Tert-butyl Acrylate Research Articles

Synthesis and characterization of easily degradable acrylate-epoxy resin with superior dielectric properties and high transmittance

Thermally degradable thermoset acrylate-epoxy resins with thermal cleavable groups had been prepared by a series of acrylate-epoxy pre-polymers which was cured with 4-methyl hexahydrophthalic anhydride (MHHPA). The acrylate-epoxy pre-polymers were synthesized via the radical polymerization of 3, 4-epoxycyclohexylmethyl methacrylate (EMA) with butyl methacrylate (BMA), tert-butyl methacrylate (TBMA), tert-butyl acrylate (TBA) and butyl acrylate (BA), respectively. The chemical structure of pre-polymers was characterized in detail. The thermal degradation mechanism and thermal properties, mechanical properties as well as dielectric properties of the acrylate-epoxy resins were systematically investigated. Results showed that t-butyl group and methyl group had a positive influence on the main thermal degradation process. TBMA-E/M presented lower degradation temperature (The initial degradation temperature is ~214 °C) and dielectric constant (~3.19 at 106 Hz) among these thermosets. Besides, all samples possessed similar high transmittance in the visible range. Therefore, acrylate-epoxy resins had a promising application and degraded at a desirable temperature.

Aggregation-Induced Emission Active Polyacrylates via Cu-Mediated Reversible Deactivation Radical Polymerization with Bioimaging Applications.

The introduction of aggregation-induced emission (AIE) moieties into polymers results in smart materials with AIE characteristics, expanding their scope of applications. Herein, well-defined polymers with controlled molecular weight, low dispersity, and high end-group fidelity areproducedvia copper(0)-mediated reversible-deactivation radical polymerizations (Cu(0)-RDRPs). An AIE-containing initiator tetraphenylethene bromoisobutyrate (TPEBIB) has been synthesized, fully characterized, and utilized for the construction of different polyacrylate homopolymers and block copolymers bearing the TPE group with a range of molecular weights and architectures. All of the polymers exhibited AIE behavior. Notably, the hydrophobic TPE-poly(tert-butyl acrylate) (TPE-PtBA)-containing block copolymers are transformed to TPE-poly(acrylic acid) (TPE-PAA)-based amphiphilic copolymers by facile deprotection, enabling pH-tunable self-assembly in aqueous media to give fluorescent nanoparticles with various sizes. The low cytotoxicity, high specificity, and excellent photostability render them promising candidates as lysosome-specific probes in biological imaging applications.

Surface Functionalization of Magnetic Nanoparticles Using a Thiol-Based Grafting-Through Approach

Here we describe a simple and straightforward synthesis of different multifunctional magnetic nanoparticles by using surface bound thiol-groups as transfer agents in a free radical polymerization process. The modification includes a first step of surface silanization with (3-mercaptopropyl)trimethoxysilane to obtain thiol-modified nanoparticles, which are further used as a platform for modification with a broad variety of polymers. The silanization was optimized in terms of shell thickness and particle size distribution, and the obtained materials were investigated by dynamic light scattering (DLS), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). Subsequently, the free radical polymerization of different monomers (tert-butyl acrylate (tBA), methyl methacrylate (MMA), styrene, 2-vinyl pyridine (2VP), and N-isopropylacrylamide (NIPAAm)) was examined in the presence of the thiol-modified nanoparticles. During the process, a covalently anchored polymeric shell was formed and the resulting core–shell hybrid materials were analyzed in terms of size (DLS, TEM), shell thickness (TGA, TEM), and the presence of functional groups (attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FT-IR)). Hereby, the shell leads to a different solution behavior of the particles and in some cases an increased stability towards acids. Moreover, we examined the influence of the nanoparticle concentration during polymerization and we found a significant influence on dispersity of the resulting polymers. Finally, we compared the characteristics of the surface bound polymer and polymer formed in solution for the case of polystyrene. The herein presented approach provides straightforward access to a wide range of core–shell nanocomposites.

