Polymethymethacrylate Research Articles

A comparative in vitro analysis of various temporization materials with respect to pulp chamber temperature changes during polymerization.

(1) To compare the temperature rise in the pulp chamber with different resin materials used for making provisional fixed partial dentures in anterior and posterior region while using Polyvinylsiloxane impression materials as matrix. (2) To identify a superior provisionalization material based on the amount of heat dissipated suitable for anterior and posterior provisional fixed partial denture fabrication. Temporary crowns and bridges are integral to Fixed Prosthodontics. It has been observed that conventional fixed prosthesis temporisation materials release heat due to the exothermic polymerisation reaction. When such a provisional material is directly let to set on a vital tooth, the heat transfer causes irreversible changes in the pulp tissue depending of the degree of change. Hence, this study observes amount of heat generation in various materials during temporisation procedure, by simulating similar conditions. Two Models were fabricated, one simulating missing lateral incisor (Model A) and another simulating missing first molar (Model B). Intact maxillary central incisors and canine for Model A and intact mandibular Second Premolar and Second Molar were selected to act as abutments. These abutment teeth were fitted with the tip of a K-type Thermocouple inside their pulp chambers and these were connected to a digital thermometer. Five temporisation materials were chosen for fabrication of temporary crowns through Direct technique. (1) polymethy methacrylate (Self Cure acrylic), (2) bisacryl composite (Protemp 4), (3) visible light cure urethane dimethacrylate (Revotec LC), (4) barium glass and fumed silica infused methacrylate (Dentsply Integrity) and (5)nano-hybrid composite (VOCO Structur 3). Ten observations were made for each provisional material on each model. During each observation, temperature rise was recorded at 30s interval from the time of application, through the peak and till a decrease in temperature is observed. Polyvinyl siloxane was used as matrix for all except light cure resin, where polypropylene sheet was used. Anova test used for statistical. ANOVA test revealed that there was a significant difference in the temperature changes associated with the provisional restorative materials used. Among the five, polymethy methacrylate (self cure resin) showed the maximum rise in temperature, followed by bisacryl composite (Protemp 4), visible light cure urethane dimethacrylate (Revotec LC), barium glass and fumed silica infused methacrylate (Dentsply Integrity) and nano-hybrid composite (VOCO Structur 3). There was no comparable difference between Model A and B but an overall reduction of temperature rise was observed in model B. VOCO Structur 3 showed the least temperature rise in the pulp chamber, and overall temperature rise was less for model B which can be attributed to the residual dentin thickness.

Modification of polymethylmethacrylate under irradiation of the SEM electron beam

This paper is focused on the study of the modifications of polymethymethacrylate (PMMA) under irradiation of electron beams. PMMA is a well-known thermoplastic synthetic polymer, with unique features such as transparency, good tensile strength, and moldability. Its performance can be significantly modified through the realization of functionalized thin film coatings, ion irradiations, laser irradiations for different applications, such as flexible electronics, biomaterials, dielectric layers and sensors. The purpose of this paper is to describe the changes of the PMMA features as a function of the energy and fluence of electron beams. The morphology of the obtained structures is studied by electron scanning microscopy while the C/O atomic ratios are monitored by the energy dispersive X-ray spectroscopy.

Modification of polymethylmethacrylate under irradiation of the SEM electron beam

This paper is focused on the study of the modifications of polymethymethacrylate (PMMA) under the irradiation of electron beams. PMMA is a well-known thermoplastic synthetic polymer, with unique features such as transparency, good tensile strength, and moldability. Its performance can be significantly modified through the realization of functionalized thin film coatings, ion irradiations, laser irradiations for different applications, such as flexible electronics, biomaterials, dielectric layers and sensors. The purpose of this paper is to describe the changes of the PMMA features as a function of the energy and fluence of electron beams. The morphology of the obtained structures is studied by electron scanning microscopy while the C/ O atomic ratios are monitored by the energy dispersive X-ray spectroscopy.

