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Advanced Science (Weinheim,... Dec 2022Soft colloidal macromolecular structures with programmable chemical functionalities, size, and shape are important building blocks for the fabrication of catalyst...
Soft colloidal macromolecular structures with programmable chemical functionalities, size, and shape are important building blocks for the fabrication of catalyst systems and adaptive biomaterials for tissue engineering. However, the development of the easy upscalable and template-free synthesis methods to obtain such colloids lack in understanding of molecular interactions that occur in the formation mechanisms of polymer colloids. Herein, a computer simulation-driven experimental synthesis approach based on the supramolecular self-assembly followed by polymerization of tailored pyrazole-modified monomers is developed. Simulations for a series of pyrazole-modified monomers with different numbers of pyrazole groups, different length and polarity of spacers between pyrazole groups and the polymerizable group are first performed. Based on simulations, monomers able to undergo π-π stacking and guide the formation of supramolecular bonds between polymer segments are synthesized and these are used in precipitation polymerization to synthesize anisotropic microgels. This study demonstrates that microgel morphologies can be tuned from spherical, raspberry-like to dumbbell-like by the increase of the pyrazole-modified monomer loading, which is concentrated at periphery of growing microgels. Combining experimental and simulation results, this work provides a quantitative and predictive approach for guiding microgel design that can be further extended to a diversity of colloidal systems and soft materials with superior properties.
Topics: Microgels; Polymerization; Computer Simulation; Polymers; Colloids
PubMed: 36310110
DOI: 10.1002/advs.202204853 -
Dental Materials : Official Publication... Jul 2020Water sorption, high volumetric shrinkage, polymerization stress, and potential estrogenic effects triggered by leached compounds are some of the major concerns related...
OBJECTIVE
Water sorption, high volumetric shrinkage, polymerization stress, and potential estrogenic effects triggered by leached compounds are some of the major concerns related to BisGMA-TEGDMA co-monomer systems used in dental composites. These deficiencies call for the development of alternative organic matrices in order to maximize the clinical lifespan of resin composite dental restorations. This study proposes BisGMA-free systems based on the combination of UDMA and a newly synthesized diurethane dimethacrylate, and evaluates key mechanical and physical properties of the resulting materials.
METHODS
2EMATE-BDI (2-hydroxy-1-ethyl methacrylate) was synthesized by the reaction between 2-hydroxy-1-ethyl methacrylate with a difunctional isocyanate (1.3-bis (1- isocyanato-1-methylethylbenzene) - BDI). The compound was copolymerized with UDMA (urethane dimethacrylate) at 40 and 60wt%. UDMA copolymerizations with 40 and 60wt% TEGDMA (triethylene glycol dimethacrylate) were tested as controls, as well as a formulation based in BisGMA (bisphenol A-glycidyl methacrylate)-TEGDMA 60:40% (BT). The organic matrices were made polymerizable by the addition of DMPA (2.2-dimethoxyphenoxy acetophenone) and DPI-PF6 (diphenyliodonium hexafluorophosphate) at 0.2 and 0.4wt%, respectively. Formulations were tested as composite with the addition of 70wt% inorganic content consisting of barium borosilicate glass (0.7μm) and fumed silica mixed in 95 and 5wt%, respectively. All photocuring procedures were carried out by a mercury arc lamp filtered to 320-500nm at 800mW/cm. The experimental resin composites were tested for kinetics of polymerization and polymerization stress in real time. Flexural strength, elastic modulus, water sorption, and solubility were assessed according to ISO 4049. Biofilm formation was analyzed after 24h by luciferase assay. Data were statistically analyzed by one-way ANOVA and Tukey's test (α≤0.05).
RESULTS
In general, the addition of 2EMATE-BDI into the formulations decreased the maximum rate of polymerization (RP), the degree of conversion at RP (DC at RP), and the final degree of conversion (final DC). However, these reductions did not compromise mechanical properties, which were comparable to the BT controls, especially after 7-day water incubation. The incorporation of 60wt% 2EMATE-BDI reduced water sorption of the composite. 2EMATE-BDI containing formulations showed reduction in polymerization stress of 30% and 50% in comparison to BT control and TEGDMA copolymerizations, respectively. Biofilm formation was similar among the tested groups.
