Elastomeric Poly Research Articles

Nitro-Oleic Acid (NO2-OA) Release Enhances Regional Angiogenesis in a Rat Abdominal Wall Defect Model.

Ventral hernia is often addressed surgically by the placement of prosthetic materials, either synthetic or from allogeneic and xenogeneic biologic sources. Despite advances in surgical approaches and device design, a number of postsurgical limitations remain, including hernia recurrence, mesh encapsulation, and reduced vascularity of the implanted volume. The in situ controlled release of angiogenic factors from a scaffold facilitating abdominal wall repair might address some of these issues associated with suboptimal tissue reconstruction. Furthermore, a biocomposite material that combines the favorable mechanical properties achievable with synthetic materials and the bioactivity associated with xenogeneic tissue sources would be desirable. In this report, an abdominal wall repair scaffold has been designed based on a microfibrous, elastomeric poly(ester carbonate)urethane urea matrix integrated with a hydrogel derived from decellularized porcine dermis (extracellular matrix [ECM] gel) and poly(lactic-co-glycolic acid) (PLGA) microspheres loaded with nitro-oleic acid (NO2-OA). NO2-OA is an electrophilic fatty acid nitro-alkene derivative that, under hypoxic conditions, induces angiogenesis. This scaffold was utilized to repair a rat abdominal wall partial thickness defect, hypothesizing that the nitro-fatty acid release would facilitate increased angiogenesis at the 8-week endpoint. The quantification of neovascularization was conducted by novel methodologies to assess vessel morphology and spatial distribution. The repaired abdominal wall defects were evaluated by histopathologic methods, including quantification of the foreign body response and cellular ingrowth. The results showed that NO2-OA release was associated with significantly improved regional angiogenesis. The combined biohybrid scaffold and NO2-OA-controlled release strategy also reduced scaffold encapsulation, increased wall thickness, and enhanced cellular infiltration. More broadly, the three components of the composite scaffold design (ECM gel, polymeric fibers, and PLGA microparticles) enable the tuning of performance characteristics, including scaffold bioactivity, degradation, mechanics, and drug release profile, all decisive factors to better address current limitations in abdominal wall repair or other soft tissue augmentation procedures.

Improvement of physical properties of poly(glycerol sebacate) by copolymerization with polyhydroxybutyrate-diols

The characterizations and physical properties of elastomeric poly(glycerol sebacate) (PGS) copolymerized with different amounts of polyhydroxybutyrate diol (PHB-diol) were analyzed with 1H-NMR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), mechanical test, biodegradation test, and cytotoxicity analysis. The chemical composition of the PHB-diol prepared and the copolymerization reaction of the PHB-diol in the PGS were confirmed by 1H-NMR. From 1H-NMR analysis, the PHB-diol prepared had the molecular weight about 989.6 g/mol and a faster crystallization rate than the PHB according to the DSC measurement. The tensile/compressive strengths of PGS-co-(PHB-diol) increased while the crosslinking densities decreased with the amount of PHB-diol copolymerized. The PGS-co-(PHB-diol) had a slower biodegradation rate but a worse thermal stability than the PGS. Additionally, the biodegradable PGS-co-(PHB-diol) elastomers prepared exhibited no cytotoxicity and could replace PGS used in bio-fields.

The Functional Response of Mesenchymal Stem Cells to Electron-Beam Patterned Elastomeric Surfaces Presenting Micrometer to Nanoscale Heterogeneous Rigidity.

