Polymer Surface Roughness Research Articles

Plasma-chamber wall interaction and its impact on polymer deposition in inductively-coupled C4F8/Ar plasmas

Plasma processing chambers, key tools in semiconductor device fabrication, must be meticulously maintained to ensure tool-to-tool matching. Processing chamber walls are liable to contamination with fluorocarbon (CxFy) film, which acts as a source and/or sink for active species during plasma processes. This contamination potentially affects processing quality and alters the plasma properties, increasing deviations between processing chambers. However, quantitative studies on the impact of wall contamination on the substrate deposition outcomes have been limited. Additionally, spatially resolved investigations are crucial for understanding the plasma-wall interaction. Therefore, this study evaluated the influence of polymer (CxFy) film wall contamination on plasma deposition via various plasma diagnostics and surface analyses. When the chamber inner wall was coated with polymer film, the thickness, surface roughness, and chemical composition of the deposited film on the bottom substrate were more uniform. These results were linked to alterations in the uniformity of active species in the plasma, such as CF2 and F, resulting from interaction with the polymer film on the wall's surface. The C–Fx and C–CFx composition ratios in the wall-coated films dramatically reduced, indicating that this film supplied the depositing precursors to the plasma. These results suggest that controlling the chamber wall conditions is important to maintain tool-to-tool matching and modulate the processing performance.

Temperature-induced dielectric and electrical behavior of Cs/HPC-copper vanadate nanocomposites

This study investigates the effects of temperature exposure on the dielectric and electrical properties of Cs/HPC-copper vanadate nanocomposites. The results indicate a direct correlation between the increase in polymer surface roughness and the amount of incorporated copper vanadate nanoparticles. The real dielectric constant and imaginary dielectric constant exhibited a notable increase at lower frequencies, which was attributed to interfacial polarization. At higher frequencies, the decrease was due to space charge polarization. The incorporation of copper vanadate nanoparticles resulted in a significant enhancement of both the real dielectric constant and imaginary dielectric constant highlighting the crucial role of these nanoparticles in the electrical properties of the nanocomposites. The impedance (Z′) and impedance (Z′) measurements indicate a decrease in Z″ with increasing frequency and temperature, suggesting enhanced ionic conductivity and interfacial polarization. The Cole–Cole plots reveal that the dielectric relaxation process in the Cs/HPC-copper vanadate nanoparticles (NPs) follow the non-Debye model. The results provide insights into the charge-transport mechanisms in these nanocomposites and highlight the importance of temperature in controlling their electrical properties.

Effect of resin cement viscosities and surface roughness on shear bond strength of conditioned polymer infiltrated ceramic network

BackgroundHybrid ceramics bonding with the dentinal substrate is crucial for clinical success and longevity. To enhance adhesion, the surface of ceramic restorations is modified through various conditioning techniques AimEffect of Different Surface Conditioners Erbium-doped yttrium aluminum garnet (ER: YAG) laser and Low-level laser therapy (LLLT) activated Methylene blue (MB) on the surface roughness (Ra) and shear bond strength (SBS) of Polymer infiltrating ceramic network (PICN) discs bonded using different viscosity resin cement before and after thermal aging. Material and MethodsOne hundred and fifty human central incisors and one hundred and fifty-three PICN discs were prepared. PICN discs were randomly allocated into three groups based on the surface conditioning(n = 51) Group 1:10 % HF acid-S, Group 2: LLLT (MB), and Group 3: Er: YAG laser. Following conditioning Ra scores of ten samples were performed. Surface topography of samples was performed using a scanning electron microscope (SEM). Bonding of forty PICN discs from each conditioning group was performed with high (A) or low viscosity (B) dual-curing resin cement (n = 20 each). Each subgroup was divided into two cohorts and subjected to varying storage conditions. The SBS test and failure mode analysis were performed using a universal testing machine and stereomicroscope. Descriptive statistics of SBS and Ra for each group were analyzed using ANOVA and Tukey post hoc tests. HF acid-S attained the highest Ra scores. ResultsGroup 1A (HF-S+HIGH) samples achieved the highest SBS values at baseline. Group 3A, on the other hand, displayed the lowest bond score (Er: YAG laser+HIGH) after thermal aging. Intergroup comparison analysis at baseline unveiled that Group 1A and Group 1B (HF(S) + LOW) displayed no significant difference in their bond strength scores (p>0.05). Following artificial aging, it was observed that Group 2A (LLLT (MB) + HIGH) and Group 3A (Er:YAG laser + HIGH) ) presented comparable SBS(p > 0.05). Thermal aging decreased SBS significantly in all groups. PICN conditioned with HF-S results in high surface roughness. ConclusionPICN conditioned with HF acid with silane and bonded with low-viscosity resin cement to the dentinal substrate is preferable. Aging influences SBS.

