition temperature from 70.6 °C to 75.7 °C by adding 3 wt.% of mesoporous kieselgur platelets.

Effect of HMDS-modified silica aerogel nanoparticles on ATRP of styrene and methyl methacrylate: Kinetics and thermal studies

Surface of pristine silica aerogel nanoparticles was hydrophobically modified with hexamethyldisilazane (HMDS). Then, the resultant modified nanoparticles were used for in situ atom transfer radical copolymerization of styrene and methyl methacrylate. Surface area and structural characteristics of the HMDS-modified silica aerogel nanoparticles (H-SANs) were examined by nitrogen adsorption/desorption isotherm. Evaluation of size distribution and morphological studies were also performed by scanning electron microscopy and transmission electron microscopy. Conversion and molecular weight determinations were carried out using gas chromatography and size exclusion chromatography, respectively. Adding of H-SAN by 3 wt% results in decrement of conversion from 98% to 79%. In addition, molecular weight of copolymer chains decreases from 20,372 g·mol−1 to 16,487 g·mol−1. However, polydispersity index values increases from 1.38 to 1.76. Linear increase of ln( M0/ M) with time for all the samples shows that polymerization proceeds in a living manner. Increasing thermal stability of the nanocomposites is demonstrated by thermal gravimetric analysis. Differential scanning calorimetry shows a decrease in glass transition temperature from 67.4°C to 59.8°C by the addition of 3 wt% of the H-SAN.

Synthesis of lauryl methacrylate and poly(ethylene glycol) methyl ether methacrylate copolymers with tunable microstructure and emulsifying properties

In this work we study the synthesis and properties of copolymers constituted of lauryl methacrylate and poly(ethylene glycol) methyl ether methacrylate monomers, prepared by atom transfer radical copolymerization in the entire composition range (with low and high monomer conversion). We propose a description of the copolymer microstructure, and evaluate the composition drift effect in the thermal and solution properties of the obtained copolymers. Nuclear magnetic resonance (NMR) was used to determine the chemical composition of the copolymers, while differential scanning calorimetry and themogravimetric analysis was employed to understand the thermal chracteristics. Rheological studies were conducted to obtain the viscosity and viscoelastic properties that were correlated with thermal transitions at different temperatures. Finally, dynamic light scattering (DLS) and surface tension measurements were used to evaluate the copolymer solution properties. The incorporation of an oil phase in the self-assembled aggregates was evaluated by DLS and characterized by atomic force microscopy, diffusion-ordered spectroscopy NMR and nuclear Overhauser effect NMR spectroscopy. Our results suggest a longer sequence of LMA units in the copolymer chain and a drift effect in the case of high monomer conversions. A clear dependence on copolymer composition and microstructure to disperse an oil phase in water was observed. We believe that these results bring valuable knowledge that advances the field of macrosurfactants as well as their potential applications in oil recovery and other industrial processes.

A Study on the Properties of Poly (Styrene-co-Methyl Methacrylate)/Silica Aerogel Nanocomposites Prepared via in situ SR&amp;NI ATRP

Simultaneous reverse and normal initiation technique for atom transfer radical copolymerization (SR&NI ATRP) of styrene and methyl methacrylate in the presence of hexamethyldisilazane (HMDS)-modified silica aerogel nanoparticles (H-SAN) and investigating the effect of addition of H-SAN on the copolymerization and thermal properties of the products are discussed. Some unique features of the H-SAN are evaluated using nitrogen adsorption/desorption isotherm, SEM and TEM. Conversion and molecular weight determinations were carried out using GC and SEC respectively. Adding of H-SAN by 3 wt% results in decrement of conversion from 94 to 73%. In addition, molecular weight of copolymer chains decreases from 19500 to 16000 g.mol-1. However, polydispersity index values increases from 1.29 to 1.65. Linear increase of ln(M0/M) with time for all the samples shows that copolymerization proceeds in a living manner. Increasing thermal stability of the nanocomposites is demonstrated by TGA. DSC results show a decrease in glass transition temperature from 70.3 to 63.5 °C by addition of 3 wt% H-SAN.