Reactive Processing of Acrylic-Based Thermoplastic Composites: A Mini-Review

The demand for thermoplastic composites is continuously increasing because these materials offer many advantages over their thermoset counterparts, such as high toughness, long storage time, easy repairing and recycling, and ability to be thermoformed and heat-welded. However, the manufacturing of thermoplastic composite parts using liquid composite moulding techniques (e.g. resin transfer moulding, vacuum assisted resin transfer moulding … ) is often tricky in the case of melt processing where high temperature and pressure should be chosen to impregnate the fibre reinforcement because of the high melt viscosity of thermoplastics. These issues may be overcome by means of reactive processing where a fibrous preform is first impregnated by a low viscosity mono- or oligomeric precursor and the polymerization of the thermoplastic matrix then occurs in-situ. This article draws a state of the art on the manufacturing characteristics of continuous fibre reinforced acrylic-based reactive thermoplastics (e.g. polymethymethacrylate (PMMA) such as Elium®), which are becoming more and more popular compared to other fast curing thermosets and thermoplastics for in-situ polymerization. Techniques for the in-situ polymerization of methymethacrylate monomers, characterization and modelling of the rheological properties and polymerization kinetics, and some manufacturing related issues such as polymerization shrinkage are reviewed. Particular features of the use of reactive PMMA in different manufacturing techniques of continuous fibre reinforced composites and potential industrial applications are also introduced. Finally, some perspectives for the academic research and industrial development are proposed.

Innovative Methods in Monitoring and Analysis of Emission Production in Solid Fuel Heat Sources

In this paper, different and innovative ideas of monitoring and analysis of emissions produces by small heat sources are presented and described. This paper follows up research made in master’s thesis from 2022 where two wireless prototypes meant for analyzing emission production were designed, constructed and successfully tested. First prototype made from Polymethymethacrylate (PMMA) successfully analyzed parameters such as concentration of CO, CO2, VOC or dust particles PM in air of indoor temperature during various types of tests. Second prototype made from stainless steel was used to analyze flue gases directly connected to the chimney from a household using small stove and different kinds of fuel. Evaluation of these experiments in IoT platform named ThingSpeak showed significant increase of concentration of emissions produced during burning unsuitable fuel (such as wet grass) compared to more suitable fuel such as dry wood.

Validation of a Locally Designed Computed Tomography Dose Phantom: A Comparison Study with a Standard Acrylic Phantom in South-South, Nigeria

Purpose: The aim of this study was to determine the mean volume computed tomography dose index (CTDIvol) for the standard head and body phantoms and locally designed head and body phantoms respectively. Similarly, this study determined and compared the displayed mean CTDIvol and Dose Length Product (DLP) for the above phantoms from the CT monitor. In addition, the percentage deviations of both phantoms were compared with the recommended limits from the International Atomic Energy Agency (IAEA) and the American College of Radiologists (ACR). Materials and Methods: Dose measurements were made using a standard polymethymethacrylate (PMMA) phantom for head and body as well as a locally designed phantom with four CT scanners using thermoluminescence dosimeters (TLDs). The locally designed phantoms were made using a PMMA sheet, which was bent to give the desired cylindrical shape and was made like the standard phantoms. The constructed phantom was filled with water and the TLD chips were inserted into the center and peripheries of the phantoms to obtain the absorbed doses. Results: The CTDIvol for the standard head and body phantom for center A was 66.97 and 21.85mGy and for B was 23.39 and 6.29mGy respectively. Similarly, the CTDIvol for the constructed head and body phantom for center A was 63.91 and 19.84mGy and for B was 24.67 and 6.30mGy respectively. The uncertainty between the standard and constructed head phantoms for centers A and B was 4.6 and 5.5% respectively, while that of the standard and constructed body phantoms for centers A and B was 9.2 and 0.0% respectively. The maximum percent deviation from the console CTDIvol and DLP values with the four phantoms for centers A and B was within ±20%. The mean correction factors for the head and body were 0.998 and 1.05 respectively. Conclusion: The uncertainties obtained in this study were within the IAEA and ACR recommended value of ±20%. The constructed phantom proved useful for CT dose measurements.

