Bulk Copolymerization Research Articles

Electro-responsive Molecularly Imprinted Polymers (E-MIPs) for Rapid Detection of Progesterone in Human Serum Samples.

Rapid and reagent-free detection of progesterone (P4) is crucial in point-of-care (POC) measurement due to its important role in the human endocrine and central nervous system. Currently available technologies for P4 detection are often not rapid or require reagents, limiting their use in POC settings. In this work, a self-signaling electrochemical sensing platform for rapid detection of P4 is developed by using electroactive molecularly imprinted polymers (E-MIPs). E-MIPs possess the ability to transduce the molecular recognition event into a measurable electrochemical signal. The E-MIPs are prepared by bulk copolymerization of acrylic acid (AA) and ferrocenylmethyl methacrylate (FcMA) in the presence of P4 followed by its removal from the polymer matrix. By incorporation of ferrocene moieties, the MIP gains intrinsic electroactivity, enabling label-free and direct electrochemical detection of P4 levels. Electrochemical techniques, including cyclic voltammetry and electrochemical impedance spectroscopy, were employed to elucidate the electron transport reaction responsible for the MIP's intrinsic electroactivity. Additionally, the predetermined complementary binding sites confined to the small working area of the screen-printed carbon electrode (SPCE) within the E-MIP matrix facilitate rapid P4 binding, achieving completion within 120 s. The developed E-MIP sensing platform was used for the rapid detection of P4 levels in human serum samples. The short incubation times reported for the E-MIP sensing platform would be beneficial in minimizing the nonspecific binding in the real-world samples. We believe that the proposed E-MIP sensing platform can be applied to clinical samples for detecting fluctuations in P4 levels.

Synthesis, characterization and properties of vinyl-terminated poly[dimethylsiloxane-co-methyl(phenyl)siloxane]

Phenyl-containing polysiloxanes have better thermal stability, low-temperature flexibility, and room-temperature damping performance than polydimethylsiloxanes. Poly [dimethylsiloxane-co-methyl (phenyl)siloxane] and poly (dimethylsiloxane-co-diphenylsiloxane) were synthesized through a bulk copolymerization of octamethylcyclotetrasiloxane and methylphenylcyclosiloxane mixture or octaphenylcyclotetrasiloxane, and the structure and properties of the copolysiloxanes were comparatively studied. The phenyl content in poly [dimethylsiloxane-co-methyl (phenyl)siloxane] can be as high as 50 mol%. With the increment of the phenyl content, the thermal stability of the copolysiloxanes is dramatically improved as evaluated by thermal gravimetric analysis. At a given phenyl content, poly [dimethylsiloxane-co-methyl (phenyl)siloxane] has higher thermal stability than poly (dimethylsiloxane-co-diphenylsiloxane). The former is more difficult to crystalline at low temperatures and has lower room temperature viscosity than the latter as confirmed by differential scanning calorimetry and rotational rheometer. The copolysiloxanes is mixed with hydrogen-containing polysiloxane and silica, and vulcanized at elevated temperature to get copolysiloxane composites with good damping properties, oil resistance, and low-temperature resistance. This study not only enriches the fundamental academic research on functional polysiloxanes, but also provides useful technical references for practical applications of phenyl silicone rubber.

Nitroxide mediated controlled radical polymerization of α‐Methylene‐γ‐Butyrolactone

AbstractThe controlled polymerization of α‐methylene‐γ‐butyrolactone (MBL, a naturally occurring sesquiterpene lactone found in tulips) was performed by nitroxide mediated polymerization (NMP) using the alkoxyamine Dispolreg 007 as the initiating system at 80 °C in 50 wt% DMSO. Features of a reversible‐deactivation radical polymerization (RDRP) were observed with a linear growth of the macro‐radical with conversion and a relatively low dispersity (Ð ≤ 1.45). The P(MBL) homopolymer chain ends were mostly re‐activatable as the chain extensions with styrene (S) and glycidyl methacrylate (GMA) in DMSO were successful. Interestingly, the polymerization of MBL initiated by 2‐methyl‐2‐[N‐tert‐butyl‐N‐(1‐diethoxyphosphoryl‐2,2‐dimethylpropyl)‐aminoxy]‐N‐propionyloxysuccinimide (known as NHS‐BlocBuilder) under various experimental conditions did not produce well‐defined P(MBL), possibly due to an excessively high equilibrium constant. However, the bulk copolymerization of MBL with 10–21 mol% of β‐myrcene (Myr, another renewable monomer from the terpene family) initiated by NHS‐BlocBuilder at 100–110 °C led to all the features of a controlled system. The SG1 chain end fidelity of the resulting P(MBL‐co‐Myr) copolymer was confirmed via 31P NMR and by re‐initiating successfully the copolymer chains with a mixture of GMA and Myr monomers at 120 °C in DMSO.

