Alignment materials with controllable anchoring energy

New polymers with photo‐controllable anchoring energy and tunable pretilt angle within 90°–0° range for nematic liquid crystals alignment were developed. The functional properties of polymers are provided by the effect of photoinduced planar alignment and the presence of side hydrocarbon chains in macromolecules that create a homeotropic alignment effect. Applying photosensitive alignment layers based on polymers with side benzaldehyde and hydrocarbon groups, fabrication of optical devices with refractive index gradient, uniform cell gap, and low operation voltage is possible. The developed materials are suitable for simple fabrication of tunable liquid crystal lenses.     

可注射性骨修复材料不饱和聚磷酸酯的光引发交联聚合

通过凝胶含量的测定，研究了紫外光引发不饱和聚磷酸酯（UPPE）与N-乙烯基吡咯烷酮的共聚交联反应，结果表明：加入光引发剂能够显著增加凝胶含量，安息香乙醚（BE），安息香（BN），2，2-二乙氧基苯乙酮的引发活性较高,光引发剂浓度较低时，增加光引发剂的含量能够显著提高单位时间内的凝胶生成率，但含量过大反而降低凝胶生成率．BN、BE的适宜浓度分别为2．4E^-5（mol／gUPPE）及0．6E^-5（mol／gUPPE）,光照较短时间内，UPPE分子量为5960g／mol的体系具有最高的凝胶生成率，但由于粘度的影响，光照2min后其凝胶生成率低于UPPE分子量为4040 g／mol的体系,表层对紫外光的吸收降低了光能量，导致深层交联聚合反应速度降低，1.5mm厚试样通过延长曝光时间，凝胶含量可与1.0mm厚试样接近，6.0mm试样曝光24min后底层仍不能固化。     

Preparations and oil absorptivities of poly(stearyl methacrylate-co-cinnamoyloxyethyl methacrylate) and PET nonwoven fiber photocrosslinked with it

Cinnamoyloxyethyl methacrylate (CEMA) was synthesized by the reaction of cinnamoyl chloride (CMC) and 2-hydroxyethyl methacrylate (HEMA). Its copolymers with stearyl methacrylate (SMA) were synthesized using benzoyl peroxide (BPO) as an initiator. The synthesized copolymers, poly(SMA-co-CEMA)s (PSCMAs), were photocrosslinked by UV light irradiation. The structures of the products were confirmed by IR and NMR spectroscopies. The thermal properties of the synthesized polymers were determined by DSC. The crystalline melting temperature of crosslinked PSCMA was decreased with increasing CEMA content in the feed. The oil absorptivities of the synthesized polymers were evaluated by the ASTM method (F726-81). The highest oil absorptivity of crosslinked PSCMA on poly(ethylene terephthalate) (PET) nonwoven fiber (NWF) was 610% in 10% crude oil diluted with toluene when the mol percentage of CEMA to SMA in the feed was 7.5. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2349–2357, 1999     

光交联丝素蛋白水凝胶的蓝光引发体系

针对再生丝素蛋白水凝胶生物活性、凝胶效率及凝胶强度三者难以兼具的问题,用樟脑醌(CQ)、核黄素磷酸钠(FMN)、曙红Y(EY)及姜黄素4种生物相容的光敏剂,分别与二芳基六氟磷酸碘鎓盐(DPI)构成丝素蛋白水凝胶的高效蓝光交联引发体系。借助紫外分光光度计和光差示扫描量热法研究了4种光引发体系的光谱吸收特性和蓝光引发效率,采用光流变系统研究了光交联丝素蛋白的凝胶化行为。结果表明:CQ/DPI、EY/DPI体系均可作为自由基聚合以及丝素蛋白光交联反应的良好蓝光引发体系,该蓝光引发体系诱导丝素蛋白酪氨酸残基自由基间的偶合反应是丝素蛋白光交联反应的主要机制;以EY/DPI体系引发低浓度丝素蛋白光交联反应可在短时间(10 min)内实现较高强度丝素蛋白水凝胶的制备。     

Photosensitive polymers: Synthesis,characterization, and photocrosslinking properties of polymers with pendant α,β-unsaturated ketone moiety