FATAL CENTRAL PULMONARY CEMENT EMBOLISM AFTER KYPHOPLASTY

SESSION TITLE: Case Report Semifinalists 8 SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/21/2019 02:30 PM - 03:15 PM INTRODUCTION: A 61-year old male presented to the emergency department with progressive shortness of breath two days after a kyphoplasty of T11-L1 due to a T12 fracture. The immediate post-operative course was uneventful. No post-procedure imaging was ordered and the patient was discharged to a rehabilitation center the day after surgery. CASE PRESENTATION: Vital signs showed a heart rate of 108 beats per minute, blood pressure of 130/87 mmHg, and temperature of 101 degrees Fahrenheit. Physical exam demonstrated a patient in respiratory distress with decreased breath sounds and crackles bilaterally on auscultation. Arterial blood gas demonstrated severe hypoxemia. An abdominal CT incidentally confirmed large polymethymethacrylate (PMMA) bone cement embolisms in both main pulmonary arteries and in a vertebral vein anterior to T11. He soon became obtunded with rapidly progressive hemodynamic and respiratory failure, was intubated and transferred to the intensive care unit. Despite all resuscitation efforts, he went into refractory shock necessitating vasopressors. Due to the ongoing progression of cardiac and hypoxemic respiratory failure and scarcity of therapeutic options, the patient was transferred to a hospital with a cardiothoracic surgery team for possible extra corporeal membrane oxygenation (ECMO) or surgical pulmonary artery embolectomy. After a safe transfer, the patient went into cardiopulmonary arrest while being evaluated and expired before he could benefit from any procedure. DISCUSSION: Pulmonary cement embolisms (PCE) are a complication of percutaneous vertebroplasty (PV) and balloon kyphoplasty procedures. In both procedures PMMA is injected into the body of the vertebra, either directly (vertebroplasty) or within an inflated balloon (kyphoplasty). Cement can leak into the vertebral vein, continue to the inferior vena cava and reach the pulmonary arteries. Fatalities due to PCE remain extremely rare, relate to PV, and occur during the procedure (3,6) or a few days after (7,8). Our case is, to our knowledge, the first fatality occurring in a kyphoplasty patient. CONCLUSIONS: No standardized treatment exists for PCE but many interventions are possible to retrieve larger emboli before they can become life threatening, if they are identified immediately (1,2,4,5). Additional studies should be conducted to identify patients at risk and avoid this occurrence. In the meantime, it seems reasonable to infer from past cases and our personal experience that routine intra-operative identification of leakages with fluoroscopy and post-operative CXR may be helpful in rapid recognition and treatment of this patient population before they become symptomatic and irreversibly hemodynamically unstable. Reference #1: 1. Barbero, S, et al. “Percutaneous Vertebroplasty: the Follow-up.” Current Neurology and Neuroscience Reports., U.S. National Library of Medicine, Feb. 2008, www.ncbi.nlm.nih.gov/pubmed/18338131. Reference #2: 2. Baumann, A. et al. Cement Embolization into the Vena Cava and Pulmonal Arteries After Vertebroplasty: Interdisciplinary Management. European Journal of Vascular and Endovascular Surgery, Volume 31 , Issue 5 , 558 - 561 3. Chen, H L, et al. “A Lethal Pulmonary Embolism during Percutaneous Vertebroplasty.” Current Neurology and Neuroscience Reports., U.S. National Library of Medicine, Oct. 2002, www.ncbi.nlm.nih.gov/pubmed/12351294/. 4. François, K, et al. “Successful Management of a Large Pulmonary Cement Embolus after Percutaneous Vertebroplasty: a Case Report.” Current Neurology and Neuroscience Reports., U.S. National Library of Medicine, 15 Oct. 2003, www.ncbi.nlm.nih.gov/pubmed/14560098. Reference #3: 5. Li, Z, et al. “Cement Embolus Trapped in the Inferior Vena Cava Filter during Percutaneous Vertebroplasty.” Current Neurology and Neuroscience Reports., U.S. National Library of Medicine, 2013, www.ncbi.nlm.nih.gov/pubmed/23690712. 6. Monticelli, F, et al. “Fatal Pulmonary Cement Embolism Following Percutaneous Vertebroplasty (PVP).” Current Neurology and Neuroscience Reports., U.S. National Library of Medicine, 20 Apr. 2005, www.ncbi.nlm.nih.gov/pubmed/15734107/. 7. Stricker, K, et al. “Severe Hypercapnia Due to Pulmonary Embolism of Polymethylmethacrylate during Vertebroplasty.” Current Neurology and Neuroscience Reports., U.S. National Library of Medicine, Apr. 2004, www.ncbi.nlm.nih.gov/pubmed/15041623/. 8. Yoo, K Y, et al. “Acute Respiratory Distress Syndrome Associated with Pulmonary Cement Embolism Following Percutaneous Vertebroplasty with Polymethylmethacrylate.” Current Neurology and Neuroscience Reports., U.S. National Library of Medicine, 15 July 2004, www.ncbi.nlm.nih.gov/pubmed/15247590/. DISCLOSURES: No relevant relationships by Mariam Abboud, source=Web Response No relevant relationships by Brooke McDonald, source=Web Response

