A robust method for the analysis of cyclic siloxanes D4 to D25 via on-line coupled HPLC-GC-FID is presented to provide reliable data for the migration of these oligomers, in particular, into fatty foods. Post-cured and non-post-cured platinum silicone moulds were tested under different conditions of repeated use (baking at 180 °C, 15 min; chocolate preparation at max. 45 °C, 2 h). Overall siloxane migration analysis via 1H-NMR as well as oligomer profiling in the materials via GC-FID were performed to obtain a comprehensive picture. Maximum transfer was determined into shortcrust pastry for D7 (29.9 mg/kg food, 1st cycle), which was 6.4% of its initial content in the non-post-cured material. Noteworthily, under hot-use conditions, volatile siloxanes from non-post-cured materials were released mainly into ambient air, and less into food (e.g. during five cycles of baking, approx. 1% of the initial D5 amount migrated, but approx. 98% were evaporated). Post-curing sufficiently reduces migration of siloxanes < 1000 Dalton (e.g. sum D4 to D13, shortcrust pastry, 153 mg/kg from non-post-cured and 9.5 mg/kg from post-cured mould, 1st cycle). However, migration of oligomers > D20 is almost independent of post-curing and can cause an issue in terms of the overall migration limit of 60 mg/kg (e.g. 167 mg/kg total siloxanes migrated into shortcrust pastry, 3rd cycle). Also, at moderate temperatures during chocolate preparation, significant migration was determined (e.g. 21.5 mg/kg total siloxanes, 3rd cycle). In terms of risk assessment of multiple use articles made from silicone, the use of food simulant D2 can cause significant underestimations in the 3rd cycle, because of an almost total extraction during the first two migration cycles. Therefore, the assessment of silicone articles should be based on real food application testing - an appropriate method for this is presented using HPLC-GC-FID.

Many properties of polymers are well-described by a few simple concepts, such as a coarse-grained chain of N beads. Here, we study the motion of the two end-blocks. To observe end-block relaxation, we chose a molecular weight high enough to avoid effects by chemical end-groups but still avoid entanglement effects. We take advantage of molecular interactions, molecular weight, isotopic sensitivity, and length-scale information encoded in the momentum transfer of neutron spin echo spectroscopy to arrive at a more holistic picture of the contributions of the end-blocks to the polymer dynamics of unentangled chains. Our model polymer melt, poly(dimethyl siloxane), PDMS, has weak intermolecular interactions, leading to a lower sub-diffusion contribution. The experimental results are in excellent agreement with the theory and indicate the appearance of two regions that show terminal bead relaxation in addition to the well-known sub-diffusion of the center of mass, the center of mass diffusion, and (Rouse) segmental relaxation. The quantitative analysis shows terminal beads with a length equivalent to 1-2 Kuhn segments that relax twice as fast as beads in the middle of the polymer chain. The time-dependence of the mean square displacement is in quantitative agreement with simulations with terminal bead segmental relaxation (t0.65) and sub-Rouse relaxation of end-beads (t0.57) in the intermediate range between sub-diffusion (t0.8) and center of mass diffusion (t1). For the specific example of a polymer with 143 segments, 11 end-segments define one end-block with faster dynamics, whereas the remaining 121 belong to the middle block. Segments in the end block exhibit faster dynamics compared to those in the middle block. Both the end block and the middle block consist of multiple segments. Therefore, analyzing the data requires considering both concepts to effectively describe the dynamics of polymer chains.

FeSiAl soft magnetic composites with hybrid insulation layers achieved by thermal decomposition of dimethyl diphenyl siloxane resin

Enhanced dielectric properties of poly(dimethyl siloxane) based composites with modified MXene

ABSTRACT Silicon is a promising anode material for lithium‐ion batteries because of its high theoretical capacity. However, their practical application is hindered by substantial volume expansion during lithiation/delithiation, which leads to mechanical degradation and capacity fading. To address this challenge, we propose a stress‐dissipative binder system based on UV‐induced cross‐linking of viscoelastic poly(dimethyl siloxane) (PDMS) with rigid linear poly(acrylic acid) (PAA). The resulting PAA–PDMS binder can reversibly deform and recover in response to external stress due to the flexible siloxane backbone in PDMS, thereby accommodating the substantial volume expansion of Si electrode. Furthermore, the amphiphilic nature of the PDMS molecule increases its affinity for both carbon and Si particles, resulting in enhanced mechanical integrity of the Si electrode. These inherent characteristics of PDMS can effectively compensate for the rigidity of PAA, resulting in a well‐balanced binder system tailored for Si electrodes. Consequently, the PAA–PDMS electrode exhibited a discharge capacity of 2072.68 mAh g −1 after 100 cycles at 0.5 C−rate, whereas the PAA−based electrode reached failure after only 70 cycles. Post‐mortem analyses reveal that the improved electrochemical performance of the PAA–PDMS electrode arises from its ability to mitigate Si electrode degradation by suppressing volume expansion and stabilizing the electrode–electrolyte interface.