Cells directly probe and respond to the physicomechanical properties of their extracellular environment, a dynamic process which has been shown to play a key role in regulating both cellular adhesive processes and differential cellular function. Recent studies indicate that stem cells show lineage-specific differentiation when cultured on substrates approximating the stiffness profiles of specific tissues. Although tissues are associated with a range of Young's modulus values for bulk rigidity, at the subcellular level, tissues are comprised of heterogeneous distributions of rigidity. Lithographic processes have been widely explored in cell biology for the generation of analytical substrates to probe cellular physicomechanical responses. In this work, it is shown for the first time that that direct-write e-beam exposure can significantly alter the rigidity of elastomeric poly(dimethylsiloxane) substrates and a new class of 2D elastomeric substrates with controlled patterned rigidity ranging from the micrometer to the nanoscale is described. The mechanoresponse of human mesenchymal stem cells to e-beam patterned substrates was subsequently probed in vitro and significant modulation of focal adhesion formation and osteochondral lineage commitment was observed as a function of both feature diameter and rigidity, establishing the groundwork for a new generation of biomimetic material interfaces.

Dopamine-Incorporated Dual Bioactive Electroactive Shape Memory Polyurethane Elastomers with Physiological Shape Recovery Temperature, High Stretchability, and Enhanced C2C12 Myogenic Differentiation.

Soft tissue engineering needs elastic biomaterials not only mimicking the elasticity of soft tissue but also possessing multiple bioactivity to promote cell adhesion, proliferation, and differentiation, which still remain ongoing challenges. Herein, we synthesized a series of dopamine-incorporated dual bioactive electroactive shape memory polyurethane elastomers by combining the properties of elastomeric poly(citric acid-co-polycaprolactone) (CA-PCL) polyurethane elastomer, bioactive dopamine (DA), and electroactive aniline hexamer (AH). The chemical structures, electroactivity, conductivity, thermal properties, hydrophilicity and hydration ability, mechanical properties, and degradability of the polyurethane elastomers were systematically characterized. The elastomers showed excellent shape fixity ratio and shape recovery ability under physiological conditions. The elastomers' elongation and stress were tailored by the AH content, whereas the hydrophilicity and hydration ability of the elastomers were adjusted by the content of DA and AH, as well as the doping state of AH. The viability and proliferation results of C2C12 cells seeded on the elastomers showed their excellent cytocompatibility. Additionally, by analyzing the protein and gene level, the promotion effect on myogenic differentiation of C2C12 cells by these elastomers compared to that by control groups (PCL80 000, CA-PCL elastomer, and CA-PCL elastomer with the DA segment) was demonstrated. Furthermore, the results from subcutaneous implantation confirmed the elastomers' mild host response in vivo. These results represent that these dopamine-incorporated dual bioactive electroactive shape memory polyurethane elastomers are promising candidates for soft tissue regeneration that is sensitive to electrical signals.

Assessment of aliphatic poly(ester-carbonate-urea-urethane)s potential as materials for biomedical application

Selected mechanical and biological properties of biodegradable elastomeric poly(ester-carbonate-urea-urethane)s (PECUUs) point towards their potential to be applied as scaffolds in tissue engineering. Here we explore their medical applicability taking into account their hemocompatibility and cytotoxicity. The influence of the ester monomer (derivatives of adipic and succinic acids), as well as diisocyanate type (IPDI and HDI) on the investigated PECUUs properties is presented. The presence of aliphatic diisocyanates, cyclic IPDI or linear HDI, governs the adhesion of Candida cells to these polymers offering the possibility to control the biofilm formation on their surface. In comparison to the linear form, cyclic diisocyanates with pentamethylene succinate or adipate fragments had two to three times lower biofilm mass formation on their surface. Reduced hemoglobin release from red blood cells observed during incubation of tested polymers with human erythrocytes suspension indicates their potential biocompatibility with human tissues. PECUUs were also able to support the growth of human keratinocytes HaCaT on their surface when coated with collagen. In effect, IPDI derivatives might possess a high potential for use in biomedical applications.