Effect of Graphene Surface Functional Groups on the Mechanical Property of PMMA Microcellular Composite Foams

The functional groups on graphene sheets surface affect their dispersion and interfacial adhesion in polymer matrix. We compared the mechanical property of polymethymethacrylate (PMMA) microcellular foams reinforced with graphene oxide (GO) and reduced graphene oxide (RGO) to investigate this influence of functional groups. RGO sheets were fabricated by solvent thermal reduction in DMF medium. UV-Vis, FT-IR and XPS analyses indicate the difference of oxygen-containing groups on GO and RGO sheets surface. The observation of SEM illustrates that the addition of a smaller number of GO or RGO sheets causes a fine cellular structure of PMMA foams with a higher cell density(about 1011 cells/cm3) and smaller cell sizes (about 1–2 µm) owing to their remarkable heterogeneous nucleation effect. Compared to GO reinforced foams, the RGO/PMMA foams own lower cell density and bigger cell size in their microstructure, and their compressive strength is lower even when the reinforcement contents are the same and the foam bulk density is higher. These results indicate that the oxygen-containing groups on GO sheets’ surface are beneficial to adhere CO2 to realize a larger nucleation rate, and their strong interaction with PMMA matrix improves the mechanical property of PMMA foams.

Liquid PMMA: A High Resolution Polymethylmethacrylate Negative Photoresist as Enabling Material for Direct Printing of Microfluidic Chips

Polymethymethacrylate (PMMA) is one of the most important thermoplasts and a commonly used material in microsystem fabrication, for example, microfluidics owning mainly to its optical transparency, biocompatibility, low autofluorescence, and low cost. However, being a thermoplastic material PMMA is typically structured using industrial replication techniques making PMMA unsuitable for rapid prototyping. The fact that neither material nor processing technique can be directly transferred from laboratory to industrial state makes the research‐to‐business conversion often extremely difficult in microfluidics since material properties have a major impact on the final system behavior. This paper presents “Liquid PMMA,” a fast curing viscous PMMA prepolymer which can be used as a negative photoresist and directly structured using ultraviolet or visible light with tens of micron resolution and smooth surfaces. Using this technique microfluidic chips in PMMA can be fabricated within minutes. The cured Liquid PMMA parts show the same high optical transparency, low autofluorescence, and surface properties like commercial PMMA. In this way, microfluidic chips can be rapidly developed and optimized on the laboratory scale in the same material which is later on used on the industrial scale.

Extraction of 22 equine cheek teeth with displaced sagittal fractures using polymethylmethacrylate stabilisation (2011–2016)

SummaryDisplaced sagittal cheek tooth fractures are a cause of oral pain, quidding and apical infection. Intraoral extraction is the preferred technique to remove affected teeth, but can be difficult due to displaced and friable fracture fragments. Stabilising fracture fragments via filling of the fracture space with polymethymethacrylate (PMMA) prior to removal may be a useful method to facilitate intraoral extraction. Case details were examined retrospectively. A total of 22 cheek teeth required extraction in 20 horses because of displaced sagittal fractures. Clinical diagnoses were made using oral examination, oral endoscopy, skull radiography and computed tomography. All procedures were performed in standing, sedated horses in stocks. Fracture spaces were cleaned and packed with PMMA and teeth removed using a routine intraoral extraction technique. Digital photographs of extracted teeth were taken and tooth measurements calibrated using digital image software. Intraoperative difficulties, as well as post‐operative complications were recorded. A total of 21 maxillary and one mandibular cheek teeth were extracted. All maxillary teeth had advanced infundibular caries. Intraoral extraction was successful in 16 cases; six were unsuccessful and required repulsion due to tooth fragmentation or abnormal dental anatomy. In 11 cases, maxillary or conchofrontal sinus trephination was performed to either treat sinusitis, repulse the tooth, or both. Two horses developed short‐term complications following local anaesthesia of the maxillary nerve. The mean ratio of fracture depth to tooth length was 0.59 and mean ratio of fracture width to tooth width 0.53. The limitations of the study are its small sample size, retrospective nature and lack of control group to compare extraction success in PMMA and non‐PMMA groups. It was concluded that using PMMA to stabilise displaced sagittal fractures in equine cheek teeth is a simple, effective method of facilitating intraoral extraction and may reduce the need for more invasive procedures.