SIGNIFICANCE
The use of the newly synthesized diurethane dimethacrylate as co-monomer in dental resin composite formulations seems to be a promising option to develop polymers with low-shrinkage and potentially decreased water degradation.
Topics: Bisphenol A-Glycidyl Methacrylate; Composite Resins; Elastic Modulus; Materials Testing; Methacrylates; Polyethylene Glycols; Polymerization; Polymethacrylic Acids
PubMed: 32402514
DOI: 10.1016/j.dental.2020.04.009 -
Nature Communications Nov 2022As agriculture strives to feed an ever-increasing number of people, it must also adapt to increasing exposure to minute plastic particles. To learn about the...
As agriculture strives to feed an ever-increasing number of people, it must also adapt to increasing exposure to minute plastic particles. To learn about the accumulation of nanoplastics by plants, we prepared well-defined block copolymer nanoparticles by aqueous dispersion polymerisation. A fluorophore was incorporated via hydrazone formation and uptake into roots and protoplasts of Arabidopsis thaliana was investigated using confocal microscopy. Here we show that uptake is inversely proportional to nanoparticle size. Positively charged particles accumulate around root surfaces and are not taken up by roots or protoplasts, whereas negatively charged nanoparticles accumulate slowly and become prominent over time in the xylem of intact roots. Neutral nanoparticles penetrate rapidly into intact cells at the surfaces of plant roots and into protoplasts, but xylem loading is lower than for negative nanoparticles. These behaviours differ from those of animal cells and our results show that despite the protection of rigid cell walls, plants are accessible to nanoplastics in soil and water.
Topics: Animals; Polymers; Microplastics; Nanoparticles; Polymerization; Biological Transport; Water; Arabidopsis
PubMed: 36450796
DOI: 10.1038/s41467-022-35066-y -
Clinical Oral Investigations Jul 2022To investigate the chemical (degree of conversion (DC)) and mechanical properties (Martens hardness (HM), elastic indentation modulus (E), and biaxial flexural strength...
OBJECTIVES
To investigate the chemical (degree of conversion (DC)) and mechanical properties (Martens hardness (HM), elastic indentation modulus (E), and biaxial flexural strength (BFS)) of four dual-polymerizing resin composite core build-up materials after light- and self-polymerization.
MATERIALS AND METHODS
Round specimens with a diameter of 12 mm and a thickness of 1.5 mm were manufactured from CLEARFIL DC CORE PLUS (CLE; Kuraray), core·X flow (COR; Dentsply Sirona), MultiCore Flow (MUL; Ivoclar Vivadent), and Rebilda DC (REB; VOCO) (N = 96, n = 24/material). Half of the specimens were light-polymerized (Elipar DeepCure-S, 3 M), while the other half cured by self-polymerization (n = 12/group). Immediately after fabrication, the DC, HM, E, and BFS were determined. Data was analyzed using Kolmogorov-Smirnov, Mann-Whitney U, and Kruskal-Wallis tests, Spearman's correlation, and Weibull statistics (p < 0.05).
RESULTS
Light-polymerization either led to similar E (MUL; p = 0.119) and BFS (MUL and REB; p = 0.094-0.326) values or higher DC, HM, E, and BFS results (all other groups; p < 0.001-0.009). When compared with the other materials, COR showed a high DC (p < 0.001) and HM (p < 0.001) after self-polymerization and the highest BFS (p = 0.020) and Weibull modulus after light-polymerization. Positive correlations between all four tested parameters (R = 0.527-0.963, p < 0.001) were found.
CONCLUSIONS
For the tested resin composite core build-up materials, light-polymerization led to similar or superior values for the degree of conversion, Martens hardness, elastic indentation modulus, and biaxial flexural strength than observed after self-polymerization. Among the tested materials, COR should represent the resin composite core build-up material of choice due to its high chemical (degree of conversion) and mechanical (Martens hardness, elastic indentation modulus, and biaxial flexural strength) properties and its high reliability after light-polymerization. The examined chemical and mechanical properties showed a positive correlation.
CLINICAL RELEVANCE
The chemical and mechanical performance of dual-polymerizing resin composite core build-up materials is significantly affected by the chosen polymerization mode.
