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Photochromic and long-lasting photoluminescent transparent, rigid, ultraviolet (UV) protective and superhydrophobic poly(methyl methacrylate) (PMMA) plastic able to switch colour beneath UV irradiation was developed. Photoluminescent transparent PMMA plastic was prepared by the simple polymerization process of methyl methacrylate immobilized with alkaline earth aluminate (AEA) nanoparticles. These colourless PMMA plastic substrates showed a colour switch to greenish underneath UV light as proved using CIELAB screening. The morphology of AEA was evaluated using transmission electron microscopy. Conversely, transparent PMMA samples were evaluated using energy-dispersive X-ray spectra, scanning electron microscope, X-ray fluorescence spectroscopy and for hardness properties. Additionally, the photoluminescence properties were explored by studying excitation and emission spectra. The produced luminescence colourless PMMA plastic substrates displayed excitation band at 370 nm, and three emission peaks at 433, 494 and 513 nm. Photoluminescent PMMA with lower contents of AEA showed fast and reversible photochromism under UV light, while PMMA samples with higher contents of AEA showed long-lasting luminescence such as a flashlight with the ability to replace electric power. The findings showed that the produced photoluminescence colourless PMMA plastic substrates exhibited enhanced UV shielding and superhydrophobicity.

International audience; Two scalable polymerisation methods are used in combination for the synthesis of ethylene and methacrylate block copolymers. w-Unsaturated methacrylic oligomers (MMA n) produced by catalytic chain transfer (co)polymerisation (CCTP) of methyl methacrylate (MMA) and methacrylic acid (MAA) are used as reagents in the radical polymerisation of ethylene (E) in dimethyl carbonate solvent under relatively mild conditions (80 bar, 70 8C). Kinetic measurements and analyses of the produced copolymers by size exclusion chromatography (SEC) and a combination of nuclear magnetic resonance (NMR) techniques indicate that MMA n is involved in a degradative chain transfer process resulting in the formation of (MMA) n-b-PE block copolymers. Molecular modelling performed by DFT supports the overall reactivity scheme and observed selectivities. The effect of MMA n molar mass and composition is also studied. The block copolymers were characterised by differential scanning calorimetry (DSC) and their bulk behaviour studied by SAXS/WAXS analysis.

In this contribution, Lewis pairs (LPs) composed of N-heterocyclic olefins (NHOs) with different steric hindrance and nucleophilicity as Lewis bases (LBs) and Al-based compounds with comparable acidity but different steric hindrance as Lewis acids (LAs) were applied for 1,4-selective polymerization of (E,E)-methyl sorbate (MS) and (E,E)-ethyl sorbate (ES). The effects of steric hindrance, electron-donating ability, and acidity of LPs on MS and ES polymerization were systematically investigated. High catalytic activity and high initiation efficiency can be achieved, leading to the formation of PMS with 100 % 1,4-selectivity, tunable molecular weight (Mw up to 333 kg mol-1 ), and narrow molecular weight distribution (MWD). Block copolymerization of ES and methyl methacrylate (MMA) was also realized. Meanwhile, this system can be applied to other homologous conjugated diene substrates. Furthermore, simple chemical reactions can efficiently convert PMS to different polymers with strict (AB)n sequence structures, such as poly(sorbic acid), poly(propylene-alt-methyl acrylate), poly(propylene-alt-acrylic acid), poly(propylene-alt-allyl alcohol), and poly(ethylene-alt-2-butylene).

In our previous work [Edeleva et al. Chem. Commun. 2019, 55, 190-193], we proposed a versatile approach to the activation of the homolysis of an aldonitrone group-containing alkoxyamine by 1,3-dipolar cycloaddition to a vinyl monomer. Both nitroxide- and alkoxyamine-containing aldonitrones were found to be capable of reacting with the activated alkenes. In the present study, the kinetics of these reactions with 11 different vinyl monomers were investigated using EPR and NMR spectroscopy, and apparent activation energies as well as pre-exponential factors were determined. The influence of monomer structure on the rate of the 1,3-dipolar cycloaddition is discussed. For the vinyl monomers typically used in nitroxide mediated polymerization (styrene, methyl methacrylate) the rate coefficient of cycloaddition to the nitroxide is around k(353 K) ∼4 ⋅ 10-4 L mol-1 s-1 , whereas for n-butyl acrylate and methyl vinyl ketone we observed the fastest cycloaddition reaction with k(353 K)=8 ⋅ 10-3 and 4 ⋅ 10-2 L mol-1 s-1 respectively.