Dynamic mixed-mode fracture behaviors of PMMA and polycarbonate

Mixed-mode dynamic crack initiation and growth in polymethymethacrylate (PMMA) and polycarbonate (PC) are studied experimentally. A simple specimen geometry in conjunction with a dynamic loading configuration to generate different mode-mixities at crack initiation is demonstrated. A Hopkinson pressure bar is used to rapidly load free-standing edge cracked samples in a reverse impact configuration. By eccentrically loading the specimen relative to the crack line, various mode-mixities at crack initiation are achieved by increasing the initial crack length while keeping all other experimental parameters the same. A relatively new full-field optical technique, Digital Gradient Sensing (DGS), along with high-speed photography is used to perform full-field measurements. DGS measures instantaneous angular deflections of light rays representing two orthogonal stress gradients under plane stress conditions. The mode-I and -II stress intensity factor histories are evaluated via over-deterministic least-squares analysis of optically measured data. By quantifying the critical stress intensity factors evaluated at crack initiation, dynamic fracture envelopes are developed for both the polymers. The results are studied comparatively and relative to the brittle fracture criteria. From measured stress intensity factors and crack speeds in the post-initiation regime, energy release rate vs. velocity plots for different mixed-mode configurations are produced for both the polymers.

The properties of inducible membranes in animals and humans

Membranes form around spacers used in large bone defects. We studied the effect of the spacer material on the ability of the membrane to promote osteogenesis in an animal model and the gene expression patterns of membranes obtained from humans. Critical-sized osseous defects were created in the ulnae of 12 rabbits. Stainless steel (SS) or polymethymethacrylate (PMMA) spacers were inserted into the defects, and the animals healed for four or eight weeks. After sacrifice, samples of the membrane were grown in cell culture. Human membrane samples were collected for gene expression analyses. Cultures of rabbit membranes with bone marrow cells showed significantly greater alkaline phosphatase activity (PMMA) and mineral deposition (SS) than bone marrow cells alone. All membranes had elevated expression of osteoblast-related genes. Inducible membranes around orthopaedic implants likely contain active cells of the OB lineage and the spacer material may influence the healing properties of the membrane.

The properties of inducible membranes in animals and humans

Membranes form around spacers used in large bone defects. We studied the effect of the spacer material on the ability of the membrane to promote osteogenesis in an animal model and the gene expression patterns of membranes obtained from humans. Critical-sized osseous defects were created in the ulnae of 12 rabbits. Stainless steel (SS) or polymethymethacrylate (PMMA) spacers were inserted into the defects, and the animals healed for four or eight weeks. After sacrifice, samples of the membrane were grown in cell culture. Human membrane samples were collected for gene expression analyses. Cultures of rabbit membranes with bone marrow cells showed significantly greater alkaline phosphatase activity (PMMA) and mineral deposition (SS) than bone marrow cells alone. All membranes had elevated expression of osteoblast-related genes. Inducible membranes around orthopaedic implants likely contain active cells of the OB lineage and the spacer material may influence the healing properties of the membrane.

Thermal Degradation of Poly Methy Methacrylate (PMMA) Doped with Optically Active Molecules/Applications in Photovoltaic Conversion

Thermal Degradation of Poly Methy Methacrylate (PMMA) Doped with Optically Active Molecules/Applications in Photovoltaic Conversion

Preparation of PMMA/graphene oxide microcellular foams using supercritical carbon dioxide

Microcellular foams have a widely applications in many industries due to their superior properties. In this paper, the polymethymethacrylate (PMMA)/graphene oxide (GO) microcellular foams were prepared by supercritical carbon dioxide as a friendly foaming agent. The effect of graphene oxide amount on cellular structure and mechanical strength of foams had been investigated. Microstructure characterization bases on scanning electron microscopy (SEM). The cell size and cell density were calculated via image analysis. It was found that the average foam cell size was decreased from 20.1 μm to 2.2 μm and the cell density was increased from 2.8×108 to 3.3×1010 when 1.5wt.% GO sheets were added into PMMA matrix. In addition, the compression strength of polymeric foams was increased from 13 MPa to 39 MPa.