Tailoring the wettability and mechanical properties of electrospun poly(l-lactic acid)-poly(glycerol sebacate) core-shell membranes for biomedical applications

Tissue and biomedical engineering fields are in constant mutation and in searching for innovative processing techniques capable to tailor the material properties. In this work, poly(l-lactic acid) (PLLA) and elastomeric poly(glycerol sebacate) (PGS) were dissolved in the same solvents and electrospun together, in a single needle system. A core-shell structure where the hydrophilic PGS was placed onto the surface of the hydrophobic PLLA fibre was obtained for elastomeric concentrations up to 25wt%. It was found that the PLLA:PGS blends are immiscible and the blends present the melting temperatures of the individual polymers. Moreover, their surface properties were deeply influenced by the presence of the PGS, and a superhydrophilic membrane was obtained, after PGS curing at 120°C for 48h. When the concentration of PGS is up to 25wt%, the blend’s Young modulus decreases from ∼35.9±7.1 to 7.5±1.4MPa and a twofold improvement in the sample stretchability was observed, compared with the pristine PLLA electrospun samples. Finally, in vitro hypothalamus A59 nerve cell culture shows that the core-shell electrospun samples enhanced cell adhesion and proliferation, suggesting that these developed materials have great potentials for nerve regeneration and biomedical engineering applications.

Assessment of an engineered endothelium via single-photon emission computed tomography.

The clinical translation of cell-based therapeutics often requires highly sensitive, non-invasive imaging tools to assess cell function and distribution in vivo. The objective of this research was to determine whether human Sodium-Iodide Symporter (hNIS) ectopic expression in endothelial cells (ECs) in combination with single-photon emission computed tomography (SPECT) is a feasible approach to non-invasively monitor the presence and viability of an engineered endothelium on expanded polytetrafluoroethylene (ePTFE). Human umbilical vein endothelial cells (HUVECs) were transduced with pLL3.7-hNIS via lentivirus with multiplicity of infection (MOI) of 0, 2, 5, and 10 (n = 4). Ectopic expression of hNIS in HUVECs via optimized lentiviral transduction (MOI 5) enabled cell uptake of a radioisotope that can be detected by SPECT without affecting endothelial cell viability, oxidative stress, or antithrombogenic functions. The viability and distribution of an engineered endothelium grown on ePTFE coated with the biodegradable elastomer poly(1, 8 octamethylene citrate) (POC) and exposed to fluid flow was successfully monitored non-invasively by SPECT. We report the feasibility of a non-invasive, highly sensitive and functional assessment of an engineered endothelium on ePTFE using a combination of SPECT and X-ray computed tomography (SPECT/CT) imaging and hNIS ectopic expression in ECs. This technology potentially allows for the non-invasive assessment of transplanted living cells in vascular conduits. Biotechnol. Bioeng. 2017;114: 2371-2377. © 2017 Wiley Periodicals, Inc.

Microwave-assisted facile fabrication of porous poly (glycerol sebacate) scaffolds

The biodegradable elastomeric polyester poly(glycerol sebacate) (PGS) was developed for soft-tissue engineering. It has been used in various research applications such as wound healing, cartilage tissue engineering, and vascular grafting due to its biocompatibility and elastomeric properties. However conventional PGS manufacture is generally limited by the laborious reaction conditions needed for curing which requires elevated reaction temperatures, high vacuum and multi-day reaction times. In this study, we developed a microwave irradiation methodology to fabricate PGS scaffolds under milder conditions with curing times that are 8 times faster than conventional methods. In particular, we determined microwave reaction temperatures and times for maximum crosslinking of PGS elastomers, demonstrating that PGS is fully crosslinked using gradual heating up to 160 °C for 3 h. Porosity and mechanical properties of these microwave-cured PGS elastomers were shown to be similar to PGS elastomers fabricated by the conventional polycondensation method (150 °C under 30 Torr for 24 h). To move one step closer to clinical application, we also examined the biocompatibility of microwave-cured PGS using in vitro cell viability assays with primary baboon arterial smooth muscle cells (SMCs). These combined results show microwave curing of PGS is a viable alternative to conventional curing.