Thermal property of photonic crystals (PCs) prepared by solvent annealing self-assembly of bottlebrush PS-b-PtBA

One-dimensional photonic crystals (1D PCs) prepared by solvent annealing self-assembly of bottlebrush block copolymers have attracted much attention due to their low cost and convenient preparation. However, such 1D PCs are usually unstable as the reflectance will red shift at high temperature. Herein, we study the thermal stability of 1D PCs by post-thermal self-assembly. In general, the 1D PCs with lamellar structures are prepared by solvent annealing self-assembly of bottlebrush block copolymers with hard main chain, polystyrene-block-poly(tert-butyl acrylate) (H(PS-b-PtBA)). At temperatures higher than the glass transition temperature of side chains and main chain, the 1D PCs start to post self-assembly, which reaches equilibrium state when treated at high temperature for 8 h. Correspondingly, the reflectance of the 1D PCs red shifts from purple to blue gradually with temperature increase. Scanning electron microscope characterization shows that after thermal treatment, the domain spacing of the lamellar phases is increased from 108 nm to 160 nm, which results in the red shift of the reflectance wavelength. The red shift of the 1D PCs is related to the metastable self-assembly of bottlebrush block copolymers, which will further self-assemble at high temperatures to increase the domain spacing. After reaching equilibrium, the 1D PCs are thermal stable, which shows potential in high temperature resistance.

Heat triggered shape memory behavior of poly(tert-butyl acrylate) based star-block copolymers in physiological range

A series of poly(tert-butyl acrylate) (PtBA) based star-block copolymers were synthesized to obtain physically cross-linked shape memory polymers (SMPs) with body temperature triggering. First, PtBA star polymers were prepared via atom transfer radical polymerization (ATRP) to form the hard segment. Then star polymers were used as macro-initiators (MI) and combined with linear/non-linear derivatives of poly(ethylene glycol) (PEG), which build the soft segment. Characteristics of star-block copolymers were controlled by fraction, molecular weight and topology of the soft segment. Copolymers were prepared with varying soft segment ratio from 5.3 to 55.4 wt% and Tm of soft segment is adjusted between 28.9 and 55.6 °C. PtBA based copolymers with enhanced hydrophilicity (from 86.3 to 57.6°) exhibited Tm based shape memory behavior around body temperature with good shape recovery (Rr = 98.5%) and shape fixity (Rf = 98%).

Synthesis, properties and biodegradability of cross-linked amphiphilic Poly(vinyl acrylate)-Poly(tert-butyl acrylate)s by photo-initiated radical polymerization

The novel amphiphilic poly(vinyl acrylate)-poly(tert-butyl acrylate) based networks are produced by light-induced photo-initiated radical polymerization between poly(vinyl acrylate) (PVAcr), obtained by using hydroxyl moieties of poly(vinyl alcohol) (PVA), and tert-Butyl acrylate (tBA) monomer. PVA is modified by acryloyl chloride to obtained the corresponding acrylate functionalities (PVAcr). The achieved PVAcr is crosslinked with different amount of tBA (PVAcr:tBA = 0.005:1 and 0.005:2 by mole) to give desired structures (PVAcr-PtBA-1 and PVAcr-PtBA-2) in the presence of 2,2-Dimethoxy-2-phenylacetophenone (DMPA) at λ = 350 nm under nitrogen atmosphere. The structure, wettability, thermal and biodegradability properties of the pristine PVA and achieved networks are evaluated as a function of tBA loading by Fourier transform infrared (FT-IR) spectroscopy, water contact angle (WCA) measurement, thermogravimetric (TGA) and differential scanning calorimetry (DSC) analyses and biodegradation test, respectively. The results indicate that PVAcr-PtBA-2 obtained by higher tBA loading is less hydrophilic and biodegradable, but have improved thermal properties compared to pure PVA, and PVAcr-PVAcr control sample and PVAcr-PtBA-1.

A Macrocyclic Ruthenium Carbene for Size-Selective Alkene Metathesis.