Effects of the polymeric niche on neural stem cell characteristics during primary culturing

The polymeric niche encountered by cells during primary culturing can affect cell fate. However, most cell types are primarily propagated on polystyrene (PS). A cell type specific screening for optimal primary culture polymers particularly for regenerative approaches seems inevitable. The effect of physical and chemical properties of treated (corona, oxygen/nitrogen plasma) and untreated cyclic olefin polymer (COP), polymethymethacrylate (PMMA), PP, PLA, PS, PC on neuronal stem cell characteristics was analyzed. Our comprehensive approach revealed plasma treated COP and PMMA as optimal polymers for primary neuronal stem cell culturing and propagation. An increase in the number of NT2/D1 cells with pronounced adhesion, metabolic activities and augmented expression of neural precursor markers was associated to the plasma treatment of surfaces of COP and PMMA with nitrogen or oxygen, respectively. A shift towards large cell sizes at stable surface area/volume ratios that might promote the observed increase in metabolic activities and distinct modulations in F-actin arrangements seem to be primarily mediated by the plasma treatment of surfaces. These results indicate that the polymeric niche has a distinct impact on various cell characteristics. The selection of distinct polymers and the controlled design of an optimized polymer microenvironment might thereby be an effective tool to promote essential cell characteristics for subsequent approaches.

Study on the Erosion Wear Behaviors of the PMMA Plates Impacted by Air Flow Containing Sands

The polymethymethacrylate (PMMA) plate was adopted as the test samples. The effects of impact angle, impact velocity, sand size on the erosion wear of the PMMA plates were experimentally investigated. The erosion mechanisms were also analyzed. The results showed that, the erosion volume increased nonlinearly with the increase of impact velocity, the inflection point appeared at around 13 m/s, and then the erosion volume increased rapidly. The erosion volume decreased nonlinearly as the impact angle increased. In our experiments, under the impact angle less than 60°, the smaller sand size could result in higher erosion wear. However, at 90°, the erosion volume by larger sands produced higher erosion. In fact, the erosion mechanism depends on the impact angle, at small impact angles, the main erosion mechanism is micro-cutting, and the erosion mechanism will mainly be impacting fatigue at large impact angles. At the medium impact angles, the erosion mechanism is the combination of the micro-cutting and impacting.

Sensitivity analysis of periprosthetic healing to cell migration, growth factor and post-operative gap using a mechanobiological model

A theoretical rationale, which could help in the investigation of mechanobiological factors affecting periprosthetic tissue healing, is still an open problem. We used a parametric sensitivity analysis to extend a theoretical model based on reactive transport and computational cell biology. The numerical experimentation involved the drill hole, the haptotactic and chemotactic migrations, and the initial concentration of an anabolic growth factor. Output measure was the mineral fraction in tissue surrounding a polymethymethacrylate (PMMA) canine implant (stable loaded implant, non-critical gap). Increasing growth factor concentration increased structural matrix synthesis. A cell adhesion gradient resulted in heterogeneous bone distribution and a growth factor gradient resulted in homogeneous bone distribution in the gap. This could explain the radial variation of bone density from the implant surface to the drill hole, indicating less secure fixation. This study helps to understand the relative importance of various host and clinical factors influencing bone distribution and resulting implant fixation.

Photoinduced effects in γ-glycine nanocrystallites embedded in polymer matrices

We have established a principal role of the polarity of polymer matrices on the piezooptical dispersion of the γ-glycine nanocrystallites embedded into the polymethymethacrylate (PMMA) and polycarbonate (PC) matrices. We found that the optical treatment by bicolor two laser beams at 1064 nm and 532 nm which are originating from the same 10 ns Nd:YAG laser, causes occurrence of the piezooptical effects. The optimal content of the γ-glycine nanocrystallites with respect to the magnitude of piezooptical coefficients was within the range of size 50–80 nm, corresponding to the 6.5 wt.%. We studied relaxation and spectral dependence of the corresponding coefficients of the piezooptic tensor.

Self-organization of ZnO wrinkles oriented by patterned PMMA templates

In this study, well-ordered ZnO wrinkles were fabricated by sol–gel derived ZnO films via heat treatment at 400 °C for 2 h with the assistance of polymethymethacrylate (PMMA) templates. PMMA templates with various patterns were employed to investigate the effects of template geometries on arrangements of the formed ZnO wrinkles. The influence of thickness on the transformation of the entire resulting structures of the spin-coated ZnO sol–gel films is discussed. With 2-dimensional arrangement of PMMA patterns, more than two orientations of wrinkled ZnO can be induced in one template. By controlling the arrangement of PMMA patterns and thickness of ZnO sol–gel films, specific circular, hexagonal, triangular and triangular-star complex structures were produced due to the constrained shrinkage force of the ZnO films applied toward the PMMA side walls during drying. By this technique, we can obtain 3-dimensional ZnO structures that conventional photolithography and nano-imprinting lithography are hard to achieve in few process steps.