Effects of the chain length of crosslinking agents on the electro-optical properties of polymer-dispersed liquid crystal films

Kashima, Miki; Cao, Hui; Liu, Huijing; Meng, Qingyong; Wang, Ding; Li, Fasheng; Yang, Huai

doi:10.1080/02678290903568495

Cited by 49 publications

(15 citation statements)

References 15 publications

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“…Recently, poly(ethylene glycol) (PEG) hydrogels have attracted attention because of their advantageous features, such as non-toxicity, good water solubility, biocompatibility, and highly tunable properties; such hydrogels have been applied in drug delivery, wound healing, and various biomedical applications [5][6][7]. In addition, the crosslinking density of PEG hydrogels can be favorably tuned by changing the monomer (e.g., poly(ethylene glycol) methacrylate (PEGMA), poly(ethylene glycol) acrylic amide, vinyl alcohol, methyl methacrylate, and methacrylic acid) and/or the crosslinker (e.g., poly(ethylene glycol) diacrylate (PEGDA), poly(ethylene glycol) dimethacrylate (PEGDMA), poly(ethylene glycol) divinyl sulfones, and poly(ethylene glycol) diacrylamide) [5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Crosslinking Dynamics and Gelation Characteristics of Photo- and Thermally Polymerized Poly(Ethylene Glycol) Hydrogels

Sung

Lee

et al. 2020

Materials

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The crosslinking behaviors and gelation features of poly(ethylene glycol) (PEG) hydrogels were scrutinized during the UV and thermal polymerizations of mixtures of poly(ethylene glycol) methacrylate (PEGMA, monomer) and poly(ethylene glycol) dimethacrylates (PEGDMAs, crosslinkers). The real-time crosslinking behavior of the PEG hydrogels was quantified as a function of the UV irradiation time and reaction temperature during the UV and thermal polymerization, respectively, using real-time FT-IR spectrometry and rotational rheometry. The gelation characteristics of UV- and thermally crosslinked hydrogels were compared through the analysis of the gel fraction, swelling ratio, surface hardness, and the loading and release of rhodamine-B. The gelation properties of the cured hydrogel films were suitably correlated with the real-time rheological properties and crosslinked network state of the PEG mixtures. The crosslinking and gelation properties of the cured hydrogels could be optimally tuned by not only the molecular weight of the crosslinker but also the UV or thermal polymerization conditions.

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Section: Introductionmentioning

confidence: 99%

Crosslinking Dynamics and Gelation Characteristics of Photo- and Thermally Polymerized Poly(Ethylene Glycol) Hydrogels

Sung

Lee

et al. 2020

Materials

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“…The alignment of CNCs can be utilized to design complex hierarchical structures leading to directionality of mechanical properties and, when introduced, specific cell alignment (Walther et al, 2011; Bourget et al, 2013; Siqueira et al, 2017). This alignment also creates a larger barrier in one direction due to the aspect ratio of the CNCs, inhibiting the crosslinking of PEGDA in certain directions, leading to a general alignment of the crosslinked networks in the scaffolds (Lin et al, 2005; Kashima et al, 2010). This can be compared to the typical SLA technique, which exhibits random CNC orientation within the scaffold from the dispersion in the liquid polymer resin (Raman and Bashir, 2015; Palaganas et al, 2017; Jiang T. et al, 2019).…”

Section: Resultsmentioning

confidence: 99%

Gradient Poly(ethylene glycol) Diacrylate and Cellulose Nanocrystals Tissue Engineering Composite Scaffolds via Extrusion Bioprinting

Frost¹,

Sutliff²,

Thayer

et al. 2019

Front. Bioeng. Biotechnol.