The synthesis of amacrocyclic Ru carbene catalyst for selective cross alkene metathesis is reported. The new catalyst showed different reactivity for various type 1 alkenes in homodimerization which correlated with the aggregrate size of the allylic substituent. The altered reactivity profile allowed for selective product formation in competition cross alkene metathesis between two different type 1 alkenes and tert-butyl acrylate. Selectivity in these reactions is attributed to the ability of themacrocyclic catalyst to differentiate alkenes based on their size. Two preparative examples of cross metathesis with the macrocyclic catalyst are also provided.

Effect of poly(acrylic acid) architecture on setting and mechanical properties of glass ionomer cements

ObjectiveThis work focuses on the influence of poly(acrylic acid) (PAA) architecture (linear or branched) on setting behavior and compressive strength of glass ionomer cements (GICs). MethodsBranched and linear poly(acrylic acid)s were synthesized according to the Strathclyde methodology or by free radical polymerization. They were characterized by 1H-NMR spectroscopy and size exclusion chromatography to determine their molecular weight and size distribution. GIC setting was characterized by oscillating rheometry and time-dependent FTIR spectroscopy. In addition, compressive strength was tested on cylindrical samples (6 × 4 mm; n = 8/cement composition) after storage in deionized water at 37 °C for one day. ResultsWe used two different routes to prepare PAA. One direct route in order to provide straightforward access to branched PAA and a two-step approach in order to get more control about the PAA molecular weight using tert-butyl acrylate (tBA) for polymerization with subsequent deprotection. Using the second approach we obtained several linear PAA of which a mixture was used in order to mimic the molecular weight and size distribution of branched PAA. This allowed the direct comparison of properties relying only on the polymer architecture. Comparing linear PAA to branched samples in general led to faster setting but at the same time decreased the compressive strength. Increasing molecular weight of branched PAA resulted in even faster GIC setting while increasing compressive strength and this correlates well with the trends reported for linear PAA in literature. Mixing of branched and linear PAA, however, turned out to be an effective way of tailoring GIC properties. Significance: our results suggest that both molecular weight and dispersity need to be considered when choosing suitable PAA architecture for obtaining specific GIC properties.

Self-Adjuvanting Peptide Vaccines Against Cervical Cancer

Background Cervical cancer is a common cause of cancer-related deaths in women worldwide, with a fatality rate second only to breast cancer. Human papillomaviruses (HPVs) are the main causative agents of cervical cancer, and are therefore obvious targets for vaccine development. Although two prophylactic HPV vaccines have been commercialized, therapeutic vaccines against HPVs have not been developed yet. Current vaccine technologies emphasize the power of small particles in targeting immune cells, and particles of 20-50 nm have been reported to induce optimal immune responses against a variety of pathogens and cancers. Methods We synthesized new nanoparticle-based vaccines against cervical cancer by using antigenic 8Qmin peptide epitope derived from HPV-16 E7 protein, a hydrophilic poly-(L-glutamic acid) (PGA) linker, and an 8-arm poly (tert-butyl acrylate) dendrimer-based delivery system (D8). Results Four different peptides containing 8Qmin and PGA of different lengths were successfully synthesized with high yield and purity. These were then conjugated to alkyne-functionalized D8 by copper-catalyzed alkyne-azide cycloaddition “click” reaction. The conjugates self-assembled into nanoparticles, with decreased particle size corresponding to a greater number of Glu units. The four vaccine candidates were tested in C57 black 6 (C57BL/6) mice bearing well-established (7-day-old) tumors to examine their therapeutic effects. Conclusion Interestingly, only one conjugate delayed tumor growth, and montanide adjuvanted antigen, used as a positive control, failed to demonstrate any therapeutic effect.

Enhanced pretreatment of tert-butyl acrylate production wastewater by fluidized/fixed bed treatment system