Microbial-based synthesis of highly elastomeric biodegradable poly(3-hydroxybutyrate-co-4-hydroxybutyrate) thermoplastic

This study reports the production of P(3HB-co-4HB) [Poly(3-hydroxybutyrate-co-4-hydroxybutyrate)] in possession of high molecular weight and elastomeric properties by Cupriavidus sp. USMAA1020 in single-stage mixed-substrate cultivation system. 1,4-butanediol and 1,6-hexanediol are found to be efficient substrate mixture that has resulted in high copolymer yield, occupying a maximum of 70wt% of the total biomass and producing higher 4HB monomer composition ranging from 31mol% to 41mol%. In substrate mixtures involving 1,6-hexanediol, cleavage of the 6-hydroxyhexanoyl-CoA produces Acetyl-CoA and 4-hydroxybutyryl-CoA. Acetyl-CoA is instrumental in initiating the cell growth in the single-stage fermentation system, preventing 4-hydroxybutyryl-CoA from being utilized via β-oxidation and retained the 4HB monomer at higher ratios. Macroscopic kinetic models of the bioprocesses have revealed that the P(3HB-co-4HB) formation appears to be in the nature of mixed-growth associated with higher formation rate during exponential growth phase; evidenced by higher growth associated constants, α, from 0.0690g/g to 0.4615g/g compared to non-growth associated constants, β, from 0.0092g/g/h to 0.0459g/g/h. The P(3HB-co-31mol% 4HB) produced from the substrate mixture exhibited high weight-average molecular weight, Mw of 927kDa approaching a million Dalton, and possessed elongation at break of 1637% upon cultivation at 0.56wt% C. This is the first report on such properties for the P(3HB-co-4HB) copolymer. The copolymer is highly resistant to polymer deformation after being stretched.

Fluorescent Poly(glycerol-co-sebacate) Acrylate Nanoparticles for Stem Cell Labeling and Longitudinal Tracking.

The stable presence of fluorophores within the biocompatible and biodegradable elastomer poly(glycerol-co-sebacate) acrylate (PGSA) is critical for monitoring the transplantation, performance, and degradation of the polymers in vivo. However, current methods such as physically entrapping the fluorophores in the polymer matrix or providing a fluorescent coating suffer from rapid leakage of fluorophores. Covalent conjugation of fluorophores with the polymers and the subsequent core-cross-linking are proposed here to address this challenge. Taking rhodamine as the model dye and PGSA nanoparticles (NPs) as the model platform, we successfully showed that the synthesized rhodamine-conjugated PGSA (PGSAR) NPs only released less than 30% rhodamine at day 28, whereas complete release of dye occurred for rhodamine-encapsulated PGSA (PGSA-p-R) NPs at day 7 and 57.49% rhodamine was released out for the un-cross-linked PGSAR NPs at day 28. More excitingly, PGSAR NPs showed a strong quantum yield enhancement (26.24-fold) of the fluorophores, which was due to the hydrophobic environment within PGSAR NPs and the restricted rotation of (6-diethylamino-3H-xanthen-3-ylidene) diethyl group in rhodamine after the conjugation and core-cross-linking. The stable presence of dye in the NPs and enhanced fluorescence allowed a longitudinal tracking of stem cells both in vitro and in vivo for at least 28 days.

Highly elastomeric poly(3-hydroxyoctanoate) based natural polymer composite for enhanced keratinocyte regeneration

ABSTRACTA novel nanocomposite material combining the biocompatible, elastomeric, natural, biodegradable homopolymer poly(3-hydroxyoctanoate) (P(3HO)) with hemostatic and antibacterial bioactive glass nanoparticles (n-BG) was developed as a matrix for skin related applications. P(3HO) is a unique member of the family of natural polyhydroxyalkanoate biopolymers. The P(3HO)/n-BG composite films were fabricated using the solvent casting method. Microstructural studies revealed n-BG particles both embedded in the matrix and deposited on the surface, which introduced nanotopography and increased its hydrophilicity. The composite exhibited an increase in the Young’s modulus when compared to the control, yet maintained flexible elastomeric properties. These changes in the surface topography and chemistry of the composite system led to an increase of protein adsorption and cytocompatibility for the seeded human keratinocyte cell line. The results from this study demonstrated that the fabricated P(3HO)/n-BG composite system is a promising novel matrix material with potential applications in skin tissue engineering and wound healing.