Acrylate and methacrylate monomers with the photodimerizable α,β-unsaturated ketone moiety, such as 4-cinnamoylphenyl, 4-(4-methoxycinnamoyl)phenyl, 4-(4-nitrocinnamoyl)phenyl, or 4-(4-chlorocinnamoyl)phenyl, were prepared and homopolymerized using benzoyl peroxide as the initiator at 70°C in methyl ethyl ketone. The poly(meth)acrylates were characterized by ultraviolet, infrared, ¹H-nuclear magnetic resonance (NMR), and ¹³C-NMR spectra, and gel permeation chromatography. Their thermal properties were studied by thermogravimetric analyses in air and nitrogen, and differential scanning calorimetry. The photocrosslinking properties of the polymers were investigated as thin films and in solution in the presence and absence of sensitizer. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2111–2120, 1998     

Novel UV-autocurable methacrylo-urethane polymeric films derived from m-digallic acid: Preparation and characterization

A new acrylo-urethane film polymer was obtained from methacrylic m-digallic acid derivatives. The product was attained either by thermo- or photopolymerization, and the films were characterized by chemical and spectroscopic methods. Other studies of the properties of these polymers were also performed. The main characteristics found were brief curing times achieved with no photoinitiators, good thermal properties, and optical activity. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2575–2583, 1998     

Syntheses and characterization of photocrosslinkable poly(amic acid-co-urea)s with diazoresin

To improve the transparency, flexibility, and solubility of polyimide, and to fabricate a negative working photoresist, polyamic acid, polyurea, and poly(amic acid-co-urea) in various contents were synthesized. Photosensitive diazoresin was synthesized and was used as the photocrosslinking agent. Characteristics of the polymers were identified by using IR, EA, DSC, TGA, and UV. From dissolution capabilities and thermal properties of the polymers, we chose the most suitable polymer PA25 as the main resin of the negative photoresist. The mixture of the polymer and diazo resin can be used as a negative photoresist. Optical characteristics of the polymer and diazo resin were evaluated by UV spectrophotometer. It was found that the polymer and diazo resin showed different absorption wavelengths under UV exposure. Characteristics of the negative photoresist were investigated by using i-line lithography. A contact printing exposure technique was used in this investigation. Dissolution rate and resolution capability of the photoresist containing various amounts of diazo resin were evaluated. The optimal prebaking time, postbaking time, and SEM patterns of the negative photoresist were also investigated. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2401–2407, 1998     

Photoresponsive Functionalized Vinyl Cinnamate Polymers: Synthesis and Characterization

A series of functionalized vinyl cinnamate monomers were synthesized by the reaction of hydroxyethylmethacrylate and various substituted cinnamoyl chlorides. Electron donating and accepting functional groups such as −OCH₃, −Cl and −NO₂ were introduced at the para position of cinnamoyl chloride. Homopolymerization of the synthesized monomers were carried out in dimethylformamide using azobisisobutyronitrile as a free radical initiator at 80°C for 12h. The structures of the synthesized monomers and their polymers were characterized using Fourier transform infrared (FTIR), ¹H and ¹³C nuclear magnetic resonance spectroscopic techniques. Solid-state crosslinking of the above photosensitive polymers was studied by UV and FTIR spectroscopic techniques. The effects of various functional groups and the addition of sensitizer (benzophenone) on the photocrosslinking nature of the polymers were studied. The mechanism of photocrosslinking is a (2+2)π electron cycloaddition and not cis–trans isomerization in the functionalized polyvinylcinnamates. © 1997 SCI     

Polyethylene glycol/polyhedral oligomeric silsesquioxane as an in situ photocrosslinkable polymeric nanohybrid

Polyhedral oligomeric silsesquioxane (POSS)/poly(ethylene glycol) diacrylate (PEGDA) biodegradable nanohybrids were synthesized in which modified POSS was chemically incorporated into the polymer chain as reinforcing nanoparticles during a blue light photocuring process. First, POSS diacrylate (POSSA) was prepared by the simple reaction of POSS with acryloyl chloride and the product obtained was identified by Fourier transform infrared spectroscopy and ¹³C NMR. Second, POSSA was incorporated into the PEGDA matrix in various concentrations in the presence as well as the absence of a reactive diluent. Finally, some characterizations such as XRD, TEM, equilibrium swelling, viscoelastic behavior, mechanical properties and cytocompatibility tests were performed to evaluate the effectiveness of these nanoparticles within the PEGDA polymer matrix. The results revealed that POSSA acted as a crosslinking agent as well as an inorganic nanofiller to enhance the properties of PEGDA and also that the most effective content of these nanoparticles should be optimized in the range 1.5–3 wt%. This study suggests acrylated POSS as an effective nanoparticle to promote the efficiency of photocured nanohybrids used in medical applications. © 2020 Society of Chemical Industry