Purifying wastewater and saving energy have become important prerequisites for global sustainable development. Currently, the application of various wastewater treatment processes for tert-butyl acrylate production wastewater is still restricted by energy-intensive factors. Aiming at addressing the trade-offs in water-energy nexus in purification of tert-butyl acrylate production wastewater, this study proposed a fluidized/fixed bed treatment system for catalytic oxidation purification of tert-butyl acrylate production wastewater. A high calorific value of rectification residue produced by the production of tert-butyl acrylate was introduced to simultaneously achieve low energy consumption and efficient purification of tert-butyl acrylate production wastewater and rectification residue. The effects of the operating conditions of fluidized and fixed beds and their coupling process on the purification effect of tert-butyl acrylate production wastewater were evaluated. Results showed that the efficiency of purifying tert-butyl acrylate production wastewater and rectification residue using the fluidized/fixed bed treatment system was considerable. The calculation results showed that the thermal balance of the system was enhanced due to the introduction of rectification residue, and the energy-saving rate reached 18%. Tert-butyl acrylate production wastewater was oxidized to small-molecule chemicals by proton transfer and demethylation during degradation process which was investigated by gas chromatography–mass spectrometry. Stability experiments indicated that the average removal efficiency of chemical oxygen demand in fluidized/fixed bed treatment system was 97.0%–98.5% for 600 h of continuous operation. The Cu/Ce/Mn catalyst exhibited good stability. Therefore, fluidized/fixed bed treatment system can effectively purify high-concentration organic wastewater and is a promising technology.

Phase behavior of poly(ε-caprolactone)-b-poly(tert-butyl acrylate) block copolymer at the air/water interface

Thermodynamic phase behavior of poly(ε-caprolactone)-b-poly(tert-butyl acrylate) (PCL-b-PtBA) block copolymers at the Air/Water (A/W) interface was studied by analyzing surface pressure-area isotherms. Optical microscopy and atomic force microscopy were utilized to reveal the morphological features of three-dimensional domains grown in the Langmuir films. A series of PCL-b-PtBA block copolymers synthesized for this study share the same PCL block with molecular weight of Mn = 7.5 kg•mol−1, while the length of PtBA blocks varies. Homogeneous Langmuir monolayers were formed at the A/W interface before reaching the dynamic collapse pressure of PCL blocks. The growth of PCL flat-on crystalline domains predominately took place during the plateau regime after the collapse transition, though nucleation process occurred prior to the collapse transition. The tethered PtBA blocks remain as a monolayer at the A/W interface prior to the second collapse pressure at ∼ 24 mN•m−1, which is comparable to the collapse pressure of PtBA homopolymer monolayer. Depending on the length of PtBA blocks, the block copolymer crystals exhibit morphological features from distorted hexagonal shape, truncated parallelogram, dendrites with defects, stripes, and nano-scale domains, suggesting that the tethered amorphous PtBA block significantly reduced the mobility and packing efficiency of PCL blocks during the crystallization of PCL-b-PtBA copolymers at the A/W interface.

Investigation on the atom transfer nitroxide radical polymerization (ATNRP) mechanism and its versatile applications for bimodal polymers

The atom transfer nitroxide radical polymerization (ATNRP) was developed based on the synergistically happened nitroxide radical coupling (NRC) reaction, atom transfer radical polymerization (ATRP) and nitroxide mediated radical polymerization (NMRP) procedures. The ATNRP of styrene (St) and tert-butyl acrylate (tBA) monomers were systematically studied at different temperature with various molar ratio of [HO-TEMPO]0/[EBiB]0. In the case of St, both ATRP and NMRP can be combined into an ATNRP technique, while the polymerization rate was lowered with the increase of [HO-TEMPO]0/[EBiB]0. With the increase of temperature, the polymerization showed an increased polymerization rate. Alternatively, in the case of tBA, with the addition of HO-TMEPO agent, partial PtBA was terminated by the side reactions of H-abstraction or disproportionation. The remained PtBA was still functionalized with bromide group, and the ATRP can be still continued for a bimodal PtBA. Finally, the resulted PS or PtBA can be further cross-chain-extended by tBA or St, and the bimodal diblock copolymers can be generated. The compositions of the obtained bimodal homopolymer or diblock copolymer can be well controlled by the amount of [HO-TEMPO]0/[EBiB]0.