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Bioprinting has advanced drastically in the last decade, leading to many new biomedical applications for tissue engineering and regenerative medicine. However, there are still a myriad of challenges to overcome, with vast amounts of research going into bioprinter technology, biomaterials, cell sources, vascularization, innervation, maturation, and complex 4D functionalization. Currently, stereolithographic bioprinting is the primary technique for polymer resin bioinks. However, it lacks the ability to print multiple cell types and multiple materials, control directionality of materials, and place fillers, cells, and other biological components in specific locations among the scaffolds. This study sought to create bioinks from a typical polymer resin, poly(ethylene glycol) diacrylate (PEGDA), for use in extrusion bioprinting to fabricate gradient scaffolds for complex tissue engineering applications. Bioinks were created by adding cellulose nanocrystals (CNCs) into the PEGDA resin at ratios from 95/5 to 60/40 w/w PEGDA/CNCs, in order to reach the viscosities needed for extrusion printing. The bioinks were cast, as well as printed into single-material and multiple-material (gradient) scaffolds using a CELLINK BIOX printer, and crosslinked using lithium phenyl-2,4,6-trimethylbenzoylphosphinate as the photoinitiator. Thermal and mechanical characterizations were performed on the bioinks and scaffolds using thermogravimetric analysis, rheology, and dynamic mechanical analysis. The 95/5 w/w composition lacked the required viscosity to print, while the 60/40 w/w composition displayed extreme brittleness after crosslinking, making both CNC compositions non-ideal. Therefore, only the bioink compositions of 90/10, 80/20, and 70/30 w/w were used to produce gradient scaffolds. The gradient scaffolds were printed successfully and embodied unique mechanical properties, utilizing the benefits of each composition to increase mechanical properties of the scaffold as a whole. The bioinks and gradient scaffolds successfully demonstrated tunability of their mechanical properties by varying CNC content within the bioink composition and the compositions used in the gradient scaffolds. Although stereolithographic bioprinting currently dominates the printing of PEGDA resins, extrusion bioprinting will allow for controlled directionality, cell placement, and increased complexity of materials and cell types, improving the reliability and functionality of the scaffolds for tissue engineering applications.

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“…Polymer-dispersed liquid crystals (PDLCs) have become the topic of considerable interest during the last decades, because of their potential applications such a smart windows, flexible displays, projection displays and holographic gratings [115][116][117][118][119]. The PDLC films have been widely studied as a candidate for the large area display because of the simplification of the preparation process and because their light transmittance is higher than conventional LCs in the absence of polarizer by the reason of their light scattering nature [120][121][122][123][124][125][126]. PDLC films are a mixed phase of micron-sized liquid crystal droplets, which are randomly dispersed inside a polymer matrix [127].…”

Section: Polymer Dispersion Of Blue Phasesmentioning

confidence: 99%

From a Chiral Molecule to Blue Phases

Kemiklioğlu¹

2018

Liquid Crystals - Recent Advancements in Fundamental and Device Technologies

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Chiral molecules play an important role in a wide range from biological structures of plants and animals to chemical systems and liquid crystal display technologies. These molecules were used in different research fields due to their opaqueness and iridescent colors changes as a function of the variation in temperature after their discovery by Lehman in 1889. The iridescent colors and different optical textures of cholesterol make it attractive for the new study field of cholesteric liquid crystals. The direction of the cholesteric liquid crystals generates a periodic helical structure depending on the chirality of molecules. This helical structure might be right or left handed configuration and it is very sensitive to the external conditions, such as chiral dopant concentration and temperature. The variation in a helical structure, which was induced by these external conditions, had a great attraction for the scientists working on the chirality in liquid crystals and their applications. This chapter will provide a general introduction not only about the chirality in nature and its application in liquid crystals, especially in blue phases but also about the trends in the stabilization of blue phases and the investigation of their electro-optical properties for advanced applications in display, photonic devices.

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Effects of the chain length of crosslinking agents on the electro-optical properties of polymer-dispersed liquid crystal films

Cited by 49 publications

References 15 publications

Crosslinking Dynamics and Gelation Characteristics of Photo- and Thermally Polymerized Poly(Ethylene Glycol) Hydrogels

Crosslinking Dynamics and Gelation Characteristics of Photo- and Thermally Polymerized Poly(Ethylene Glycol) Hydrogels

Gradient Poly(ethylene glycol) Diacrylate and Cellulose Nanocrystals Tissue Engineering Composite Scaffolds via Extrusion Bioprinting

From a Chiral Molecule to Blue Phases

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