Preparation of a Structural Polyimide Foam Plastic Based on a Bulk Copolymer of Acrylonitrile and Methacrylic Acid

Foaming of particles of acrylonitrile–methacrylic acid copolymer in the temperature interval 160–220°С was studied. As shown by IR spectroscopy, the final polymer matrix of the foam plastics consists of glutarimide fragments. Thermogravimetric analysis shows that the products start to degrade at a high temperature (about 350°С). The effect of the prolonged heat treatment at 150–190°С on the physicomechanical characteristics of the foamed plastics was examined.

Hybridizing a Dual-Cross Network and a Linear Glassy Polymer for Dynamic Contributions to High Mechanical Toughness Based on Phase-Separated Structures

Bulk copolymerization of alkyl acrylate and cyclodextrin (CD) host monomers forms a single movable cross network (SC), in which the CD units act as movable cross-linkers. Moreover, the bulk copolymerization of the CD monomer and main chain monomer in the presence of SC results in dual-cross-network (DC) elastomers. DC elastomers result in good toughness (Gf). Here, to improve Gf and Young’s modulus (E), we hybridized DC elastomers with tertiary glassy polymers, which are called DCP elastomers. We prepared the DCP elastomers by photopolymerization of N,N-dimethylacrylamide (DMAA) and poly(2-methoxyethyl acrylate) (MEA) in the presence of DC. A DCP elastomer with a suitable weight percent (wt %) of the glassy polymer shows high Gf (108.4 MJ m–3) and E (223.4 MPa) values. Dynamic mechanical analysis (DMA) and in situ small-angle X-ray scattering (SAXS) measurements under uniaxial stretching indicate multiple deformations based on phase-separated structures. We suggest that the phase-separated structures of DCP elastomers cause a large stress dissipation, which contributes to high toughness.

Benzoxazine-sulfur-Chitosan based freestanding beads: Synthesis, characterization, stability, and removal of mercury and oil

Environmentally benign dual-functional sorbents are desired for easy removal of various and variably located pollutants such as heavy toxic metal ions and crude oil from water. Herein, we have developed sorbents based on sustainable feedstocks using a facile methodology. Bulk copolymerization of biobased benzoxazine (C-fa, cardanol ‘C’ and furfurylamine ‘fa’) with elemental sulfur (S, industrial waste) proceeded in a single step (10 min) to form poly(benzoxazine-ran-sulfur). Bare chitosan (CS) beads and CS/poly(benzoxazine-ran-sulfur) composite beads are fabricated, and performance is analyzed. CS/poly(benzoxazine-ran-sulfur) beads reveal good mechanical and hydrolytic stability, and effectively remove crude oil (8-times the sorbent weight) with appreciable recyclability. These composite beads also demonstrated well-defined mercury ion uptake kinetics, along with a very high mercury ion capture capacity of 334.5 mg of mercury per gram of polymer as calculated from the Langmuir isotherm model and followed a pseudo-second-order kinetics. Designed waste-derived sorbents hold a great promise in tackling the diverse nature of pollutants essential for water purification.

Radical-Mediated Ring-Opening Photopolymerization for Semicrystalline Thermoplastic Additive Manufacturing

Conventional approaches to stereolithographic additive manufacturing (SLA) employ liquid resin formulations based on multifunctional (meth)acrylates and epoxides that afford cross-linked polymeric networks upon polymerization. Nevertheless, the utilization of resins that yield semicrystalline thermoplastics provides facile access to physical and mechanical properties that are otherwise difficult to attain, such as high toughness and resistance to solvent swelling as well as additional postfabrication processing options that can be used to extend the life cycle of three-dimensional printed polymers. Here, we report the SLA-based additive manufacturing of semicrystalline thermoplastics utilizing the radical-mediated ring-opening photopolymerization of seven- and eight-membered cyclic allylic sulfides. Photopolymerization of resin formulations incorporating seven- and eight-membered cyclic allylic sulfides and crystallization of the resultant (co)polymers were examined using Fourier transform infrared spectroscopy, photorheology, and isothermal photo-differential scanning calorimetry. The formulated resins were found to polymerize and subsequently crystallize rapidly upon irradiation under ambient conditions. The mechanical properties of stereolithographically printed copolymers approached the bulk copolymer mechanical properties, demonstrating unusually strong interlayer adhesion atypical of layerwise, stereolithographic printing of semicrystalline polymers. Finally, high-quality, recyclable, semicrystalline thermoplastic parts were printed and melted down, demonstrating the potential for these semicrystalline materials to provide a path for improved sustainability of polymeric parts produced via SLA.