Without solvents present, the often far-from-equilibrium environment in a mechanochemically driven synthesis can generate high-energy, non-stoichiometric products not observed from the same ratio of reagents used in solution. Ball milling 2 equiv. K[A'] (A'=[1,3-(SiMe3 )2 C3 H3 ]- ) with CaI2 yields a non-stoichiometric calciate, K[CaA'3 ], which initially forms a structure (1) likely containing a mixture of pi- and sigma-bound allyl ligands. Dissolved in arenes, the compound rearranges over the course of several days to a structure (2) with only η3 -bound allyl ligands, and that can be crystallized as a coordination polymer. If dissolved in alkanes, however, the rearrangement of 1 to 2 occurs within minutes. The structures of 1 and 2 have been modeled with DFT calculations, and 2 initiates the anionic polymerization of methyl methacrylate and isoprene; for the latter, under the mildest conditions yet reported for a heavy Group 2 species (one-atm pressure and room temperature).

The design and development of organic luminophores that exhibit efficient ultraviolet (UV) fluorescence in the solid state remains underexplored. Here, we report that 1,4-dialkenyl-2,5-dialkoxybenzenes and 1,4-dialkenyl-2,5-disiloxybenzenes act as such UV-emissive fluorophores. The dialkenyldioxybenzenes were readily prepared in three steps from 2,5-dimethoxy-1,4-diacetylbenzene or 2,5-dimethoxy-1,4-diformylbenzene via two to four steps from 1,4-bis(diethoxyphosphonylmethyl)-2,5-dimethoxybenzene. The dialkenyldioxybenzenes emit UV light in solution (λem =350-387 nm) and in the solid state (λem =328-388 nm). In addition, the quantum yields in the solid state were generally higher than those in solution. In particular, the adamantylidene-substituted benzenes fluoresced in the UV region with high quantum yields (Φ=0.37-0.55) in the solid state. Thin films of poly(methyl methacrylate) doped with the adamantylidene-substituted benzenes also exhibited UV emission with good efficiency (Φ=0.27-0.45). Density functional theory calculations revealed that the optical excitation of the dialkenyldimethoxybenzenes involves intramolecular charge-transfer from the ether oxygen atoms to the twisted alkenyl-benzene-alkenyl moiety, whereas the dialkenylbis(triphenylsiloxy)benzenes were optically excited through intramolecular charge-transfer from the oxygen atoms and twisted π-system to the phenyl-Si moieties of each triphenylsilyl group.

Here we report five blue-phosphorescent platinum bis-phenylacetylide complexes with an investigation of their photophysical and electrochemical attributes. Three of the complexes ( 1 - 3 ) are of the general formula cis -Pt(CNR) 2 (C≡CPh) 2 , where CNR is a variably substituted isocyanide and C≡CPh is phenylacetylide. These isocyanide complexes serve as precursors for complexes of the general formula cis -Pt(CNR)(ADC)(C≡CPh) 2 ( 4 and 5 ), where ADC is an acyclic diaminocarbene installed by amine nucleophilic addition to one of the isocyanides. All of the complexes exhibit deep blue phosphorescence with λ max ~430 nm in poly(methyl methacrylate) (PMMA) thin films. Whereas isocyanide complexes 1 - 3 exhibit modest photoluminescence quantum yields ( Φ PL ), incorporation of one acyclic diaminocarbene ligand results in a three-fold to 16-fold increase in Φ PL while still maintaining an identical deep blue color profile.