Influence of Polymer Surface Roughness on the Fractions of Transmitted, Reflected and Absorbed Energy in Operation of Laser Transmission Welding

The study of energy fractions plays a fundamental role in laser joining operations: from their knowledge, it is possible to calculate the amount of laser beam energy that is effectively available during the formation of chemical and physical bonds, and how much energy is dissipated. This study examines semi-crystalline polymers of polyamide 6.6 (PA), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), and polypropylene (PP), semitransparent to light radiation, with the aim of studying the influence of surface roughness on the distribution of energy fractions, and in particular on the reflection portion. For this purpose, polymeric samples with different surface finishing were prepared and characterized by profilometric analysis. Subsequently, an experimental setup was implemented to directly measure the transmitted ratio, obtaining the reflected energy fraction from the Beer-Lambert law, and the absorbed ratio by energy balance. The results showed a decrease in the power transmitted by polymers subjected to surface treatment, due to an increase in the reflection fraction, a phenomenon particularly evident for PET, for which the reflection share increased from ~ 0.5% to ~ 15.3%, following P240 treatment. A lower influence was verified for PA and especially PTFE, due to a lower influence of the treatment on surface morphology. On the basis of the experimental results, it is hypothesised that roughening the lower section of the irradiated polymer could allow an increase in the total internal reflection fraction, favouring the joint at the interface point.Graphical

Influence of prophylactic fluoride agents on the color changes and surface roughness of polymer and rhodium coated nickel-titanium orthodontic archwires

The effect of fluoride use on the color change and surface characteristics of coated nickel and titanium (NiTi) orthodontic archwires was investigated. Epoxy resin, PTFE or rhodium-coated archwires were exposed to acidulated phosphate fluoride (APF) or sodium fluoride (NaF) or artificial saliva (AS), simulating three-month clinical trials. Color changes (∆E) were assessed using a laboratory spectrophotometer in the three-dimensional CIELab color space. The roughness (Ra) and surface structure of the archwires were examined using a non-contact profilometer and scanning electron microscopy (SEM), respectively. Data were analyzed using two-way and one-way variance (ANOVA) and post-hoc Bonferroni test (α=0.05). The average values of ∆E and Ra were the highest for epoxy-APF archwires and the lowest for rhodium-AS archwires. A significant relationship was found between the archwires surface treatment method and the ∆E and Ra values. After three months, greater changes in color and roughness were observed with APF than with AS.

Chemical and Morphological Modifications Induced by Argon Plasma Treatments on Fluorinated Polybenzoxazole Films.

Fluorinated photodefinable polymers are widely employed as re-distribution layers in wafer-level packaging to produce microelectronic devices because of their suitable low dielectric constant and moisture absorption, high mechanical toughness, thermal conductivity and stability, and chemical inertness. Typically, fluorinated photodefinable polybenzoxazoles (F-PBOs) are the most used in this field. In the present work, we investigated by atomic force microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy the morphological and chemical modifications induced by Ar plasma treatments on F-PBO films. This process, used to remove surface contaminant species, as well as increase the polymeric surface roughness, to improve the adhesion to the other components during electronic packaging, is a crucial step during the manufacturing of some microelectronic devices. We found that argon plasma treatments determine the wanted drastic increase of the polymer surface roughness but, in the presence of a patterned silver layer on F-PBO, needed for the fabrication of electric contacts in microelectronic devices, also induce some unwanted formation of silver fluoride species.