Thermo- and pH-Sensitive Behavior of Copolymers of N-Vinylcaprolactam with N-Vinylimidazole

Free-radical copolymerization in bulk has afforded copolymers of N-vinylcaprolactam and N‑vinylimidazole (40–60 mol %). Thermosensitive behavior of aqueous solutions of the copolymers has been probed over wide pH range by means of dynamic and static light scattering as well as high-sensitivity differential scanning calorimetry. Three regions of thermally induced conformational behavior have been observed with the change in the medium pH from the alkaline to acidic: phase separation region (I), region of the conformational transition into the mesoglobules state (II), and region of stable molecular solution of the poly-electrolyte (III). Significant polyelectrolyte effects have been revealed for the salt-free solutions of the copolymers, reflected in the presence of fast and slow diffusion modes in the relaxation time distributions. Moderate increase in the ionic strength with the addition of the low-molecular salt has led to shielding of the polyelectrolyte effects, yet the pH-dependent regions of the conformational behavior have not been affected much. The existence of different types of the thermally induced conformational behavior depending on pH has been explained by the balance between hydrophobic interactions involving the N-vinylcaprolactam units and electrostatic interactions of the weakly basic N-vinylimidazole units.

Phase separation kinetics of block copolymer melts confined under moving parallel walls: A DPD study

We use dissipative particle dynamics (DPD) simulations to study the effect of shear on domain morphology and kinetics of microphase separating critical diblock copolymer (BCP) bulk melts. The melt is confined within two parallel amorphous solid walls at the top and bottom of the simulation box. The shear is induced by allowing the walls to move in a direction with a specific velocity. We explore the following cases: (i) walls are fixed, (ii) only the top wall moves, (iii) both walls move in the same direction, and (iv) both walls move in opposite directions. After the temperature quench from an uniformly mixed state, we monitor the effect of shear on evolution morphology, scaling behavior, characteristic length scale and growth laws of the evolving system. The characteristic length scale follows typical power-law behavior at early times and saturates at late times when both walls are fixed. The length scale changes significantly with shear rates caused by wall velocities. The usual lamellar morphology, which is not achieved for case 1 within the considered simulation time steps, is noticed much earlier for the nonzero wall velocity cases. Specifically, it is seen much before in case 4 than in the other cases. We find that the shear viscosity decreases (shear-thinning) with shear rate for all the cases at a given coarsening time. Overall, we report the influence rule of shear rates on microphase separation kinetics of BCP melts. This study can provide a scheme to anticipate and design anisotropic microstructures under the application of externally controlled wall shear that may further guide in producing the various composite materials with superior mechanical and physical properties.

Preparation of a Structural Polyimide Foam Plastic Based on a Bulk Copolymer of Acrylonitrile and Methacrylic Acid

Preparation of a Structural Polyimide Foam Plastic Based on a Bulk Copolymer of Acrylonitrile and Methacrylic Acid

Synthesis of Copolymer from 1,3,5-Trioxane and -Caprolactone Catalysed by Treated Bentonite as Eco-Catalyst

This study presents a novel green method for copolymerizing 1,3,5-trioxane (TOX) with ε caprolactone (CL). This technique uses Maghnite-H+ (Mag-H+) as a bulk green catalyst. Various techniques were used to confirm the structure of the resulting copolymer. The influencing factors on the copolymerization reaction were also studied. The results show that the best copolymer yield (46.3 %) was obtained via bulk copolymerization at a temperature of 353 K for a reaction time of 8 h.

Emergence and Stability of Hierarchical Structures under Cylindrical Confinement

AbstractFocusing on the formation of hierarchical structure under cylindrical confinement, the self‐assembly of A(BC)2B multiblock copolymer of chain length N in a nanopore with size R is studied using the self‐consistent field theory. The hierarchical concentric ring (HCk), hierarchical perforated cylinder (HPk), hierarchical helix (HHk), and even hierarchical disk (HDk) is obtained with different number of mid‐thin layers k via a proposed design principle. The results show that large pore size and χAB favor the hierarchical structure with more k, while χBC prefers hierarchical structure with less k, consistent with the results of hierarchical structure in bulk. By investigating the effect of the volume fraction of the tail A block (fA), the phase transition sequence, HCk → HPk → HHk → HDk is explored, which shares the same transition of multiblock copolymer in bulk with Lk → Gk → Ck → Sk. Finally, the phase diagram with respect to the fA and R is explored, where the stability regime of these hierarchical structures is well understood. The results provide a compelling panacea for the fabrication of hierarchical 3D nanostructures under confinement.