This study presents the development of dissolving levonorgestrel-loaded microneedles (LMNs) incorporating a chitosan–β-glycerophosphate thermogelling system for sustained transdermal delivery of levonorgestrel (LNG) as a contraceptive. Polyvinylpyrrolidone K90 and Dextran 40 were included to enhance mechanical strength and controlled drug release. LMNs fabricated using poly dimethyl siloxane moulds exhibited uniform, sharp structures as confirmed by scanning electron microscopy. Fourier transform infra-red and X-ray diffraction analyses demonstrated chemical compatibility and physical stability of LNG within the matrix. The optimised LMNs showed significant mechanical strength (p < 0.05) and high insertion efficiency (F = 17.83, p = 3.03 × 10−8) across Parafilm® layers and fully dissolved within 30 min in porcine skin. Ex vivo studies revealed sustained LNG release (70.86% ± 0.42%) over 48 h, outperforming a topical gel (42.33% ± 0.91%). Drug release followed first-order kinetics (R 2 = 0.996) and non-Fickian diffusion (n = 0.79), indicating a combined diffusion–erosion mechanism. In vivo evaluation in Wistar rats showed significant contraceptive efficacy, with reduced implantation sites (0.5 ± 0.55) and uterine thickness (3.66 ± 0.51 mm; p < 0.0001), comparable to oral LNG. These results highlight LMNs as a promising, minimally invasive platform for long-acting transdermal contraception, offering improved bioavailability, patient compliance and therapeutic effectiveness.

ABSTRACTBase‐catalyzed ring opening polymerization (ROP) of cyclosiloxane D3 was conducted using various alcohols as initiators to produce end‐group functional poly(dimethylsiloxane)(PDMS). To demonstrate the concept for vesicle formation, a poly(ethylene glycol)‐b‐poly(dimethyl siloxane)‐b‐poly(ethylene glycol) (PEG‐PDMS‐PEG) triblock copolymer, where one PEG block was attached through a stable carbosilane bond while the other PEG was coupled through a hydrolytically labile silyl ether linkage was prepared. Non‐catalyzed hydrolysis of this copolymer in aqueous suspension led to a slow transformation of the triblock into the corresponding diblock copolymer and, conversely, to the transformation of the initially formed large aggregates into well‐defined vesicles with a diameter of less than 100 nm over one week. In contrast, a control triblock copolymer with the same composition but without the silyl ether bond did not change morphology.

In the current state of the art of grating designs, compositions involving different metals and polymers have not been adequately addressed. Our study aims to fill this gap by investigating the influence of varying material compositions on polarization properties. To address this issue, we computed the refractive indices of mixtures of gold, silver, and poly(dimethyl siloxane) (PDMS) using the Bruggeman Theory, and simulated optical transmission and reflection of the gratings made of these hybrids. Our analysis revealed prominent peaks in the extinction coefficient at distinct wavelengths for various material ratios. Notably, our simulation results suggest the potential for fine-tuning the extinction coefficient within the range of 450-1000 nm. Furthermore, we demonstrate the attainment of polarization ratios of both 0 and 1 within the simulation environment. These outcomes offer the prospect of designing optical filters and polarizers targeted to specific wavelengths.

Cyclosporine A (CsA) is widely used to treat dry eye disease (DED), and ocular morbidity is on the rise and is a growing concern globally. However, several drug and formulation challenges, such as poor drug solubility, short pre-corneal residence time, and poor patient compliance, have limited the ocular bioavailability of CsA to < 5%. A CsA cyclodextrin-based ternary complex loaded dissolvable nano drug reservoir films were developed to overcome these limitations and efficiently manage DED. Drug-loaded nano-reservoir films were fabricated via lithography using silicone and poly (dimethyl siloxane) (PDMS) molds. Different physicochemical characterizations were performed to confirm the formation of stable CsA-cyclodextrin-based ternary complexes. Formation of nanoreservoirs on the films was confirmed using SEM and AFM. Optimized CsA-complex-loaded nano-reservoir films were evaluated for in vitro drug release, ex vivo corneal permeation, and in vivo precorneal retention. Preclinical efficacy studies were performed to assess the efficacy of CsA-complex-loaded nano-reservoirs in an experimental dry-eye mouse model. Physicochemical characterization confirmed the formation of a stable complex and the improved solubility of CsA. In vitro release and ex vivo permeation studies indicated a controlled drug release and improved permeation, respectively. Furthermore, tear volume measurement and corneal damage assessment using slit-lamp imaging suggested decreased dry eye symptoms, significantly increasing tear volume in the drug-loaded nano-reservoir-treated group. Moreover, histopathological studies corroborated the tear volume and slit-lamp imaging results, with reduced inflammation and neovascularization. The poorly water-soluble drug with cyclodextrin complex incorporated nanoreservoir films presents a potential alternative for managing various ocular diseases.Graphical