The present study is focused on the integration of microreactors to synthesize visible light active nanophotocatalysts for inline photocatalytic degradation of organic dye and antibacterial activity. A wire-assisted and a rapid laser micromachining technique has been employed for the fabrication of polydimethylsiloxane (PDMS) and poly(methyl methacrylate) (PMMA)-based microreactors, respectively. By varying the design and chemical reagents involved, different sizes of visible light active Ag2 S nanoparticles were prepared via a continuous microfluidics approach using fabricated microreactors. When polyvinylpyrrolidone (PVP) was utilized as the capping agent during the reaction, smaller particles of the size of ~ 15 nm were observed. The photocatalytic performance of these nanoparticles has been evaluated inline by employing the single-inlet planar microreactor as a function of flow rate and channel length. The photocatalyst durability test and a comparative photocatalytic efficiency study between the microreactor and the conventional beaker reactor have also been carried out. Under visible light, these nanoparticles exhibit a remarkable enhancement of ~ 94.5% in the inline microreactor-based photocatalytic degradation of methylene blue dye. The slower the flow rate and longer the channel length, gradual enhancement in the performance has been observed. Also, these nanoparticles express an antibacterial effect with very high efficacy even at very low (2 mg mL-1 ) concentration toward the inhibition of Escherichia Coli.

Milling two equivalents of K[1,3-(SiMe3 )2 C3 H3 ] (=K[A']) with MgX2 (X=Cl, Br) produces the allyl complex [K2 MgA'4 ] (1). Crystals grown from toluene are of the solvated species [((η6 -tol)K)2 MgA'4 ] ([1⋅2(tol)]), a trimetallic monomer with both bridging and terminal (η1 ) allyl ligands. When recrystallized from hexanes, the unsolvated 1 forms a 2D coordination polymer, in which the Mg is surrounded by three allyl ligands. The C-C bond lengths differ by only 0.028 A, indicating virtually complete electron delocalization. This is an unprecedented coordination mode for an allyl ligand bound to Mg. DFT calculations indicate that in isolation, an η3 -allyl configuration on Mg is energetically preferred over the η1 - (σ-bonded) arrangement, but the Mg must be in a low coordination environment for it to be experimentally realized. Methyl methacrylate is effectively polymerized by 1, with activities that are comparable to K[A'] and greater than the homometallic magnesium complex [{MgA'2 }2 ].

Bone cement is used extensively in orthopedics to anchor prostheses to bone and fill voids. Incorporating bioactive glass into poly(methyl methacrylate) (PMMA)-based bone cement could potentially improve its effectiveness for these tasks. This study characterizes the mechanical and degradation properties of composites containing PMMA-based bone cement and particles of borate bioactive glass designated as 13-93B3. Glass particles of size 5, 33, and 100 μm were mixed with PMMA bone cement to create composites containing 20, 30, and 40 wt % glass. Composites and a bone cement control were soaked in phosphate-buffered saline. Compressive strength, Young's modulus, weight loss, water uptake, solution pH, and ionic concentrations were measured over 21 days. The compressive strengths of composites decreased over 21 days. Average Young's moduli of the composites remained below 3 GPa. Weight loss and water uptake of specimens did not exceed 2 and 6%, respectively. Boron concentrations and pH of all solutions increased over time, with higher glass weight fractions leading to higher pH values. Results demonstrated that the composite can sustain glass degradation and ionic release without compromising short-term mechanical strength.

Fluorescence-phosphorescence dual-emissive compounds are valuable tools for ratiometric luminescence sensing. Herein, it is reported that 2,5-bis(phenylsulfonyl)- and 2,5-bis[bis(4-methoxyphenyl)phosphinyl]-1,4-disiloxybenzenes exhibit dual emission with emission peaks that were easily identified without performing time-gated measurement. The disiloxybenzenes in powder simultaneously fluoresced and phosphoresced at 358-374 and 457-470 nm, respectively, under vacuum. The intensity ratios of the phosphorescence/fluorescence maxima of the disiloxybenzenes in powder and in a thin film of poly(methyl methacrylate) were sensitive to temperature and molecular oxygen, respectively. The plots of the relative intensity versus temperature or partial pressure of molecular oxygen were well fitted with calibration curves defined by an exponential approximation with excellent correlation coefficients R2 (0.9708-0.9921), demonstrating the high potential of the disiloxybenzenes as precious metal-free probes applicable to ratiometric luminescence sensing.