Effect of Disparity in Self Dispersion Interactions on Phase Behaviors of Molten A-b-B Diblock Copolymers.

Phase behaviors of molten A-b-B diblock copolymers with disparity in self dispersion interactions are revisited here. A free energy functional is obtained for the corresponding Gaussian copolymers under the influence of effective interactions originating in the localized excess equation of state. The Landau free energy expansion is then formulated as a series in powers of A and B density fluctuations up to 4th order. An alternative and equivalent Landau energy is also provided through the transformation of the order parameters to the fluctuations in block density difference and free volume fraction. The effective Flory χ is elicited from its quadratic term as the sum of the conventional enthalpic χH and the entropic χS that is related to energetic asymmetry mediated by copolymer bulk modulus. It is shown that the cubic term is balanced with Gaussian cubic vertex coefficients in corporation with energetics to yield a critical point at a composition rich in a component with stronger self interactions. The full phase diagrams with classical mesophases are given for the copolymers exhibiting ordering upon cooling and also for others revealing ordering reversely upon heating. These contrasting temperature responses, along with the skewness of phase boundaries, are discussed in relation to χH and χS. The pressure dependence of their ordering transitions is either barotropic or baroplastic; or anomalously exhibits anomalously both at different stages. These actions are all explained by the opposite responses of χH and χS to pressure.

Digital Strategies to Improve Product Quality and Production Efficiency of Fluorinated Polymers: 1. Development of Kinetic Model and Experimental Verification for Fluorinated Ethylene Propylene Copolymerization

Digitalization of industrial polymerization processes represents an effective and efficient approach for product-grade upgrading and for production efficiency improvement. A mechanistic model based on the first principles of elementary reactions and mass balances provides a powerful tool in the practice of process digitalization. In this work, we developed a comprehensive kinetic model for the batch process of bulk copolymerization of tetrafluoroethylene with hexafluoropropylene. A series of experimental runs were carried out under various conditions. The fluorinated ethylene propylene copolymer samples were collected, with the monomer conversions, copolymer compositions, and polymer molecular weights, as well as the melting and crystallization properties, fully analyzed. The model was then correlated with the data for estimation of the model parameters. The reactivity ratios were found to be r1 = 65.5 and r2 = 2.6 × 10–3. With a whole set of estimated parameters, the model was used to simulate results under different polymerization conditions close to industrial production processes, which were further verified with additional experimental data. The agreement between simulated and experimental results was good. The experimentally verified model provides a powerful tool for industrial process optimization aiming at improvement of product quality and production efficiency.

Facile synthesis of azobenzene-containing polyamide 6 with low melting point and good anti-dripping performance

An inherent functional PA6 copolymer (PADA) with low melting point and good anti-dripping performance was designed via a facile bulk copolymerization method. Azobenzene (self-crosslinked unit) as the functional segment was introduced into the PA6 backbone under the favorable assistance of ethylene glycol (EG, a chain-linker). Specifically, a satisfactory reduction of approximately 50 °C in melting point was achieved for PADAs compared with PA6 due to the destroyed regularity of the molecular chain. Meanwhile, the PADAs reached an LOI value of 28.2% with totally suppressed melt-dripping behavior, and the formed crosslinked network that originated from the synergistic effect of azobenzene and EG during combustion was proved to be an essential factor for the improved anti-dripping performance. The proposed synthesis method overcomes the difficulty of the requirement for the absolutely equivalent molar ratio of amine to carboxyl groups in PA6 copolymerization, and thus appeals to a broader focus on developing traditional PA6.

Preparation of dual-cross network polymers by the knitting method and evaluation of their mechanical properties

Bulk copolymerization of alkyl acrylates and cyclodextrin (CD) host monomers produced a single movable cross-network (SC). The CD units acted as movable crosslinking points in the obtained SC elastomer. Introducing movable crosslinks into a poly(ethyl acrylate/butyl acrylate) copolymer resulted in good toughness (Gf) and stress dispersion. Here, to improve the Young’s modulus (E) and Gf of movable cross-network elastomers, the bulk copolymerization of liquid alkyl acrylate monomer swelling in SC gave another type of movable cross-network elastomer with penetrating polymers (SCPs). Moreover, the bulk copolymerization of alkyl acrylate and the CD monomer in the presence of SC resulted in dual cross-network (DC) elastomers. The Gf of the DC elastomer with a suitable weight % (wt%) of the secondary movable cross-network polymer was higher than those of the SCP or SC elastomers. The combination of suitable hydrophobicity and glass transition of the secondary network was important for improving Gf. Small-angle X-ray scattering (SAXS) indicated that the DC elastomers exhibited heterogeneity at the nanoscale. The DC elastomers showed a significantly broader relaxation time distribution than the SC and SCP elastomers. Thus, the nanoscale heterogeneity and broader relaxation time distribution were important to increase Gf. This method to fabricate SCP and DC elastomers with penetrating polymers would be applicable to improve the Gf of conventional polymeric materials.