Topics: Composite Resins; Flexural Strength; Hardness; Materials Testing; Polymerization; Reproducibility of Results; Stress, Mechanical; Surface Properties
PubMed: 35344103
DOI: 10.1007/s00784-022-04455-4 -
Biophysical Journal Aug 2020We studied actin filament polymerization and nucleation with molecular dynamics simulations and a previously established coarse-grained model having each residue...
We studied actin filament polymerization and nucleation with molecular dynamics simulations and a previously established coarse-grained model having each residue represented by a single interaction site located at the C atom. We approximate each actin protein as a fully or partially rigid unit to identify the equilibrium structural ensemble of interprotein complexes. Monomers in the F-actin configuration bound to both barbed and pointed ends of a short F-actin filament at the anticipated locations for polymerization. Binding at both ends occurred with similar affinity. Contacts between residues of the incoming subunit and the short filament were consistent with expectation from models based on crystallography, x-ray diffraction, and cryo-electron microscopy. Binding at the barbed and pointed end also occurred at an angle with respect to the polymerizable bound structure, and the angle range depended on the flexibility of the D-loop. Additional barbed end bound states were seen when the incoming subunit was in the G-actin form. Consistent with an activation barrier for pointed end polymerization, G-actin did not bind at an F-actin pointed end. In all cases, binding at the barbed end also occurred in a configuration similar to the antiparallel (lower) dimer. Individual monomers bound each other in a short-pitch helix complex in addition to other configurations, with several of them apparently nonproductive for polymerization. Simulations with multiple monomers in the F-actin form show assembly into filaments as well as transient aggregates at the barbed end. We discuss the implications of these observations on the kinetic pathway of actin filament nucleation and polymerization and possibilities for future improvements of the coarse-grained model.
Topics: Actin Cytoskeleton; Actins; Cryoelectron Microscopy; Cytoskeleton; Polymerization
PubMed: 32668234
DOI: 10.1016/j.bpj.2020.06.019 -
International Journal of Molecular... Dec 2020This review presents the latest developments in (bio)degradable approaches and functional aliphatic polyesters and polycarbonates prepared by typical ring-opening... (Review)
Review
This review presents the latest developments in (bio)degradable approaches and functional aliphatic polyesters and polycarbonates prepared by typical ring-opening polymerization (ROP) of lactones and trimethylene carbonates. It also considers several recent innovative synthetic methods including radical ring-opening polymerization (RROP), atom transfer radical polyaddition (ATRPA), and simultaneous chain- and step-growth radical polymerization (SCSRP) that produce aliphatic polyesters. With regard to (bio)degradable approaches, we have summarized several representative cleavable linkages that make it possible to obtain cleavable polymers. In the section on functional aliphatic polyesters, we explore the syntheses of specific functional lactones, which can be performed by ring-opening copolymerization of typical lactone/lactide monomers. Last but not the least, in the recent innovative methods section, three interesting synthetic methodologies, RROP, ATRPA, and SCSRP are discussed in detail with regard to their reaction mechanisms and polymer functionalities.
Topics: Biodegradable Plastics; Chemistry Techniques, Synthetic; Polyesters; Polymerization
PubMed: 33339183
DOI: 10.3390/ijms21249581 -
Dental Materials Journal Nov 2022This study investigated transmittance changes during photo-polymerization of composites in real-time. The transmittance changes of one conventional micro-hybrid, three...
This study investigated transmittance changes during photo-polymerization of composites in real-time. The transmittance changes of one conventional micro-hybrid, three conventional nano-hybrid, and four bulk-fill composites were measured before, during, and after photo-polymerization, and the maximum rate of transmittance change was compared with that of polymerization shrinkage. A significant difference in transmittance of composite between before and after photo-polymerization was observed. The transmittance of composites except for one bulk-fill composite increased during photo-polymerization. There was a correlation between the maximum rate of transmittance change and the maximum rate of polymerization shrinkage. The transmittance analysis of composites gives very important information to know for the final aesthetic restoration and allows to evaluate polymerization kinetics.
Topics: Polymerization; Composite Resins; Materials Testing; Esthetics, Dental; Kinetics
PubMed: 35858790
DOI: 10.4012/dmj.2022-009 -
Indian Journal of Dental Research :... 2019The study aimed to compare the effect of different materials, thicknesses, and polymerization methods and cycles, on the surface porosity of acrylic denture base resins.