Carbon dots (CDs) have been used for the first time as a sensitizer to initiate and activate free radical and controlled radical polymerization, respectively, based on an ATRP protocol with blue LEDs. Consideration of diverse heteroatom‐doped CDs indicated that N‐doped CDs could serve as an effective photocatalyst and photosensitizer in combination with LEDs emitting either at 405 nm or 470 nm. Free radical polymerization was initiated by combining the CDs with an iodonium or sulfonium salt in tri(propylene glycol) diacrylate. Polymerization of methyl methacrylate (MMA) by photo‐induced ATRP was achieved with CDs and ethyl α‐bromophenylacetate using CuII as catalyst in the ppm range. The polymers obtained showed temporal control, narrower dispersity ≲1.5, and chain‐end fidelity. The first‐order kinetics and ON/OFF experiments additionally gave evidence of the constant concentration of polymer radicals. No remarkable cytotoxic activity was observed for the CDs, underlining their biocompatibility., On the dot: Carbon dots isolated from seaweed work well as a photocatalyst and sensitizer in living and free radical polymerization, while their low cytotoxic activity makes them interesting for medical applications.

The conformation in solution of monocrotaline, a pyrrolizidine alkaloid presenting an eleven-membered macrocyclic diester ring, has been investigated using a combination of isotropic and anisotropic nuclear magnetic resonance parameters measured in four solvents of different polarity (D2 O, DMSO-d6 , CDCl3 , and C6 D6 ). Anisotropic nuclear magnetic resonance parameters were measured in different alignment media, based on their compatibility with the solvent of interest: cromoglycate liquid crystal solution was used for D2 O, whereas a poly (methyl methacrylate) polymer gel was chosen for CDCl3 and C6 D6 , and a poly (hydroxyethyl methacrylate) gel for DMSO-d6 . Whereas the pyrrolizidine ring shows an E6 exo-puckered conformation in all of the solvents, the macrocyclic eleven-membered ring adopts different populations of syn-parallel and anti-parallel relative orientation of the carbonyl groups according to the polarity of the solvent.

Polymers having polyhedral oligomeric silsesquioxane (POSS) in the main chains are an important class of organic–inorganic hybrid materials. Despite the increasing attention to the POSS polymers, variation of the monomers is still limited. Herein, we have proposed side‐opening POSS (SO‐POSS) monomers. Platinum‐catalyzed hydrosilylation polymerization proceeded to produce polysiloxanes having SO‐POSS in the main chains. The obtained polysiloxanes showed good solubility, high thermal stability, high transparency, and tunable reflective index. In addition, cyclic compounds were obtained during the investigation of the polymerization, and were synthesized with high selectivity under the slightly diluted conditions. The obtained cyclic compounds showed high thermal stability due to the silsesquioxane backbone, and the high dispersibility as a filler in poly(methyl methacrylate) was demonstrated. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2243–2250

The technique for synthesis of poly (methyl methacrylate) by atom transfer radical polymerization has been strengthened by using graphene nanoplatelets to enhance the elastic properties of the polymer. In order to improve practical, economical and mechanical performance, the requirements for effective implementation of production control as a smart bulk polymer nanocomposite were determined for cost-effective bulk production. Three-dimensional inspection (using an ultrasound interrogation method for the whole volume under test) confirmed the synthesis of the nanocomposite to be free of agglomeration and bubbles. As a result of this elimination of defects, an enhancement in compressive strength of 42.7% was achieved and the Rockwell hardness was increased by 19.9 % through the addition of graphene nanoplatelets at 2 wt% by mass. The deformation and mechanical failure properties have been characterised in the mechanical enhancement of the polymer nanocomposite. Elastic parameters determined using ultrasound testing identified that changes in the structural features following the addition of these GNPs were uniquely connected to the enhancements in these elastic parameters (such as Young’s modulus, Poisson’s ratio, shear modulus and microhardness) of the poly (methyl methacrylate) / graphene nanoplatelets nanocomposite.