Influence of thermal runaway in styrene–acrylonitrile bulk copolymerization revealed by computational fluid dynamics modeling

AbstractThe computational fluid dynamics (CFD) and kinetic‐based moment methods coupled approach is adopted to simulate the bulk copolymerization of styrene–acrylonitrile (SAN) in a stirred tank reactor. Numerical simulations are carried out to investigate the impacts of impeller speed, monomer ratio, initiator ratio, and initial reaction temperature on the copolymerization process and product properties. Particularly, the Chaos theory is selected as a criterion for evaluating the occurrence of the thermal runaway. The Flory's and Stockmayer's distributions are employed to calculate chain length distribution and copolymer composition distribution of copolymer. The simulation results highlight that the appearance of thermal runaway can be postponed by properly increasing the rotation speed, decreasing the initiator loadings, initial acrylonitrile contents and initial reactor temperature. Furthermore, significant differences exist in the product properties that predicted by the ideal and non‐ideal models, which demonstrates that the temperature heterogeneity plays a crucial role in SAN copolymerization. This study could offer references for the safe operation and design of polymerization processes.

Epoxy resins and composites from epoxidized linseed oil copolymers with cyclohexene oxide

New materials were made by copolymerization of epoxidized linseed oil (ELO) and cyclohexene oxide (CHO) catalyzed by tris(pentafluorophenyl)borane (BCF). Pure polymerized ELO and polymerized CHO were prepared to study reactivity and properties of starting components in the presence of the selected catalyst. The catalyst furnished high conversion of CHO at a very high rate. Properties of epoxy resins are improved by increasing the amount of CHO. The copolymerization in bulk is fast at room temperature with increasing CHO content, turning violent even at low catalyst loadings, hence, the amount of CHO is limited to about 10% to allow for manageable pot life and heat management. Post-curing is required for improving mechanical properties. The materials are hard, transparent, clear glasses, with glass transitions around 45 °C. Tensile strengths of 27 MPa and flexural moduli over 1 GPa were observed. The feasibility of using these highly hydrophobic triglyceride-based epoxy resins in glass-reinforced composites and foams was demonstrated successfully. Potential applications for these novel systems are in optical materials, potting, encapsulating, and casting resins, foams and as matrix resins in composites. The preparation involves a simple mixing process and an inexpensive epoxidized vegetable oil.

ТЕРМИЧЕСКОЕ ПОВЕДЕНИЕ СОПОЛИМЕРОВ МАЛЕИМИДА С АЛКИЛМЕТАКРИЛАТАМИ

Copolymers of maleimide with methyl- and allyl methacrylate have been prepared by the method of radical copolymerization in bulk. It was established that, regardless of the composition of the initial monomer mixture, copolymerization proceeded with the formation of random copolymers enriched with acrylate monomer units. Maleimide copolymers have high thermal stability up to 320 °C.

Antimicrobial and anticancer activities of copolymers of tri-O-acetyl-D-glucal and itaconic anhydride

This paper reports the synthesis and characterization of monomers itaconic anhydride (IA) and tri-O-acetyl-D-glucal (TAG) as well as 4,6-di-O- -acetyl-D-glucal (PSG). The homopolymers and copolymers of IA and TAG were synthesized via free radical copolymerization in bulk, using azobisisobutyronitrile as an initiator with different feed ratios of monomers. Their structural, molecular and thermal characterization was done using 1H-NMR spectroscopy, gel permeation chromatography and differential scanning calorimetry, respectively. The glass transition temperature (Tg) of copolymers was found in the range of 139?145 ?C. The highest Tg was found for IA?TAG2 copolymers, whereas IA?TAG4 copolymer showed lowest Tg. The molecular weight of the copolymers was in the range 5157?5499 g mol-1. The monomer TAG undergoes Ferrier rearrangement in water to give PSG. The antimicrobial activity of IA, TAG, PSG and IA?TAG copolymers was studied using the minimum microbicidal concentration-broth dilution method. TAG, IA and PSG, as well as homopolymer and copolymers of IA and TAG are excellent antimicrobial agents.