Lipid-induced degradation in biocompatible poly(Styrene-Isobutylene-Styrene) (SIBS) thermoplastic elastomer

The thermoplastic elastomer Poly(Styrene-block-Isobutylene-block-Styrene) (SIBS) is highly biocompatible, which has led to its use in several commercially-available implants. However, lipid-induced degradation has been previously identified as a primary cause of failure in long-term SIBS implants subject to mechanical loading. Thus, understanding the mechanisms and extent of lipid-induced damage and the role of styrene-isobutylene ratio and molecular weight is critical to improving longevity of SIBS-based implants in order to fully exploit the biocompatibility advantages. Samples of four different SIBS formulations were fabricated via compression molding, immersed to lipid saturation contents from 5 to 80% by weight, and tested in uniaxial tension, stress relaxation, and dynamic creep modes. Degradation mechanisms were investigated via infrared spectroscopy, chromatography, and microscopy. No evidence of lipid-induced chemical interactions or chain scissoring was observed. However, a decrease in tensile strength, loss of dynamic creep performance and faster relaxation with increasing lipid content is attributed to strong internal straining. The magnitude of these losses is inversely proportional to both molecular weight and styrene content, suggesting that selection of these variables during the design phase should be based not only on the mechanical requirements of the application, but the expected degree of lipid exposure.

Preparation and Performance of Silica/Epoxy Group-Functionalized Biobased Elastomer Nanocomposite

Epoxy group-functionalized biobased elastomer poly(dibutyl itaconate-ter-isoprene-ter-glycidyl methacrylate) (PDBIIG) was synthesized via redox emulsion polymerization using glycidyl methacrylate (GMA) as the epoxy group-included monomer. The silica/PDBIIG nanocomposite was prepared without adding silane coupling agents. The ring-opening reaction, which occurred between the hydroxyl groups on the silica surfaces and the epoxy groups of the PDBIIG chains during mixing and vulcanization, was confirmed via bound rubber tests and Fourier transform infrared spectroscopy. This reaction was facilitated through heat treatment at 150 °C effectively. The introduction of covalent bonds significantly improved the interfacial interaction and dispersion of silica, which was indicated by transmission electron microscopy and rubber process analyzer (RPA) results. With the same silica loading and compounding procedure, the inclusion of 3.7 wt % GMA increased the modulus at 100% strain by 150.0% and the modulus at 300% str...

Crystalline and Elastomeric Poly(monothiocarbonate)s Prepared from Copolymerization of COS and Achiral Epoxide

The semicrystalline poly(monothiocarbonate)s were prepared by the copolymerization of carbonyl sulfide (COS) and ethylene oxide, an achiral epoxide, using a bifunctional chromium(III) complex as catalyst. The resultant copolymer, possessing perfectly alternating structure, high molecular weight, and narrow polydispersity, has a melting temperature of 128.2 °C, with a melting enthalpy up to 75.44 J/g. Moreover, an ABA triblock copolymer containing the “hard” semicrystalline poly(ethylene monothiocarbonate) (A) and the “soft” amorphous poly(propylene monothiocarbonate) (B) is synthesized by stepwise addition of epoxides. The tensile testing demonstrates the triblock copolymer may have the potential as a thermoplastic elastomer.