Biological magnetic ion exchange resin on advanced treatment of synthetic wastewater

In this work, three biological ion exchange systems and one biological activated carbon (BAC) system were established by employing magnetic ion exchange resin (MIEX), non-magnetic resin (NIEX), polystyrenic resin (DIEX) and granular activated carbon as the biocarrier for advanced treatment of wastewater. Dissolved organic carbon (DOC) removal of four systems all stabilized at about 84% due to biodegradation. The start-up period of bio-MIEX (nearly 40 d) was greatly shorter than that of others (nearly 190 d). Ibuprofen removal was ascribed to adsorption in the initial stage, which subsequently changed to the effect of biodegradation. After the start-up period, ibuprofen removal was nearly 100% (bio-MIEX), 60% (bio-NIEX), 61% (bio-DIEX) and 89% (BAC). According to the surface observation, ATP and protein measurement and metagenomic analysis, the superior performance of bio-MIEX could be attributed to its highest biological activity resulted from the presence of Fe3O4 rather than polymer matrix and surface roughness.

Effects of Cavity Thickness and Mold Surface Roughness on the Polymer Flow during Micro Injection Molding.

In micro injection molding, the cavity thickness and surface roughness are the main effects factors of polymer flow in the die designing and affect the quality of molded products significantly. In this study, the effects of cavity thickness and roughness of cavity surface were investigated mainly on polymer flow during molding and on the roughness of molded products. The parts were molded in the cavities with the thickness from 0.05 mm to 0.25 mm and surface roughness from Ra = 46.55 nm to Ra = 462.57 nm, respectively. The filling integrities and roughness replication ratio of molded parts were used to evaluate the statements of polymer flow and microstructure replication during micro injection molding, respectively. The results showed that the filling integrity changing trends in the thinner cavities were obviously different or even opposite to those in the thicker cavities with the changing of cavity surface roughness instead of single trend in the conventional studies. For each cavity surface roughness, the filling integrity showed an upward trend with the increasing cavity thickness. In different cavity thickness, the maximum gap of filling integrity was 23.76 mm, reaching 544.94% from 0.05 mm to 0.25 mm. Additionally, the surface roughness ratio was slightly smaller than one before, reaching the polymer surface roughness limit around Ra = 71.27 nm, which was decided by the nature of the polymer itself. This study proposed the references for the design and fabrication of mold cavities and parts, and saved time and cost in the actual product manufacturing.

Surface roughness prediction model in high-speed dry milling CFRP considering carbon fiber distribution

The surface roughness of carbon fiber-reinforced polymer (CFRP) components is extremely important because of the increasing demand for higher performance, reliability, and longer lifetime in aerospace and other manufacturing industries. However, the cutting mechanisms of CFRP are still unclear, which limits its formation mechanism prediction for surface roughness. Thus far, this study presents three action mechanisms in the CFRP machining process: accumulation bouncing on the matrix, impact effect on carbon fibers, and workpiece self-action. The workpiece self-action was reflected and calculated using the light rope model, which is new in CFRP machining. Furthermore, the formation mechanisms of surface roughness were first elucidated in the high-speed dry (HSD) milling of CFRP. An accurate surface roughness prediction model was theoretically formulated considering the kinematics, dynamics, and carbon fiber distribution. Surface roughness was expressed as the three-dimensional arithmetic mean height. The surface roughness prediction model was established and confirmed to have a high prediction accuracy of 90.05%, demonstrating that the distribution of carbon fibers was the main influencing factor of the surface roughness. Moreover, nonlinear regression analysis was used to clarify the effects of cutting parameters on the surface roughness, impact effect, and relationship between the surface roughness and impact effect. The study verified the feasibility of HSD milling CFRP, and it also provided guidance for breaking the low-speed machining limits by improving the machining process.