Universal Soluble Polymer Supports with Precisely Controlled Loading Capacity for Sequence‐Defined Oligomer Synthesis

ABSTRACTSoluble supports, with optimal molecular structures for iterative oligomer synthesis, were prepared by atom transfer radical copolymerization of styrene with Fmoc‐amino ethyl methacrylate. Size exclusion chromatography and nuclear magnetic resonance indicated formation of copolymers with controlled chain lengths, chain ends, dispersity, and comonomer compositions. These polymers were afterward subjected to two subsequent modifications steps: (a) the debromination of their ω‐chain ends via a tributyltin hydride treatment and (b) the removal of the Fmoc‐protecting groups in acidic conditions, thus leading to bromine‐free copolymers with a precise primary amine loading capacity. These universal amine‐containing precursors were then derived into a variety of functional supports. A glycine‐loaded Wang‐type soluble polystyrene support was prepared in two steps and tested for peptide synthesis as well as for the preparation of digital oligo(alkoxyamine amide)s. In both cases, it was possible to obtain uniform sequence‐defined oligomers as evidenced by electrospray ionization tandem mass spectrometry. However, each type of oligomer required specific experimental conditions and therefore soluble supports with an adapted loading capacity for optimal synthesis. Furthermore, the amine‐containing universal precursors were also transformed into soluble supports for iterative phosphoramidite chemistry. A support was specifically conceived for the iterative synthesis of abiotic digital oligo(phosphodiester)s and another one was designed for oligonucleotide synthesis. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 403–410

Pseudo-Homopolymerization Approach To Predict the Molecular Weight Distribution in the Copolymerization via Activator Regenerated by Electron Transfer Atom Transfer Radical Polymerization

An efficient kinetic model based on the pseudo-homopolymerization (PHP) and reduced stiffness by quasi-steady state approximation (RQSSA) methodology is presented to compute the molecular weight distribution (MWD) in the activator regenerated by electron transfer via atom transfer radical copolymerization. The copolymerization of butyl methacrylate and butyl acrylate is taken as basis of the study; validation with the experimental data results in good agreement, and a deviation between the prediction of the Mayo–Lewis equation and the model estimation is presented. The MWD is dependent on the fed monomer composition. A semibatch process with an extra addition of reduced agent resulted in an increased polymerization rate; however, this affects the process control, and a broader MWD is obtained. The computational time expended to compute the MWD is on the order of seconds or minutes, which can be reduced by using a new expression to calculate the bounds of the MWD.

The impacts of feed fraction on copolymer microstructure in ATRcP: a kinetic Monte Carlo simulation

A research has been carried out to simulate an atom transfer radical copolymerization (ATRcP) system of styrene and n-butyl acrylate using the stochastic Monte Carlo method and to investigate the variation of reactant concentration, average molecular weight and molecular weight distribution, average sequence length and sequence length distribution, different dyad fractions and copolymer composition as a function of styrene feed fraction. To this end, a finely tuned program was written in C++ language to implement the simulation algorithm. It was observed that although styrene feed fraction alteration affected all the factors under review, weight-average molecular weight showed the least variation in its trend for styrene fractions higher than 5%. Finally, the outputs of the current work can be effectively used in tuning and controlling the topology and microstructure of copolymer chains.