Conductive Poly(epichlorhydrin)–Polyaniline Dodecylbenzenesulfonate [PECH-PAni.DBSA] Rubber Blends Prepared in Solution

Blends of poly(epichlorhydrin) elastomer [PECH] and polyaniline dodecylbenzenesulfonate [PAni.DBSA], with electrical conductivities up to 6.4×10−7 S cm−1, have been prepared by solution mixing and casting. The solubility parameters were calculated and the most suitable solvent (tetrahydrofuran) was selected for mutual solubility between PAni.DBSA and the compatible elastomer poly(epichlorhydrin) [PECH]. Fourier-transform infrared (FT-IR) spectra of PECH-PAni.DBSA blends contained features of the spectra of the pure materials, but with significant peak shifts due to changing intermolecular interactions between the polymers. Thermal decomposition steps of the conductive blends were investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The thermal stabilities of the blends were dependent on the ratio of PAni. DBSA to PECH. The electrical conductivities of blends with proportions of 1 to 50 wt% PAni.DBSA were measured by 2-probe and 4-probe techniques. The electrical conductivity increased with the proportion of PAni.DBSA, showing two percolation threshold stages, which were explained by a change in the conformation of the polymeric chains leading to an increase in the conductivity. The effects of composition on the glass transition in the blends were determined using thermomechanical analysis (TMA).

Sequel of MgO nanoparticles in PLACL nanofibers for anti-cancer therapy in synergy with curcumin/β-cyclodextrin

Pharmaceutical industries spend more money in developing new and efficient methods for delivering successful drugs for anticancer therapy. Electrospun nanofibers and nanoparticles loaded with drugs have versatile biomedical applications ranging from wound healing to anticancer therapy. We aimed to attempt for fabricating elastomeric poly (l-lactic acid-co-ε-caprolactone) (PLACL) with Aloe Vera (AV), magnesium oxide (MgO) nanoparticles, curcumin (CUR) and β-cyclodextrin (β-CD) composite nanofibers to control the growth of MCF-7 cells for breast cancer therapy. The study focused on the interaction of MgO nanoparticle with CUR and β-CD inhibiting the proliferation of Michigan Cancer Foundation-7 (MCF-7) breast cancer cells. FESEM micrographs of fabricated electrospun PLACL, PLACL/AV, PLACL/AV/MgO, PLACL/AV/MgO/CUR and PLACL/AV/MgO/β-CD nanofibrous scaffolds achieved bead free, random and uniform nanofibers with fiber diameter in the range of 786±286, 507±171, 334±95, 360±94 and 326±80nm respectively. Proliferation of MCF-7 cells was decreased by 65.92% in PLACL/AV/MgO/CUR with respect to PLACL/AV/MgO nanofibrous scaffolds on day 9. The obtained results proved that 1% CUR interacting with MgO nanoparticles showed higher inhibition of MCF-7 cells among all other nanofibrous scaffolds thus serving as a promising biocomposite material system for the breast cancer therapy.

Skeletal muscle derived stem cells microintegrated into a biodegradable elastomer for reconstruction of the abdominal wall.

A variety of techniques have been applied to generate tissue engineered constructs, where cells are combined with degradable scaffolds followed by a period of invitro culture or direct implantation. In the current study, a cellularized scaffold was generated by concurrent deposition of electrospun biodegradable elastomer (poly(ester urethane)urea, PEUU) and electrosprayed culture medium+skeletal muscle-derived stem cells (MDSCs) or electrosprayed culture medium alone as a control. MDSCs were obtained from green fluorescent protein (GFP) transgenic rats. The created scaffolds were implanted into allogenic strain-matched rats to replace a full thickness abdominal wall defect. Both control and MDSC-integrated scaffolds showed extensive cellular infiltration at 4 and 8wk. The number of blood vessels was higher, the area of residual scaffold was lower, number of multinucleated giant cells was lower and area of connective tissue was lower in MDSC-integrated scaffolds (p<0.05). GFP+cells co-stained positive for VEGF. Bi-axial mechanical properties of the MDSC-microintegrated constructs better approximated the anisotropic behavior of the native abdominal wall. GFP+cells were observed throughout the scaffold at ∼5% of the cell population at 4 and 8wk. RNA expression at 4wk showed higher expression of early myogenic marker Pax7, and b-FGF in the MDSC group. Also, higher expression of myogenin and VEGF were seen in the MDSC group at both 4 and 8wk time points. The paracrine effect of donor cells on host cells likely contributed to the differences found invivo between the groups. This approach for the rapid creation of highly-cellularized constructs with soft tissue like mechanics offers an attractive methodology to impart cell-derived bioactivity into scaffolds providing mechanical support during the healing process and might find application in a variety of settings.