Experimental investigation on the interfacial shear bond performance of non-water reacting polymer and concrete

Non-water reacting polymer is widely used in the construction and trenchless rehabilitation of underground spaces and concrete pavement structures. The damage mechanism of interface between polymer and concrete is crucial, but is yet still unclear. In this study, Shear tests of the polymer-concrete composite specimens with different surface roughnesses and polymer densities were conducted, and the fitting model of the bond strength with the polymer density and surface roughness were derived. The failure characteristics of the composite specimens were studied by acoustic emission technology and the microstructure features of polymer in the edge, middle, and interface positions were analyzed by scanning electron microscope. The interface bond strength increased significantly with the increased of polymer density when the polymer density was larger than 0.15 g/cm3. For polymer-concrete composite specimens with different polymer densities and surface roughnesses, the failure modes of the specimens are quite different and the failure modes can be divided into polymer matrix failure, interface failure and concrete matrix failure. AE activity exists throughout the failure process of polymer-concrete specimen and is most significant in the final failure stage. The accumulative AE ringing counts and energy sharply increase indicated that the specimen is about to fail. The polymer cell structure at the interface and edge positions can be divided into three areas: high-density cell structure, belt-shaped continuous area and low-density cell structure area, and the interface polymer cell structures were affected by the polymer density and the interface roughness. The work provides a better understanding of the influencing factors, failure modes and damage mechanism of the bond performance between non-water reacting polymer and concrete.

Extreme Orientational Uniformity in Large-Area Floating Films of Semiconducting Polymers for Their Application in Flexible Electronics.

Layer-by-layer fabrication of uniformly oriented thin films over large areas by cost-effective solution-based approaches can open new horizons for the realization of high-performance organic circuits in various applications. In this work, fabrication of a large-area ≈40 cm2 film with uniform orientation is reported for poly(3,3‴-dialkylquaterthiophene) (PQT) using a unidirectional floating film transfer method (UFTM). Orientation characteristics and charge transport anisotropy were analyzed using polarized UV-vis spectral mapping and fabrication of bottom-gated organic field-effect transistors (OFETs) from different regions. Films were found to be highly oriented with an optical dichroic ratio of ca. 15. Orientation characteristics reveal that films were highly oriented along the width of the film, covering >70% of the area, and angle-dependent field-effect mobilities are in good agreement with the orientation of the polymer backbones. These highly oriented films resulted in charge transport anisotropy of 8.9. An array of bottom-gated OFETs fabricated along the length of single large-area (≈15 × 2.5 cm2) thin film demonstrated the average field-effect mobility of 0.0262 cm2/(V s) with a very narrow standard deviation of 12.6%. We also demonstrated that film thickness can be easily tuned from 5.6 to 45 nm by increasing the PQT concentration, and field-effect mobility is highly reproducible even when the film thickness is 10 nm. Microstructural characterization of the thus-prepared large-area thin films revealed the edge-on stacked polymer backbones and surface roughness of <1 nm as probed by grazing incidence X-ray diffraction and atomic force microscopy, respectively. Flexible OFETs with bottom-gate top-contact geometry were also fabricated, having average field-effect mobility of 0.0181 cm2/(V s). There was no considerable change in mobility after bending the flexible devices at different radii.

Studying the Structural and Morphological Properties of (PMMA) Film under D.C Discharge Plasma

In this paper, a lab-scale direct current (DC) glow discharges plasma system was used to adjust the surfaces of polymeric films. Characteristics of the plasma system have displayed under the discharge of three gasses (O2, N2 and Ar). DC-Plasma system has been used for the adjustment of polymethyl methacrylate surface as a function of treatment time and the types of gases. The modified surface was characterized in terms of crystal structure and surface morphology by the analysis of X-ray diffraction, scanning electron microscopy (SEM) and atomic force microscopy (AFM). A comparison between treated and untreated films was also made. The roughness and the root mean square (RMS) for pure PMMA films were continuously increased with increasing the exposure time for different gasses. SEM images observed degradation of the surface with granular spots due to the chain missioning and cross-linking effects. An efficient method of treatment for enhancing the surface roughness of pure-PMMA polymer is the using of argon plasma compared to O2, N2 plasma.