Blending of thermoplastic polyurethane (TPU) with poly dimethyl siloxane rubber (PDMS) is an attractive approach, where one can combine the strength, toughness and biocompatibility of TPU with flexibility, inertness, high temperature resistance, low temperature flexibility and biocompatibility of PDMS. But the control of the factors determining the overall properties of such a blend like mixing time, temperature and rotor speed is difficult. Hence, an attempt has been made to optimize these processing parameters using statistical technique as per Taguchi. Four factors and three levels were chosen for carrying out the analysis using L9 Orthogonal Array as per Taguchi methodology. Tensile strength and impact strength of the blends under different processing conditions were evaluated as the quality characteristics. Analysis of Variance (ANOVA) was used in determining the significance of factors. The levels of significant factors were optimized using Signal to Noise ratio. It was found that a balance between the two properties were obtained when melt blending was carried out at 190 ̊C at 100 rpm rotor speed for 9 minutes for a blend of TPU with PDMS in the proportion of 70/30 by volume. Confirmatory tests were carried out to verify the optimized formulation. Blend morphology studies revealed that PDMS phase gets uniformly dispersed in a matrix of TPU. These blends are expected to be utilized for biomedical applications such as surgical implants and biomedical devices.

The effect of rGO/SiO2 hybrid filler on Lap shear strength of Polyurethane adhesive having Poly (dimethyl siloxane) (PDMS)

Anti-icing and antibacterial super-hydrophobic poly(dimethyl siloxane) coatings modified with silica, TiO2, Ag3PO4, and CuO nanoparticles

We report the synthesis and photoresponsivity of precisely designed liquid star-shaped poly(dimethyl siloxane) (PDMS) with anthracene end groups. Owing to the efficient end-linking of the flexible PDMS arms upon the first UV irradiation (λ = 365 nm, UV365), the storage modulus (G') increased from 4.7 Pa to 119 kPa (>25 000-fold), and the physical state became a rubbery solid. Subsequent irradiation with UV light at a shorter wavelength (λ = 254 nm, UV254) decreased G' toward the photostationary state, and viscoelasticity modulation was achieved between the two photostationary states under solvent-free conditions.

Poly(dimethyl siloxane) bimodal brush: Simple method of preparation and performance enhancement of omniphobic coatings

The significance of multiple emulsions lies in their capacity to serve as precision carriers that simultaneously encapsulate, protect, and co-deliver active substances, enabling critical functions including targeted delivery, sustained release, and enhanced ingredient stability. This study presents a scalable fabrication approach for preparing multiple emulsions via poly(dimethyl siloxane) (PDMS) microfluidic devices without requiring additional fluids or surface-modified coatings. We achieve controllable modulation of wettability on PDMS chip surfaces through localized plasma treatment following partial masking. Then, we successfully prepare single, double, and triple emulsions, demonstrating the scalability of this strategy for generating complex emulsions. Subsequently, using double emulsions as a model system, we systematically investigate the flow rate conditions required for their sustained generation. Finally, to achieve precise control over emulsion droplet size, we further explore the influence of flow rate parameters for the outer phase, middle phase, and inner phase on the size of double emulsions. This foundational work lays the groundwork for future research to optimize the preparation methods for multiple emulsions and develop stimuli-responsive systems for uses such as drug delivery and food preservation.

Abstract Modification of a surface with polymer brushes has emerged as an effective approach to tune the properties of a substrate. Brushes grown from an inimer‐containing cross‐linkable polymer coating provide significant advantages compared to other “grafting‐from” methods, such as improved stability, increased grafting density, and the potential to control the grafting density. So far, the inimer coating method has only been applied for surface‐initiated controlled radical polymerizations. In this work, an approach is presented for the fabrication of a stable cross‐linked ultra‐thin polymer coating containing hydroxyl groups which serve as initiating sites for surface‐initiated ring‐opening polymerization (SI‐ROP). The polymers used for the fabrication of the coatings consist of 2‐((tetrahydro‐2H‐pyran‐2‐yl)oxy)ethyl methacrylate (THPEMA), a small fraction of a cross‐linkable unit, and a diluent styrene. Three coatings with varying THPEMA and styrene content are fabricated, and poly(dimethyl siloxane) (PDMS) and poly(caprolactone) (PCL) brushes are grown by SI‐ROP of hexamethylcyclotrisiloxane (D3), and ε‐caprolactone respectively. The brushes are characterized by atomic force microscopy (AFM), X‐ray photoelectron spectroscopy (XPS), static contact angle measurements, ellipsometry and size exclusion chromatography (SEC). The results demonstrate a well‐controlled ROP of D3 and ability to control grafting density by tuning the THPEMA content of the coatings.

