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Measurement Techniques for Refractive Index and Second-Order Optical Nonlinearities
Published in Hari Singh Nalwa, Seizo Miyata, Nonlinear Optics of Organic Molecules and Polymers, 2020
Toshiyuki Watanabe, Hari Singh Nalwa, Seizo Miyata
Doisneau et al.299"300 reported " values of bimetallic ferrocenyl derivatives measured by EFISH at 1.34 and 1.9 ?m. These complexes are linked via an ethylenic bridge, where the ferrocenyl group acts as a donor and the oxazoline acts as a acceptor group. The sulfur to the oxazoline ring provides a bidentate ligand for further complex formation. Chirality is introduced in the ligand either at the sulfur or in the oxazoline ring that leads to noncentrosymmctric crystals for SHG. The measured and calculated " values are listed in Table 55. According to these results, the " values are enhanced significantly upon complexation. The highest " value of 1.23 X 10" esu was obtained for a Pd complex. Both Pd and Pt complexes showed larger " values than Ni complexes. A copolymer of PMMA having ferrocenyl- based chromophore (2) showed d33 = 4.39 pm/V and d3l = 1.38 pm/V.
Synthesis of Linear and Hyperbranched Stereoregular Aminopolysaccharides by Oxazoline Glycosylation
Published in Raphael M. Ottenbrite, Sung Wan Kim, Polymeric Drugs & Drug Delivery Systems, 2019
Jun-Ichi Kadokawa, Hideyuki Tagaya, Koji Chiba
The following attempt at the polymerization of another sugar oxazoline monomer was made to synthesize a non-natural-type aminopolysaccharide. The polymerization of a sugar oxazoline monomer, 4, with one hydroxy group at position 6 was carried out with CSA catalyst in 1,2-dichloroethane at reflux temperature [10]. The GPC chart of the reaction mixture, however, showed a bimodal profile consisting of a peak in the polymer region and a peak in the low molecular weight region; the former corresponded to the molecular weight of ca. 10,000 and the latter was located in the same region as the peak of monomer 4. These GPC data indicated that the reaction mixture contained two products. To isolate the former polymeric material from the reaction product, the mixture was poured into a large amount of 1,2-dimethoxyethane (DME). The GPC profile of the DME-insoluble part showed one peak in the polymer region, indicating that the product polymer could be isolated. On the other hand, the GPC profile of the DME soluble part showed a major peak in the low molecular weight region accompanied by a small peak in the polymer region.
Clay Mineral Catalysis of Redox, Asymmetric, and Enantioselective Reactions
Published in Benny K.G. Theng, Clay Mineral Catalysis of Organic Reactions, 2018
For both Cu-5 and Cu-6 complexes (with Laponite), the yield of products (3R, 3S, 4R, 4S) and their respective trans/cis ratios are influenced by the type of solvent used. Since the Cu-bis(oxazoline) complex is apparently immobilized as an almost square-planar structure, a reduction in solvent polarity would make it easier for the complex to approach the clay surface and establish close surface-complex interactions (Alonso et al. 2000; Fernandez et al. 2001). Interestingly, Bigi et al. (2001) also noted that the regioselective conversion of 2,4-di-tert-butylphenol and phenol to 4-tert-butylphenol over KSF montmorillonite was solvent-dependent. Furthermore, the trans/cis diastereoselectivity of the reaction between styrene and ethyl diazoacetate (Scheme 7.1), catalyzed by the Laponite-supported Cu complex with pyridine-oxazoline (6), is the reverse of that observed with the bis(oxazoline) complex (5) as ligand (Table 7.5). Using Cu2+-exchanged K10 montmorillonite as a catalyst, Fraile et al. (1996)also found that the normal trans/cis selectivity in solution was reversed, giving the cis-cyclopropane as the major product. The immobilization of enantioselective (chiral) catalysts on solid supports, including clay minerals, has been reviewed by Fraile et al. (2009b).