Synthesis and evaluation of bio-based elastomer based on diethyl itaconate for oil-resistance applications

Bio-based elastomer poly(diethyl itaconate-co-isoprene) (PDEII) was designed and synthesized by redox-initiated emulsion polymerization from diethyl itaconate and isoprene with mass ratio of 20:80, 40:60, 60:40 and 80:20. The number-average molecular weights of PDEII exceeded 140000 with relatively high yields. The physical properties of PDEII, such as glass transition temperatures and thermostability, were comparable with conventional synthetic elastomers and can be readily tuned by varying the ratio of diethyl itaconate to isoprene. The interaction between silica and PDEII macromolecules was effectively enhanced with the increase of diethyl itaconate content by endowing high polarity. The oil-resistance relevant properties of silica/ PDEII80 (80% diethyl itaconate, 20% isoprene) such as retention of tensile strength, retention of elongation at break and change in volume even surpass those of silica/NBR 240S after soaked in ASTM 3# oil at different temperatures.

Elastomeric foam prepared by supercritical carbon dioxide

ABSTRACTBiodegradable elastomer poly[(1,4‐butylene terephthalate)‐co‐(1,4‐butylene adipate)] foam was successfully prepared using supercritical CO2. The elastomer foam has closed and uniform cell structure with density about 90 g/L. Narrow size distribution with average cell diameter 32 μm were obtained. The foamed balls show rubbery properties and can recover well (&gt;90%) to their original shape quickly after releasing press stress. Cell growth needs to take place at melting state where the migration and orientation of polymer chains are permanently kept without remained force of springback. Some unique phenomena were observed during foaming the elastomer: post‐expansion (about 40%) was obtained after removing the foamed samples from a cylinder mold, which results in forming a ball rather than a cylinder like the mold. This phenomenon was explained by the lower glass transition temperature of the elastomer, in which residual CO2 foam continuously in the room temperature; and “memory” of internal strength. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44354.

Solvent-Assisted Gel Printing for Micropatterning Thin Organic-Inorganic Hybrid Perovskite Films.

While tremendous efforts have been made for developing thin perovskite films suitable for a variety of potential photoelectric applications such as solar cells, field-effect transistors, and photodetectors, only a few works focus on the micropatterning of a perovskite film which is one of the most critical issues for large area and uniform microarrays of perovskite-based devices. Here we demonstrate a simple but robust method of micropatterning a thin perovskite film with controlled crystalline structure which guarantees to preserve its intrinsic photoelectric properties. A variety of micropatterns of a perovskite film are fabricated by either microimprinting or transfer-printing a thin spin-coated precursor film in soft-gel state with a topographically prepatterned elastomeric poly(dimethylsiloxane) (PDMS) mold, followed by thermal treatment for complete conversion of the precursor film to a perovskite one. The key materials development of our solvent-assisted gel printing is to prepare a thin precursor film with a high-boiling temperature solvent, dimethyl sulfoxide. The residual solvent in the precursor gel film makes the film moldable upon microprinting with a patterned PDMS mold, leading to various perovskite micropatterns in resolution of a few micrometers over a large area. Our nondestructive micropatterning process does not harm the intrinsic photoelectric properties of a perovskite film, which allows for realizing arrays of parallel-type photodetectors containing micropatterns of a perovskite film with reliable photoconduction performance. The facile transfer of a micropatterned soft-gel precursor film on other substrates including mechanically flexible plastics can further broaden its applications to flexible photoelectric systems.