Ag nanoparticles encapsulated in carboxyl-functionalized hollow microporous organic nanospheres for highly efficient catalysis applications

In this work, we present a novel synthesis of Ag nanoparticles encapsulated in carboxyl-functionalized hollow microporous organic nanospheres (Ag@COOH-HMONs) by a combination of hyper-cross-linking mediated self-assembly and simply impregnation method, in which the COOH-HMONs supports were prepared via a Friedel-Crafts alkylation reaction by using polylactide-b-poly(tertbutyl acrylate)-b-polystyrene (PLA-b-PtBA-b-PS) triblock copolymer as precursors. Owing to the abundant carboxyl groups in the cavity of COOH-HMONs, highly dispersed silver nanoparticles can be successfully anchored into COOH-HMONs to produce Ag@COOH-HMONs via an ion exchange with AgNO3 following by an in-situ reduction of sodium borohydride (NaBH4). The obtained Ag@COOH-HMONs exhibit the high catalytic activities for the reduction of MB and nitroaromatic compounds as well as selective oxidation of thiol and styrene due to their high surface area, hierarchical porosity and yolk-shell nanostructure. This approach of constructing novel metal@porous organic polymers is expected to open doors for new types of yolk-shell structural catalysts for practical applications.

Controlled synthesis and self-assembly of amphiphilic copolymers based on 2,2,3,3,4,4,5,5-octafluoropentyl acrylate and acrylic acid

The reversible addition–fragmentation chain transfer (RAFT) polymerization of 2,2,3,3,4,4,5,5-octafluoropentyl acrylate (OFPA) in the presence of different concentrations of S,S-dibenzyl carbonotrithioate as chain transfer agent (CTA) was investigated. The estimate of Ctr was defined using the size-exclusion chromatography measurements. Copolymers of acrylic acid and OFPA with different microstructure were synthesized by three methods: block copolymerization, copolymerization of acrylic acid and OFPA, and chemical modification of copolymer of tert-butyl acrylate and OFPA. Copolymerization of abovementioned monomer pairs was studied. The reactivity ratios were calculated by using the Fineman–Ross and Kelen–Tudos models, as well as the method of least squares. Aggregation behavior of the obtained amphiphilic copolymers at the air/water interface was defined by the Langmuir monolayer technique. Monomolecular films of amphiphilic copolymers were studied using atomic force microscopy. The effect of the chain microstructure, the acrylic acid content in the copolymer, and subphase pH on the isotherm curves were shown.

Scalable synthesis of fluorescent organic nanodots by block copolymer templating

Scalable synthesis of fluorescent organic nanodots by block copolymer templating

Hydrophobic Poly(tert-butyl acrylate) Photonic Crystals towards Robust Energy-Saving Performance.

Photonic crystals (PCs) have been widely applied in optical, energy, and biological fields owing to their periodic crystal structure. However, the major challenges are easy cracking and poor structural color, seriously hindering their practical applications. Now, hydrophobic poly(tert-butyl acrylate) (P(t-BA)) PCs have been developed with relatively lower glass transition temperature (Tg ), large crack-free area, excellent hydrophobic properties, and brilliant structure color. This method based on hydrophobic groups (tertiary butyl groups) provides a reference for designing new kinds of PCs via the monomers with relatively lower Tg . Moreover, the P(t-BA) PCs film were applied as the photoluminescence (PL) enhanced film to enhance the PL intensity of CdSe@ZnS QDs by 10-fold in a liquid-crystal display (LCD) device. The new-type hydrophobic force assembled PCs may open an innovative avenue toward new-generation energy-saving devices.

Effect of Chain Microstructure and Subphase pH on the Surface Properties and Aggregation Behavior of Amphiphilic Copolymers Based on Fluoroacrylates

Copolymerization of 2,2,3,3,4,4,5,5-octafluoropentyl acrylate (OFPA) and acrylic acid (AA), OFPA and tert-butyl acrylate (t-BA) in presence ofdibenzylcarbonotrithioate (BTC) and polymeric RAFT-agents was studied, reactivity ratios were calculated. It was shown that type of RAFT-agent can influence on chain microstructure of obtained polymers. Aggregation behavior of obtained amphiphilic copolymers with different microstructures at the air/water interface was characterized by the Langmuir monolayer technique. The effect of the microstructureand subphase pH on the isotherm curves were shown.