A new approach to the evaluation of ejection friction in micro injection molding

The ejection phase influences the quality and integrity of micro injection molded parts. The successful design of robust micro mold ejection systems requires studying the tribological interactions at the mold/polymer interface. At the micro-scale, the tooling topography can have a significant impact on the ejection friction. Here we propose a novel approach to the evaluation of ejection friction in micro injection molding. The two main contributors to the ejection force are the normal force due to shrinkage and the static friction coefficient. The former is addressed by developing a procedure for shrinkage characterization at the micro-scale. The latter is studied using experimental measurements of the ejection force in micro injection molding. Comparing the numerical and the experimental results allows identifying the friction coefficient as a function of polymer, process parameters, and mold surface roughness.

Single-Cell Tracking on Polymer Microarrays Reveals the Impact of Surface Chemistry on Pseudomonas aeruginosa Twitching Speed and Biofilm Development.

Bacterial biofilms exhibit up to 1000 times greater resistance to antibiotic or host immune clearance than planktonic cells. Pseudomonas aeruginosa produces retractable type IV pili (T4P) that facilitate twitching motility on surfaces. The deployment of pili is one of the first responses of bacteria to surface interactions and because of their ability to contribute to cell surface adhesion and biofilm formation, this has relevance to medical device-associated infections. While polymer chemistry is known to influence biofilm development, its impact on twitching motility is not understood. Here, we combine a polymer microarray format with time-lapse automated microscopy to simultaneously assess P. aeruginosa twitching motility on 30 different methacrylate/acrylate polymers over 60 min post inoculation using a high-throughput system. During this critical initial period where the decision to form a biofilm is thought to occur, similar numbers of bacterial cells accumulate on each polymer. Twitching motility is observed on all polymers irrespective of their chemistry and physical surface properties, in contrast to the differential biofilm formation noted after 24 h of incubation. However, on the microarray polymers, P. aeruginosa cells twitch at significantly different speeds, ranging from 5 to ∼13 nm/s, associated with crawling or walking and are distinguishable from the different cell surface tilt angles observed. Chemometric analysis using partial least-squares (PLS) regression identifies correlations between surface chemistry, as measured by time-of-flight secondary ion mass spectrometry (ToF-SIMS), and both biofilm formation and single-cell twitching speed. The relationships between surface chemistry and these two responses are different for each process. There is no correlation between polymer surface stiffness and roughness as determined by atomic force measurement (AFM), or water contact angle (WCA), and twitching speed or biofilm formation. This reinforces the dominant and distinct contributions of material surface chemistry to twitching speed and biofilm formation.

Understanding the effect of solvent additive in polymeric thin film: turning a bilayer into a bulk heterojunction-like photovoltaic device

Here we report the effect of an additive solvent, 1,8-diiodooctane (DIO), on the performance of a bilayer organic photovoltaic device in which the active layer comprises poly[2,7-(9,9-bis(2 ethylhexyl)-dibenzosilole)-alt-4,7-bis(thiophen-2-yl)benzo-2,1,3-thiadiazole] (PSiF-DBT) as the electron donor material and C60 as the electron acceptor material. We observed that when the donor layer was treated with 1% of DIO the power conversion efficiency (PCE) of the device increased by 138.4% in relation to the device with an untreated donor layer, and 21.3% in relation to the device containing a donor layer submitted to thermal annealing. The main effects that lead to this increase in PCE are the large interfacial area between donor and acceptor materials and the improved conductivity at low voltages. The increase in polymer surface roughness leads to a more effective PSiF-DBT/C60 interface for exciton dissociation. This effect, as well as the increase in the conductivity, raised the short circuit current density (JSC) to 13.89 mA cm−2 and the PCE to 4.84%. Our conclusions are supported by morphological analysis, chemical cross-sectional evaluations with advanced microscopy techniques, charge mobility measurements, as well as by theoretical simulations of the devices in which the changes on the donor/acceptor interfacial area were considered. The outcomes suggest that solvent additives could be an alternative treatment to replace the thermal annealing, which imposes further difficulties in performing lab-to-manufacturing upscaling.

Theoretical Determination of the Minimum Thickness of a Polymer Layer Providing Ensured Protection of a Shaft–Bearing Joint from Fretting Corrosion

Fretting corrosion in a shaft–bearing joint has been investigated. The effect of the elastic characteristics of the polymer material and surface roughness of the shaft and bearing on the magnitude of the minimum possible thickness of the polymer layer at which it would be assured of retaining strength characteristics has been theoretically studied. A design equation for this magnitude has been derived. The minimum thickness of the polymer layer in the shaft–bearing joint for particular conditions (surface roughness, elasticity modulus, and maximum load) has been determined.