PURPOSE
The study aimed to compare the effect of different materials, thicknesses, and polymerization methods and cycles, on the surface porosity of acrylic denture base resins.
MATERIALS AND METHODS
Conventional heat-polymerized polymethyl methacrylate (PMMA) and specially designed acrylic resin (Acron MC) were used to make 84 rectangular samples. They were divided into three groups to evaluate and compare the polymerization techniques, curing cycles, and thicknesses of the two denture base materials (28 samples each). Group A contained PMMA samples polymerized using water bath method (control group); Group B contained Acron MC samples polymerized by microwave method, and Group C contained PMMA samples polymerized by microwave method. Each group was further divided based on sample thickness and polymerization cycles. Each sample was scanned for surface porosity and area of each pore was measured using optical microscope. Data was analyzed using ANOVA, Bonferroni, and student t-tests. Unpaired student t-test was performed to compare the means of surface porosity with polymerization cycles and thicknesses among the groups. The power of study was kept at 80%.
RESULTS
Group C showed highest mean % of porosity depending on method of polymerization, different polymerization cycles (short and long) and polymerization cycles within the group. Group B showed the highest mean % of porosity depending on thickness and thickness within the groups.
CONCLUSIONS
Microwavable acrylic resin polymerized by microwave energy exhibited statistically insignificant increase in porosity when compared to conventional heat cured acrylic resin by water bath method. Conventional acrylic resin polymerized by microwave energy exhibited high statistically significant porosity irrespective of sample thickness. There was statistically insignificant increase in porosity depending on sample thickness irrespective of material and method of polymerization.
Topics: Denture Bases; Humans; Materials Testing; Polymerization; Polymethyl Methacrylate; Porosity
PubMed: 31745057
DOI: 10.4103/ijdr.IJDR_170_16 -
Molecules (Basel, Switzerland) Oct 2023Molecularly imprinted polymers (MIPs) have gained significant attention as artificial receptors due to their low cost, mild operating conditions, and excellent... (Review)
Review
Molecularly imprinted polymers (MIPs) have gained significant attention as artificial receptors due to their low cost, mild operating conditions, and excellent selectivity. To optimize the synthesis process and enhance the recognition performance, various support materials for molecular imprinting have been explored as a crucial research direction. Yeast, a biological material, offers advantages such as being green and environmentally friendly, low cost, and easy availability, making it a promising supporting substrate in the molecular imprinting process. We focus on the preparation of different types of MIPs involving yeast and elaborate on the specific roles it plays in each case. Additionally, we discuss the advantages and limitations of yeast in the preparation of MIPs and conclude with the challenges and future development trends of yeast in molecular imprinting research.
Topics: Molecularly Imprinted Polymers; Saccharomyces cerevisiae; Polymers; Polymerization; Molecular Imprinting
PubMed: 37894582
DOI: 10.3390/molecules28207103 -
International Journal of Molecular... May 2022Amidst growing technological advancements, newer denture base materials and polymerization methods have been introduced. During fabrication, certain mechanical... (Review)
Review
Amidst growing technological advancements, newer denture base materials and polymerization methods have been introduced. During fabrication, certain mechanical properties are vital for the clinical longevity of the denture base. This systematic review aimed to explore the effect of newer denture base materials and/or polymerization methods on the mechanical properties of the denture base. An electronic database search of English peer-reviewed published papers was conducted using related keywords from 1 January 2011, up until 31 December 2021. This systematic review was based on guidelines proposed by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The search identified 579 papers. However, the inclusion criteria recognized 22 papers for eligibility. The risk of bias was moderate in all studies except in two where it was observed as low. Heat cure polymethyl methacrylate (PMMA) and compression moulding using a water bath is still a widely used base material and polymerization technique, respectively. However, chemically modified PMMA using monomers, oligomers, copolymers and cross-linking agents may have a promising result. Although chemically modified PMMA resin might enhance the mechanical properties of denture base material, no clear inferences can be drawn about the superiority of any polymerization method other than the conventional compression moulding technique.
Topics: Denture Bases; Materials Testing; Polymerization; Polymers; Polymethyl Methacrylate
PubMed: 35628546
DOI: 10.3390/ijms23105737