Mechanical properties of carbon fibre reinforced composites modified with star-shaped butyl methacrylate

This article presents the possibility of strength improvement and energy absorption of carbon fibre reinforced polymer composites by matrix modification. In this study, the mechanical properties of bisphenol-A epoxy matrix and carbon fibre reinforced polymer composites were modified with four different wt.% of star-shaped polymer n-butyl methacrylate (P n-BMA) block glycidyl methacrylate (PGMA). The tensile strength of the epoxy with 1 wt.% star-shaped polymer showed 128% increase in comparison to unmodified epoxy samples. Two different wt.% were then used for the modification of carbon fibre-reinforced polymer composite samples. Tensile tests and low-velocity impact tests were conducted for characterising modified samples. Tensile test results performed showed a slight improvement in the tensile strength and modulus of the composite. Low-velocity impact tests showed that addition of 1 wt.% star-shaped polymer additives increase composite energy absorption by 53.85%, compared to pure epoxy composite specimens. Scanning electron microscopy (SEM) analysis of post-impact specimens displays fracture modes and bonding between the matrix and fibre in the composites. These results demonstrate the potential of a novel star-shaped polymer as an additive material for automotive composite parts, where energy absorption is significant.

Insertion of Degradable Thioester Linkages into Styrene and Methacrylate Polymers

The thionolactone 3,3-dimethyl-2,3-dihydro-5H-benzo[e][1,4]dioxepine-5-thione (DBT) is shown to homopolymerize and, for the first time, copolymerize with styrene and methacrylates, introducing degradable thioester backbone functionality. The rapid copolymerization with styrene was exploited to produce copolymers through free-radical polymerization in a starve-fed semi-batch setup. The copolymerization of DBT with tert-butyl methacrylate under RAFT conditions was hypothesized to involve selective retardation of DBT-terminal chains that led to a more uniform distribution of degradable thioester linkages between chains. Surprisingly, the aminolysis of DBT homopolymers was accompanied by the intramolecular ether cleavage within the primary degradation product leading to the formation of 2,2-dimethylthiirane and salic-ylamides.

Fluoroponytailed Ionic Liquids as Co-Porogens for Poly(butyl methacrylate-co-ethylene dimethacrylate) Monolithic Supports for Thin Layer Chromatography

Porous layered monolithic substrates of poly(butyl methacrylate-co-ethylene dimethacrylate) were synthesized via UV initiated free radical polymerization in presence of fluoroponytailed ionic liquids as co-porogenic constituents. The effects of the type...

Influence of Different Ester Side Groups in Polymers on the Vapor Phase Infiltration with Trimethyl Aluminum

The vapor phase infiltration (VPI) process of trimethyl aluminum (TMA) into poly(4-acetoxystyrene) (POAcSt), poly(nonyl methacrylate) (PNMA) and poly(tert-butyl methacrylate) (PtBMA) is reported. Depth-profiling X-ray photoelectron spectroscopy (XPS) measurements are used...

Novel Amphiphilic Polyfluorene-Graft-(Polymethacrylic Acid) Brushes: Synthesis, Conformation, and Self-Assembly

Novel polyfluorene polymer brushes with polymethacrylic acid side chains were obtained by atom transfer radical polymerization (ATRP) and activator generated by electron transfer (AGET) ATRP of tert-butyl methacrylate on polyfluorene multifunctional macroinitiator, followed by protonolysis of the tert-butyl groups of the side chains. Kinetics of polymerization and molecular weights were fully characterized. These polymer brushes luminesce in the blue region of the spectrum with high quantum yields (0.64–0.77). It was shown that the luminescence intensity of polymer brushes is higher than the luminescence intensity of the macroinitiator (0.61). Moreover, due to their amphiphilic nature, they can form unimolecular micelles when an alcohol solution of the polymer brush is injected into water. These properties can potentially be used in drug delivery and bioimaging.

Transparency- and Repellency-Enhanced Acrylic-Based Binder for Stimuli-Responsive Road Paint Safety Improvement Technology

In the current study, an acrylic polymer binder applicable to road signs was successfully developed by mixing various acrylic, acrylate-type, and photoinitiator-based monomer species at different acrylate series/silicone acrylate ratios. An amorphous acrylic monomer was used, and the distance between the polymers was increased to improve transparency. The binder was designed with the purpose of reducing the yellowing phenomenon due to resonance by excluding the aromatic ring structure, which is the main cause of yellowing. The optical properties of the binder were determined according to the content of n-butyl methacrylate/methyl methacrylate and the composition of the crosslinking agent in the formulation. Allyl glycidyl ether and dilauroyl peroxide were used to improve the yellowing problem of benzoyl peroxide, an aromatic photoinitiator. Adding a silicone-based trivalent acrylic monomer, 3-(trimethoxysilyl)propyl methacrylate (TMSPMA), was also found to have a significant effect on the transparency, shear properties, and water resistance of the binder. When 15 wt% TMSPMA was added, the best water repellency and mechanical properties were exhibited. The surface morphology of the improved binder and the peeling part were confirmed using field emission scanning electron microscopy. The acrylic polymer developed in this study can be applied in the coating and adhesive industries.

Flash nanoprecipitation for the production of endosomolytic polymersomes for cytosolic drug delivery

The delivery of biomacromolecular drugs to cytosolic targets has been a long-standing engineering challenge due to the presence of multiple biological barriers including cellular and endosomal membranes. Although many promising carriers designed to facilitate endosomal escape have been developed, the clinical translation of these carriers is often limited by complex production processes that are not amenable to scaled-up manufacturing. In this study, we employed flash nanoprecipitation (FNP) for the rapid, scalable, and reproducible assembly of nanocarriers composed of the pH-responsive, endosomolytic diblock copolymer poly[(ethylene glycol)x-block-[((2-diethylamino) ethyl methacrylate)0.6-co-(butyl methacrylate)0.4]y (PEG-b-DEAEMA-co-BMA). We found that varying the second block molecular weight, while holding the first block molecular weight constant, significantly influenced nanoparticle self-assembly and hence nanocarrier properties and function – including drug encapsulation, endosomolytic capacity, cytotoxicity, and in vitro activity of a cytosolically-active drug cargo, a cyclic dinucleotide (CDN) stimulator of interferon genes (STING) agonist. We found that while increasing second block molecular weight enhanced the capacity of nanocarriers to induce endosomal destabilization, larger second block molecular weights also lead to increased cytotoxicity, increased particle size and heterogeneity, increased the encapsulation efficiency of small (<0.5 kDa) hydrophilic drugs, decreased the encapsulation efficiency of large (10 kDa) hydrophilic biomacromolecules, and decreased long-term particle stability. Collectively, these results demonstrate the utility of FNP for the rapid and scalable production of uniform PEG-b-DEAEMA-co-BMA nanocarriers and implicate an optimal hydrophilic mass fraction for balancing desirable nanoparticle properties with cytosolic cargo delivery efficiency.