Aldehyde groups enable facile conjugation to proteins, enzymes, oligonucleotides or fluorescent dyes, yet there are no literature examples of water‐soluble aldehyde‐functional vinyl monomers. We report the synthesis of a new hydrophilic cis‐diol‐based methacrylic monomer (GEO5MA) by transesterification of isopropylideneglycerol penta(ethylene glycol) using methyl methacrylate followed by acetone deprotection via acid hydrolysis. The corresponding water‐soluble aldehyde monomer, AGEO5MA, is prepared by aqueous periodate oxidation of GEO5MA at 22 °C. RAFT polymerization of GEO5MA yields the water‐soluble homopolymer, PGEO5MA. Aqueous periodate oxidation of the terminal cis‐diol units on PGEO5MA at 22 °C affords a water‐soluble aldehyde‐functional homopolymer (PAGEO5MA). Moreover, a library of hydrophilic statistical copolymers bearing cis‐diol and aldehyde groups was prepared using sub‐stoichiometric periodate/cis‐diol molar ratios. The aldehyde groups on PAGEO5MA homopolymer were reacted in turn with three amino acids to demonstrate synthetic utility., A water‐soluble aldehyde monomer (AGEO5MA) was prepared by oxidation of GEO5MA at 22 °C. RAFT aqueous polymerization yielded PAGEO5MA homopolymer, which was oxidized using sub‐stoichiometric periodate/cis‐diol molar ratios to yield hydrophilic statistical copolymers with cis‐diol and aldehyde groups. Three PGEO5MA‐based diblock copolymers were converted into aldehyde‐functional copolymers, which were derivatized with amino acids.

Poly(methyl methacrylate) (PMMA) nanoparticles with a sensitive CO₂‐responsive hydrophilic/hydrophobic surface that confers controlled dispersion and aggregation in water were prepared by emulsion polymerization at 50 °C under CO₂ bubbling using amphiphilic diblock copolymers of 2‐dimethylaminoethyl methacrylate (DMAEMA) and N‐isopropyl acrylamide (NIPAAm) as an emulsifier. The amphiphilicity of the hydrophobic–hydrophilic diblock copolymer at 50 °C was triggered by CO₂ bubbling in water and enabled the copolymer to serve as an emulsifier. The resulting PMMA nanoparticles were spherical, approximately 100 nm in diameter and exhibited sensitive CO₂/N₂‐responsive dispersion/aggregation in water. Using copolymers with a longer PNIPAAm block length as an emulsifier resulted in smaller particles. A higher concentration of copolymer emulsifier led to particles with a stickier surface. Given its simple preparation and reversible CO₂‐triggered amphiphilic behavior, this newly developed block copolymer emulsifier offers a highly efficient route toward the fabrication of sensitive CO₂‐stimuli responsive polymeric nanoparticle dispersions. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2149–2156

Poly(methyl methacrylate) (PMMA) bone cement is the most widely used grouting material in the joint arthroplasties and vertebroplasties. The present investigation has been carried out to scavenge the radicals and monomer by addition of an antioxidant to minimize the toxicity of bone cement (BC). The in silico studies were employed to determine the potent natural antioxidant at physiological conditions. The antioxidant methionine demonstrated a strong binding affinity with free radicals and methyl methacrylate (MMA) monomer than cysteine. The designated amount of methionine was optimized by various assay methods and >2% methionine shows strong scavenging capacity in BC. Moreover, the antioxidant-loaded BC (ABC) demonstrated similar handling, physicochemical and mechanical properties to pristine bone cement. Significantly, the developed formulation shows superior biological characteristics such as cell proliferation (2 ± 1 BC and 6 ± 1 ABC), adhesion (0.32 ± 0.02 BC and 0.54 ± 0.01 ABC), and cell viability (81 ± 2% BC and 93 ± 1% ABC) toward human osteoblast-like cells (MG-63). Therefore, the novel antioxidant bone cement is a potential candidate for various orthopedic applications to eliminate the adverse effects, related to residual toxic radical and monomer in bone cement.

Methacrylic esters, represented by methyl methacrylate (MMA), are widely used as commodity chemicals. Here, the one-pot synthesis of methacrylic esters from acetone, a haloform and alcohols in the presence of an organic base is described. Using DBU as the organic base for the reaction of acetone, chloroform and methanol in acetonitrile afforded MMA in 66 % yield. When the solvent was replaced by benzonitrile, the product MMA was successfully purified by distillation. Applicability of this process to various alcohols was also investigated to show ethyl, phenyl, CF3 CH2 , and n-C6 F13 CH2 CH2 esters were obtained in moderate yields. The use of bromoform instead of chloroform resulted in the improvement of the yield, for example, methyl and n-C6 F13 CH2 CH2 esters up to 81 and 70 %, respectively. The reaction with deuterated starting materials acetone-d6 and MeOH-d4 , with DBU in acetonitrile afforded deuterated MMA (MMA-d8 ) in 70 % yield.