Design of comb-like poly(2-methyl-2-oxazoline) and its rapid co-deposition with dopamine for the study of antifouling properties
Published in Journal of Biomaterials Science, Polymer Edition, 2020
Ye Han Yan, Muhammad Atif, Ren Yong Liu, Hai Kun Zhu, Li Juan Chen
Biofouling significantly compromises a material’s surface performance and causes numerous problems such as bacterial infection, protein adsorption, and membrane fouling [1,2]. Surface modification by protein-resistant polymers is a common strategy to endow a material surface with an antifouling property [3,4]. Much work has been dedicated to building up hydrophilic and uncharged polymer brush surfaces, which creates highly hydrated surfaces and prevents protein adsorption onto material surfaces due to their outstanding water-trapping property [5]. The most commonly used protein-resistant polymers are poly(ethylene glycol) (PEG) [6,7], zwitterionic polymers [8,9], peptidomimetic polymers [10,11], and so on [12,13]. One of the more attractive candidates for such applications, poly(2-methyl-2-oxazoline) (PMOXA), is protein-resistant polymer because of its ability to sustain the formation of hydrogen-bonded water networks, and the formation of a hydration layer can prevent adsorption of protein on the surface of materials [14,15]. The synthesis of PMOXA can be performed by living cationic ring-opening polymerization (CROP), which allows for the design of architectures of PMOXA by incorporating functional terminal groups and initiators [16]. Numerous strategies have been developed to prepare PMOXA coatings to incorporate hydrophilicity and antifouling properties in material surfaces [17–21], and the anchoring of hydrophilic PMOXA on a material’s surface is receiving much attention.
Effect of end-grafted PEG conformation on the hemocompatibility of poly(styrene-b-(ethylene-co-butylene)-b-styrene)
Published in Journal of Biomaterials Science, Polymer Edition, 2019
Jianhua Lv, Jing Jin, Yuanyuan Han, Wei Jiang
Poly(ethylene glycol) (PEG) is a nontoxic, uncharged, and nonimmunogenic polymer with antibiofouling property [3, 4]. Hydrophilicity and steric repulsion of PEG endow surface with considerable hemocompatibility [5]. Grafting density and chain length of PEG are the two significant parameters to improve protein resistance and hemocompatibility [6, 7]. Different kinds of PEG conformations, such as pancaked-like, mushroom, and brushes, are formed depending on chain density [8, 9]. Polymer chains immobilized at one and both ends onto surfaces form polymer brushes with linear and looped conformations. Some researchers reported the preparation of antifouling coatings bearing polymer looped conformation using a mussel-inspired ABA triblock copolymer with catechol-anchoring groups [10] or poly[(N,N-dimethylacrylamide)15-co-(N-3,4-dihydroxyphenethyl acrylamide)2]-anchoring group [11] or looped poly-2-ethyl-2-oxazoline (PEOXA) with nitro-catechol groups [12]. However, the complicated triblock copolymers or the looped PEOXA are hard to synthesis and few publications focus on the looped conformation with two ends immobilized on plastic substrate to enhance hemocompatibility. Recently, a Monte Carlo simulation in our group reported that the surface smoothness and a dense impenetrable layer are the two significant characteristics of the looped polymer brush in resisting protein adsorption [13]. Experimentally, a mussel-inspired modification with dopamine self-polymerization is employed to modify substrate and further construct PEG with looped conformation [14].
Polyethylenimine-based nanocarriers in co-delivery of drug and gene: a developing horizon
Published in Nano Reviews & Experiments, 2018
Abbas Zakeri, Mohammad Amin Jadidi Kouhbanani, Nasrin Beheshtkhoo, Vahid Beigi, Seyyed Mojtaba Mousavi, Seyyed Ali Reza Hashemi, Ayoob Karimi Zade, Ali Mohammad Amani, Amir Savardashtaki, Esmail Mirzaei, Sara Jahandideh, Ahmad Movahedpour
Polymer chemistry has new things by business manufacturers, they produce poly(2-ethyl-2-oxazoline) with trade name Aquasolo. In addition, PEI has recently released a high degree of purity for Aquasolo, which is formed from 2-ethyl-2-oxazoline (>99.5% by GC) under compression conditions [17]. On the other hand, PEIs are polymer molecules that consist of repeating amine units and two aliphatic carbon. The branched PEI may have all the primary, secondary and tertiary amino groups, while the linear PEI has only the primary and secondary types. Besides, LPEI is solid at room temperature (near the melting point), while the BPEI is liquid (regardless of molecular weight). In addition, LPEI can be soluble in Boiling taste water with low pH, chloroform, ethanol and methanol [9,18].