Abrasive flow finishing for surface roughness improvement of aluminum propeller: A case study

The manufacturing of a precise complex component is concerned with the most critical phase of final finishing operation. Most of the traditional finishing process has limitations, while addressing challenges with finishing inaccessible, intricate, complex shape components need to be addressed with non-traditional finishing methods. Abrasive flow finishing machine (AFFM) one of the non-traditional finishing technique is well known for the polishing, deburring, radiusing and induce compressive residual stress. The current work investigates on surface roughness improvement through Abrasive flow finishing process of aluminum (6061-T6) propeller for a strategic application. The proper AFFM fixturing for the aluminum propeller component is designed and fabricated. Experimentation is conducted with abrasive flow finishing machine (AFFM-150D) using visco-elastic abrasive polymer media prepared through two roll mixer machine. An attempt is made to characterize the visco-elastic abrasive polymer media and surface roughness on the propeller blade surfaces at different stages of the AFFM process.

Oxyfluorination-Controlled Variations in the Wettability of Polymer Film Surfaces

The modification of polymer surfaces with fluorine–oxygen mixtures has been studied with wide variations in the process duration and percentage ratio between these gases in the mixture. The modification increases the hydrophilicity of the polymer surface, and, the higher the fraction of oxygen in the gas mixture and the longer the oxyfluorination time, the greater the increase in the hydrophilicity. The physicochemical properties of polymers, such as wettability, surface energy, and adhesion, may be regulated within rather wide ranges by varying oxyfluorination conditions. For example, in the case of polyolefins, the water contact angle changes from 78°‒87° for initial polymers to 49°‒60° for modified ones. For heterochain polymers, this range may be even wider and is for, e.g., poly(ethylene terephthalate) from 67° to 4°; i.e. almost complete water spreading over the polymer surface is achieved. The contribution of the polymer surface roughness to the observed values of the water contact angle has been determined before and after the chemical treatment. It has been shown that an increase in the wettability of the polymer surface as a result of oxyfluorination may be used to obtain polymer films capable of altering their wettability under subsequent tensile deformation.

Effect of cutting parameters on surface roughness in ultra-high precision turning of a contact lens polymer

This paper studies the effect of cutting parameters on surface generation in ultra-precision turning of a contact lens polymer. Contact lens manufacture wants high accuracy and high surface quality. Surface roughness is mostly used to measure the index quality of a turning process. It has been an important response because it has direct influence toward the part performance and the production cost. Hence, choosing optimal cutting parameters will not only improve the quality measure but also the productivity. This research work is therefore aimed at investigating the effect of cutting parameters (cutting speed, feed rate and depth of cut) on surface roughness of RGP ONSI-56 contact lens polymer with a monocrystalline diamond cutting tool. In this work, cutting speed (A) is found to be the most dominant factor having the highest degree of significance followed by the square of the cutting speed (A2) and the feed rate (B). However, interaction between cutting speed and feed rate (AB) has the lowest degree of significance on the surface roughness.

Tethered hydrophilic polymers layers on a polyamide surface

ABSTRACTModification of the hydrophilicity of a polyamide surface with tethered poly(acrylic acid), poly(vinylsulfonic acid), or poly(2‐hydroxyethyl methacrylate) was accomplished by atmospheric pressure plasma surface activation, followed by free radical graft polymerization with vinyl monomers. Surface activation was more effective with He relative to H2 plasma leading to thicker grafted polymer layers of higher surface density. The thickness and surface roughness of the tethered layers were up to ~9.7 nm and ~3.6 nm, respectively. Upon surface modification, the free energy of hydration decreased (25–51%) and the polar component of the surface energy increased (by a factor of 3.0–6.5); the above indicating increased hydrophilicity of the modified surface which also correlated with the tethered polymer layer thickness and surface roughness. The present study suggests that surface hydrophilicity tuning is feasible through the combination of surface chemistry, plasma surface treatment, and graft polymerization conditions. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46843.