An approach for preparing highly conductive poly(methyl methacrylate)–reduced graphene oxide (PMMA/rGO) composites by in situ polymerization of methyl methacrylate (MMA) monomer in the presence of iron metal induced deoxygenated rGO is reported. The obtained PMMA/rGO exhibited excellent electrical properties with a percolation threshold as low as 0.1 wt.% and electrical conductivity of 14 S/m at only 0.8 wt.% rGO loading. Moreover, with only 0.4 wt.% rGO content, the glass transition temperature (T) of the prepared PMMA/rGO composite was enhanced by 16°C which corresponds to 17% improvement when compared to that of the neat PMMA. Furthermore, tensile strength increased by 26% as compared to that of the neat PMMA.

Two kinds of Schiff base, N,N′‐dibenzylidene‐1,2‐diaminoethane (NDBE) and N,N′‐disalicylidene‐1,2‐diaminoethane, have been found as efficient organic catalyst for reversible complexation‐mediated radical polymerization (RCMP) of methyl methacrylate (MMA) for the first time. The polymerization results show obvious features of “living”/controlled radical polymerization. Well‐defined and low‐polydispersity polymers (Mw/Mₙ = 1.20–1.40) are obtained in RCMP of MMA catalyzed by Schiff base at mild temperature (65–80°C). Moreover, Schiff base also exhibits a particularly high reactivity for RCMP of MMA with in situ formed alkyl iodide initiator. The polymer molecular weight and its polydispersity (Mw/Mₙ is around 1.20) are well controlled even with high monomer conversion. Notably, when the dosage of azo initiator is same as the dosage of iodine, the polymerization could also be realized in the presence of NDBE. The living feature of synthesized polymer is confirmed through the chain extension experiment. In short, Schiff base is a kind of high‐efficient catalyst for RCMP and reverse RCMP of MMA, which can be one of the most powerful and robust techniques for polymer synthesis. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1653–1663

We carried out a large set of tests to establish a correlation between the molecular (network) structure (influenced by molecular weight, molecular weight distribution, and melt predeformation) and mechanical responses of several glassy polymers to uniaxial compression at different temperatures and different compression speeds. The experimental results show that to have ductile responses there must be an adequate chain network, afforded by the interchain uncrossability among sufficiently long chains. Specifically, polystyrene (PS) and poly(methyl methacrylate) of sufficiently low molar mass do not have chain network and are found to be very brittle. Binary PS mixtures are brittle at room temperature when the volume fraction of the high‐molecular‐weight component is sufficiently low (e.g., at and below 27.5%). Moreover, sufficiently melt‐stretched PS mixtures show brittle fracture when compressed along the same direction, along which melt stretching was made. All the experimental findings confirm that a robust chain network is also a prerequisite for yielding and ductile cold compression of polymer glasses, as is for extension. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 758–770

The decomposition rate constant (kd) of pinacolone diperoxide (PDP, 3,6‐diterbutyl‐3,6‐dimethyl‐1,2,4,5‐tetraoxacyclohexane) in methyl methacrylate (MMA) is determined by the kinetic study of its thermal decomposition at temperatures from 110 °C to 140 °C. The calculated kd values for PDP are higher than the corresponding values previously determined and reported for diethyl ketone triperoxide (DEKTP, 3,3,6,6,9,9‐hexaethyl‐1,2,4,5,7,8‐hexaoxacyclononane), for example, at 140 °C the kd for PDP is 75.4 × 10⁻⁵ s⁻¹, while for DEKTP, it is 50.6 × 10⁻⁵ s⁻¹. The difference in the kd between 130 °C and 140 °C indicates that the decomposition mechanism, sequential and/or concerted, is a function of temperature. The conformations of both initiators justify the higher kd for PDP in MMA than DEKTP, where one single conformer is found for PDP, whereas 212 conformers are found for DEKTP. Bulk polymerization of MMA using PDP as the initiator reveals also the presence of an induction period, such as in DEKTP case. This work provides mechanistic insights into the interactions among the bifunctional cyclic peroxide PDP and the MMA monomer and their influence on the polymerization kinetics. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 997–1007