Synthesis of poly(ethyl methacrylate-co-methyl methacrylate) obtained via ATRP using ruthenium benzylidene complexes

Abstract Atom-Transfer Radical Copolymerization (ATRP) of methyl methacrylate (MMA) and ethyl methacrylate (EMA) under different reaction conditions was conducted using Grubbs 1st ( 1) and 2nd (2) generation catalysts. Initially, the study focused on the reactivity of the catalysts in ATRP of EMA individually, then the syntheses of poly(MMA-co-EMA) were also conducted in different mixtures of monomers ([MMA]/[EMA] = 100/200 and [MMA]/[EMA] = 200/100). Conversion and semilogarithmic kinetic plots as a function of time were related to the different catalysts and reaction conditions. The values of Mn and PDI also changed when different catalysts were used in the presence of Al(OiPr)3, and more controlled polymerizations were achieved using 1. In the syntheses of poly(MMA)-co -(EMA), conversion of 60% was reached for both catalysts at different [MMA]/[EMA] ratios for 16 h; however, for shorter time, 4 h, better conversion values were obtained using 1 as catalyst for both [MMA]/[EMA] = 100/200 or 200/100.

A Facile Approach towards Fluorescent Nanogels with AIE-Active Spacers.

A facile and efficient approach for design and synthesis of organic fluorescent nanogels has been developed by using a pre-synthesized polymeric precursor. This strategy is achieved by two key steps: (i) precise synthesis of core–shell star-shaped block copolymers with crosslinkable AIEgen-precursor (AIEgen: aggregation induced emission luminogen) as pending groups on the inner blocks; (ii) gelation of the inner blocks by coupling the AIEgen-precursor moieties to generate AIE-active spacers, and thus, fluorescent nanogel. By using this strategy, a series of star-shaped block copolymers with benzophenone groups pending on the inner blocks were synthesized by grafting from a hexafunctional initiator through atom transfer radical copolymerization (ATRP) of 4-benzoylphenyl methacrylate (BPMA) or 2-(4-benzoylphenoxy)ethyl methacrylate (BPOEMA) with methyl methacrylate (MMA) and tert-butyldimethylsilyl-protected 2-hydroxyethyl methacrylate (ProHEMA) followed by a sequential ATRP to grow PMMA or PProHEMA. The pendent benzophenone groups were coupled by McMurry reaction to generate tetraphenylethylene (TPE) groups which served as AIE-active spacers, affording a fluorescent nanogel. The nanogel showed strong emission not only at aggregated state but also in dilute solution due to the strongly restricted inter- and intramolecular movement of TPE moiety in the crosslinked polymeric network. The nanogel has been used as a fluorescent macromolecular additive to fabricate fluorescent film.

In Silico Tracking of Individual Species Accelerating Progress in Macromolecular Engineering and Design.

The beneficial use of computer simulations to track the microstructural evolution of individual species is highlighted in view of macromolecular engineering and design, considering two case studies on catalytic polymerization, and both "low" (<100) and "high" (>100) chain lengths, that is, i) atom transfer radical copolymerization of n-butyl acrylate and styrene aiming at the synthesis of functional macrospecies of "identical' chain length; and ii) chain shuttling polymerization of ethylene and 1-octene toward the production of segmented block copolymers with "soft" and "hard" segments. Model parameters are validated and/or tuned based on literature data. The modeling strategy supports the future identification of chemical structure-polymer property relationships and is based on the combination of principles from polymer reaction engineering, chemistry, and physics.

Ultraviolet light-, temperature- and pH-responsive fluorescent sensors based on cellulose nanocrystals

Intelligent CNC-g-P(AzoC6MA-co-DMAEMA) fluorescent nanosensors present ultraviolet light-, temperature- and pH-responsive properties.

Gradient helical copolymers: synthesis, chiroptical properties, thermotropic liquid crystallinity, and self-assembly in selective organic solvents

A series of novel gradient copolymers R-(−)-poly(StN-grad-C8) were synthesized through atom transfer radical copolymerization of an achiral styrenic monomer, N,N-dimethyl-4-ethenylbenzamide (M-StN), and a chiral bulky vinylterphenyl monomer, (−)-2,5-bis{4′-[(R)-sec-octyloxycarbonyl]phenyl}styrene (R-(−)-M-C8).