To establish an animal model of form deprivation amblyopia based on a simulated cataract intraocular lens (IOLs). Poly(dimethyl siloxane)-SiO2 thin films (PSF) with different degrees of opacity as IOL materials were prepared. The light transmission of the PSF-IOL was measured, and its in vitro biosafety was determined by cell counting kit (CCK)-8 assay using the HLEC-B3 cell line and ARPE-19 cell line. Subsequently, the in vivo safety was determined by implanting the PSF-IOL with 10% wt SiO2 into the right eyes of New Zealand white rabbits (PSF-IOL group), and compared with two control groups: contralateral comparison group and normal control (NC) group (Contralateral comparison group: the fellow eye; NC group: a group of binocular normal rabbits without intervention). The flash visual-evoked potentials (F-VEPs) were measured to verify amblyopia. PSFs containing 0, 2%, and 10% wt SiO2 were successfully constructed. The 0 SiO2 PSF was transparent, while the 10% wt SiO2 PSF was completely opaque. It was found that PSF did not induce unwanted cytotoxicity in HLECs and ARPE19 cells in vitro. In vitro, PSF-IOL with 10% wt SiO2 was also non-toxic, and no significant inflammation or structural changes occurred after four weeks of PSF-IOL implantation. Finally, our IOL-simulated congenital cataract rabbit detected by F-VEPs suggested tentative amblyopia. A PSF-IOL that mimics cataracts is created. A novel form deprivation model is created by the IOL-simulated congenital cataract rabbit. It can be developed fast and stable and holds great potential for future study.

Brush-like graft copolymers (A-g-B), in which linear A-blocks are randomly grafted onto the backbone of a brush-like B-block, exhibit intense strain-stiffening and high mechanical strength on par with load-bearing biological tissues such as skin and blood vessels. To elucidate molecular mechanisms underlying this tissue-mimetic behavior, in situ synchrotron X-ray scattering was measured during uniaxial stretching of bottlebrush- and comb-like graft copolymers with varying densities of poly(dimethyl siloxane) and poly(isobutylene) side chains. In an undeformed state, these copolymers revealed a single interference peak corresponding to the average spacing between the domains of linear A-blocks arranged in a disordered, liquid-like configuration. Under uniaxial stretching, the emergence of a distinct four-spot pattern in the small-angle region indicated the development of long-range order within the material. According to the affine deformation of a cubic lattice, the four-spot pattern's interference maxima correspond to 110 reflections upon stretching along the [111] axis of the body-centered unit cell. The experimental findings were corroborated by computer simulations of dissipative particle dynamics that confirmed the formation of a bcc domain structure.

PurposeIn vitro millifluidic cultures with perfusion are essential tools to analyse and understand the interactions between cells, their matrix and multi-cell populations. The purpose of this paper is to focus on the design and development of a 3D-printed template that can be used for fabrication of a clear view poly (dimethyl siloxane) (PDMS) device. The major objective is to obtain a transparent device prototype that allows perfusion culture of two cell types for multiple days that can be imaged using laser scanning confocal microscopy.Design/methodology/approachThe authors used a two-step approach for achieving the final geometric structure at a faster timeline and lower cost. The first part focuses on comparing the fidelity of the printing templates using fused deposition modelling (FDM) and stereolithography (SLA) printers for a range of dimensions. They then show that the complex geometry chip with connection chambers can be printed using low resolution low cost FormLab SLA printer. The final optimized design was then printed using high-resolution Projet 6000 SLA printer to obtain smoother structures.FindingsIn this work, the authors have shown that the FormLab SLA printer yields significantly lower error for printing complex design geometries as compared to FDM printer. Result shows that FormLab printer can be used to achieve a minimum dimension of 0.5 mm. They then use the printer to optimize the device dimension for the culture chip which requires several iterations of printing and experimenting. They showed the two-step protocol of printing the optimized template in a high-resolution SLA printer and further fabricating a clear view millifluidic PDMS device that is compatible confocal microscopy imaging. They used this culture chip for perfusion culture of two cell type, and the controlled fluidic exchange between the two chambers led to the formation of neuroglia junction.Originality/valueOne of the major bottlenecks for obtaining complex geometry in mili/microfluidic device by 3D printing is the need of multiple iterations on printing. This makes the tuning of dimension significantly expensive. Another challenge is to obtain a smooth surface of PDMS that leads to a leak proof clear view device compatible for laser based confocal imaging. The combination of two printers plays a crucial role for the rapid prototyping of the imaging device with flow control. The proposed approach lowers the cost for prototyping of in vitro culture chip with complex geometries to improve on biological research demanding multi-chamber fluidic device.

Smudge-resistant antimicrobial ladder-like polysilsesquioxane coatings