PURPOSE The objective of this study was to improve the surface characteristics of poly (methyl methacrylate) (PMMA) by developing a novel, thin film coating process and to characterize the resulting coated surface. MATERIALS AND METHODS An atomic layer deposition (ALD) technique was developed to deposit a titanium dioxide (TiO2 ) nano-thin film on PMMA. The surface wettability for both coated and uncoated PMMA was determined by measuring water contact angle. Wear resistance was assessed using a mechanical tooth-brushing device with a 50 g load for 6000 strokes after 5 months of water storage. A denture cleanser challenge test was performed by using sonication in 3.8% sodium perborate for 1 hour with aged specimens. X-ray photoelectron spectroscopy (XPS) was used before and after the brushing test and challenge test to analyze the PMMA surface chemical composition. The mechanical strength of coated and uncoated PMMA was measured using a three-point bending test. Surface microbial interactions were also evaluated by assessing Candida albicans biofilm attachment. RESULTS Nano-TiO2 coating (30 nm thick) was successfully deposited on PMMA at 65°C. After coating, water contact angle decreased from 70° to less than 5°. After brushing test, the coating remained intact. XPS analysis revealed no loss of TiO2 from coated specimens following brushing and denture cleanser sonication for 1 hour. There was no statistically significant difference in mechanical strength (MPa) (mean ± SD) between PMMA (139.4 ± 11.3) and TiO2 -PMMA (160.7 ± 37.1) (p = 0.0995). C. albicans attachment decreased by 63% to 77% on the coated PMMA surface. CONCLUSIONS ALD is a promising technique to modify surface properties of PMMA and resulted in a stable adherent thin film. By depositing a TiO2 coating, PMMA surface properties may lead to significantly reduced microorganism adhesion and easier pathogen removal from PMMA. For patients who wear dentures, reducing the oral microbial biofilm burden using a TiO2 -coated PMMA surface could positively impact their oral and systemic health.

It is demonstrated that the degree of livingness (chain‐end fidelity) in RAFT polymerization for a given degree of polymerization can be markedly increased in miniemulsion polymerization relative to the corresponding homogeneous bulk system. Polymerization of styrene was conducted using a poly(methyl methacrylate) benzodithioate as macroRAFT agent in both miniemulsion and bulk. The substantially higher polymerization rate in miniemulsion, which is attributed to the segregation effect (compartmentalization) causing a reduction in the rate of bimolecular termination, makes it possible to reach a given degree of polymerization in a significantly shorter time than in the corresponding bulk system. As a consequence, fewer initiating radicals are required throughout the polymerization, leading to higher livingness in the more rapid miniemulsion system. It is demonstrated how this approach facilitates synthesis of high‐molecular‐weight block copolymers comprising slowly propagating monomers such as styrene and methacrylates. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1938–1946

We present a systematic study of incorporating carboxyl groups into latex particles to enhance colloidal stability and the physical properties of the latex. Statistical copolymers of methacrylic acid and methyl methacrylate) were synthesized via catalytic chain transfer polymerization (CCTP) in emulsion. The vinyl‐terminated oligomers were in turn successfully utilized as chain transfer agents for the formation of diblock and pseudo triblock copolymers via sulfur‐free reversible addition–fragmentation chain transfer polymerization (SF‐RAFT). These copolymers were characterized using 1H NMR, size exclusion chromatography (SEC), dynamic light scattering (DLS), dynamic mechanical analysis (DMA), contact angle measurements and matrix‐assisted laser desorption/ionization time of flight mass spectroscopy (MALDI‐TOF‐MS) techniques. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019\ud \ud

A detailed computational study of the Diels‐Alder reaction of cyclopentadiene with acrylonitrile, methylacrylate and their α‐methylated counterparts methacrylonitrile and methyl methacrylate at the M06‐2X(PCM)/TZVP level of theory has been performed. We want to understand the excellent exo‐selectivities observed experimentally due the presence of this substituent. To this end, analysis of the reaction coordinate by means of activation strain model of chemical reactivity (ASM‐distortion interaction model) including solvation effects and NBO second order perturbation energy have been carried out.