PH-responsive AIE-active Polyethylene-based Block Copolymers

A novel synthetic strategy towards pH-responsive aggregation-induced emission (AIE)-active tetraphenylethene (TPE)-functionalized polyethylene-based block copolymers is presented. Tris(3-(4-(1,2,2-triphenylvinyl)phenoxy)propyl)borane was used to initiate the polyhomologation of dimethylsulfoxonium methylide to afford well-defined α-TPE-ω-OH linear polyethylenes (PE). The terminal hydroxyl groups were transformed to atom transfer radical polymerization (ATRP) initiating sites by esterification with α-bromoisobutyryl bromide, followed by polymerization of tert-butyl acrylate (tBA) to provide TPE-PE-b-PtBA block copolymers. After hydrolysis of the tBu group to COOH group, the corresponding pH-responsive TPE-PE-b-PAA block copolymers were obtained. All synthesized block copolymers revealed AIE behavior either in solution or bulk. Due to the pH-responsivity of PAA chains, the aggregation state at different pH and consequently the fluorescence intensity changed. Also, the synthesized block copolymers exhibited ion-specificity fluorescence properties.

A polymer-supported salen-palladium complex as a heterogeneous catalyst for the Mizoroki-Heck cross-coupling reaction

In this work, the catalytic performance of a polymer-supported Pd(II)-salen complex (PS-Pd-salen) as an effective and environmentally friendly catalyst for the Mizoroki-Heck CC cross-coupling reaction is presented. The PS-Pd-salen complex was employed as a catalyst for Mizoroki-Heck reactions of an aryl halide with various terminal alkenes (Styrene, Methyl acrylate, Ethyl acrylate, n-butyl acrylate, tert-Butyl acrylate) under phosphine free conditions. Moreover, a range of Mizoroki-Heck reactions using different polar solvents, co-solvents, and bases has been investigated. Aryl iodides and bromides with terminal alkene are well activated in CC coupling reactions. All products were isolated by column chromatography as liquids/white to off-white crystalline solids and confirmed by 1H and 13C NMR spectroscopy. The catalyst could be easily separated by filtrations and reusability of catalyst was also assessed under optimized conditions. The hot filtration test revealed that the catalyst was truly heterogeneous, very active and stable under the reaction conditions and could be reused up to fifth cycles with analogous activities to that of the fresh catalyst. High catalytic activity at a low concentration (30 mg) and flexibility under mild reaction conditions, simple product work-up towards Mizoroki-Heck reactions indicated that PS-Pd-salen was an efficient catalyst for CC coupling reactions.

Hierarchically spacing DNA probes on bio-based nanocrystal for spatial detection requirements

Sterically spacing and locating functional matters at the nanoscale exert critical effects on their application, especially for the fluorescence probes whose aggregation causes emission quenching. Here we achieved a hierarchical spacing strategy of DNA fluorescence probes for ion detection via locating them separately on rod-like cellulose nanocrystals (CNCs) and further isolating CNCs by pre-grafting long molecular chains. Controlling chemical structure of CNC and location degree could adjust the inter-space of DNA probes (with a molecular length of ca. 3.6 nm) in a range of 3.5–6.5 nm with a gradient about 0.2 nm. A length up to micrometer scale of the CNC nanorods was necessary to provide DNA probes with well-separated grafting locations and enough freedom, which brought a vast linear detection range from 10 nmol/L to 5 μmol/L of Hg2+ concentration. The abundant reactive sites on CNC allowed a grafting pre-location of poly (tert-butyl acrylate) (PtBA) to promote the isolation of DNA probes. Controlled radical polymerization was employed to adjust the length of PtBA molecular chains, which increased the linear sensitivity coefficient of Hg2+ detection by ca. 2.5 times. This hierarchical nanoscale spacing concept based on chemical design can hopefully conduce to the development of biosensor and medical diagnosis. A hierarchical spacing strategy was applied to separate DNA fluorescent probes on CNCs and detect ion concentration linearly. The first-level spacing was to locate probes uniformly on CNCs, obtaining a wide linear range; and the second-level spacing was to isolate CNCs with polymer, obtaining an increased linear coefficient.