We prepared dimethyl and diaryl 2,5-dialkoxytere-phthalates from dimethyl 2,5-dihydroxyterephthalate in good-to-high yields via alkylation or a sequence of alkylation, hydrolysis, chlorination, and condensation. The absorption spectra of the dialkoxyterephthalates contain a small band at 332-355 nm, which could be assigned to intramolecular charge-transfer transition from the alkoxy to alkoxycarbonyl groups on the basis of theoretical calculations using density functional theory. The dialkoxyterephthalates exhibited blue fluorescence with moderate-to-excellent quantum yields not only in solution but also in the solid state, such as a poly(methyl methacrylate) (PMMA) film and a powder. The solid-state quantum yields of the diisopropoxy-substituted terephthalates were similar or considerably higher than those of the dimethoxy-substituted counterparts. Copolymerization of 2,5-diisopropoxyterephthaloyl chloride and 1,4-butanediol with or without terephthaloyl chloride gave brilliantly blue fluorescent polymers, whose quantum yields were 0.72 and 0.71 in toluene and 0.46 and 0.40 in the neat film, respectively. Furthermore, white emission was achieved when a fluorescent yellow 2,5-diaminoterephthalate was doped into the thin film of the blue fluorescent polymer at 0.4 wt %.

Although living polymerization methods are widely applicable to organic monomers, their application to inorganic monomers is rare. For the first time, we show that the living poly(methylenephosphine) (PMPn- ) anion can function as a macroinitiator for olefins. Specifically, the phosphaalkene, MesP=CPh2 (PA), and methyl methacrylate (MMA) can be sequentially copolymerized using the BnLi-TMEDA initiator system in toluene. A series of PMPn -b-PMMAm copolymers with narrow dispersities are accessible (Đ=1.05-1.10). Analysis of the block copolymers provided evidence for -P-CPh2 -CH2 -CMe(CO2 Me)- switching groups. Importantly, this indicates that the -P-CPh2- anion directly initiates the anionic polymerization of MMA and stands in stark contrast to the isomerization mechanism followed for the homopolymerization of PA. For the first time, the glass transition of a PMPn homopolymer has been measured (Tg =45.1 °C, n=20). The PMPn -b-PMMAm copolymers do not phase separate and show a single Tg which increases with higher PMMA content.

Vinyl-group-substituted, α-cyclodextrin-based, size-complementary [3]rotaxanes were synthesized as crosslinkers for rotaxane-crosslinked poly(methyl methacrylate) (RCP) by radical polymerization. The size complementarity of the crosslinkers made it possible to de-crosslink the RCP by heating, and the degree of decoupling was monitored by fluorescence intensity, depending on the state of the axle component of the rotaxane crosslink moiety.

This is the peer reviewed version of the following article: Sharifi, S., Islam, M.M., Sharifi, H., Islam, R., Huq, T.N., Nilsson, P.H., ... Chodosh, J. (2021). Electron Beam Sterilization of Poly(Methyl Methacrylate)—Physicochemical and Biological Aspects. Macromolecular Bioscience, 21(4), 2000379, which has been published in final form at https://doi.org/10.1002/mabi.202000379. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited. Electron beam (E-beam) irradiation is an attractive and efficient method for sterilizing clinically implantable medical devices made of natural and/or synthetic materials such as poly(methyl methacrylate) (PMMA). As ionizing irradiation can affect the physicochemical properties of PMMA, understanding the consequences of E-beam sterilization on the intrinsic properties of PMMA is vital for clinical implementation. A detailed assessment of the chemical, optical, mechanical, morphological, and biological properties of medical-grade PMMA after E-beam sterilization at 25 and 50 kiloGray (kGy) is reported. Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry studies indicate that E-beam irradiation has minimal effect on the chemical properties of the PMMA at these doses. While 25 kGy irradiation does not alter the mechanical and optical properties of the PMMA, 50 kGy reduces the flexural strength and transparency by 10% and 2%, respectively. Atomic force microscopy demonstrates that E-beam irradiation reduces the surface roughness of PMMA in a dose dependent manner. Live-Dead, AlamarBlue, immunocytochemistry, and complement activation studies show that E-beam irradiation up to 50 kGy has no adverse effect on the biocompatibility of the PMMA. These findings suggest that E-beam irradiation at 25 kGy may be a safe and efficient alternative for PMMA sterilization.