Synthesis and characterization of side chain cholesteric liquid crystalline elastomers derived from chiral bisolefinic crosslinking units

In this work we prepared a nematic monomer (4′‐allyloxybiphenyl 4′‐ethoxybenzoate, M₁ ), a chiral crosslinking agent (isosorbide 4‐allyloxybenzoyl bisate, M₂ ) and a series of new side chain cholesteric liquid crystalline elastomers derived from M₁ and M₂ . The chemical structures of the monomers and polymers were confirmed by FTIR and ¹H NMR spectroscopy. The mesomorphic properties were investigated by differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy and X‐ray diffraction. The effect of the content of the crosslinking unit on phase behaviour of the elastomers is discussed. Polymer P₁ showed a nematic phase, P₂ –P₇ showed a cholesteric phase; P₆ formed a blue Grandjean texture over a broad temperature range 145–209.6°C, with no changed on the cooling. Polymers P₄ –P₇ , with more than 6?mol?% of chiral crosslinking agent, gave rise to selective reflection. Elastomers containing less than 15?mol?% of the crosslinking units displayed elasticity, reversible phase transition with wide mesophase temperature ranges, and high thermal stability. Experimental results demonstrated that, with increasing content of crosslinking agent, the glass transition temperatures first fell and then increased; the isotropization temperatures and mesophase temperature ranges decreased.     

Small‐Angle Neutron Scattering (SANS) Study of Magneto‐Vesicles

Small‐angle neutron scattering from magneto‐vesicles (MVs) prepared by extrusion was studied. Contrast variation allowed the determination of structure and sizes of the vesicles and the encapsulated magnetic nanoparticles, respectively. The results from MVs synthesized with a 0.3% volume fraction of citrate‐coated magnetic nanoparticles are compared to those of similarly prepared vesicles of the neutral lipid 1,2‐Dioleoyl‐sn‐Glycero‐3‐Phosphocholine (DOPC) (without magnetic particles), and magnetic particles not encapsulated in vesicles. It is observed that the bilayers of the as‐prepared MVs, and the encapsulated nanoparticles retain their structural properties, highlighting the suitability of the MVs for applications.     

Synergistic Effect of Oxalate and Ethylene Glycol on the Formation of SnO2 Rods

SnO₂ rods have been synthesized by using tin (II) chain‐like complexes as precursors in which oxalate and ethylene glycol act as co‐ligands. On the basis of experimental analysis, a reasonable formation mechanism of rods is discussed, which is further supported by Fourier transform infrared spectroscopy (FT‐IR). These results show that the synergistic effect of oxalate group and ethylene glycol plays an important role in the formation of long SnO₂ rods.     

Side chain liquid crystalline composites,occurrence of interdigitated bilayer smectic C phases

We report on the results of X-ray investigations in two series of polymer monomer composites, PM6Rm-33 and PMnR12-33, which consist of mixtures of achiral liquid crystalline side chain polymers and their monomers. These mixtures present a unique integration of monomer in the polymeric base which assists in modifying their properties and forming homogenous composites. X-ray measurements for all the investigated composites indicate the existence of bilayered smectic C phases (SmC₂). In several composites, the interlayer distance of the SmC₂ phase abnormally increases with cooling; this is associated with the aliphatic interdigitation at the tail-to-tail interface being more prominent when longer aliphatic tails are present.     

具有三核Cd(Ⅱ)簇单元和螺旋链的脯氨酸类单一手性金属-有机框架材料的合成、 结构和性质

在溶剂热反应条件下, 使用含氮辅助配体1,4-二(4-吡啶基)苯(1,4-DPB)和半刚性脯氨酸衍生物配体(R)-5-(2-羧基吡咯烷-1-羰基)间苯二甲酸[(R)-H₃PIA]或(S)-5-(2-羧基吡咯烷-1-羰基)间苯二甲酸[(S)-H₃PIA]与Cd²⁺构筑了单一手性金属-有机框架材料[Cd_1.5((R)-PIA)(1,4-DPB)_1.5]·0.75H₂O·xGuest(1-D)和[Cd_1.5((S)-PIA)(1,4-DPB)_1.5]·0.75 H₂O·xGuest(1-L). 配合物1-D和1-L呈具有开放孔道的三维柱层式框架结构, 含有三核镉簇单元 Cd₃(CO₂)₆与两种螺旋链构建的波浪形Cd-PIA层. 分别对上述化合物进行了粉末X射线衍射、 热重分析、 圆二色谱和荧光光谱等测试. 测试结果显示配合物1-D和1-L都是以纯晶体的形式存在, 2种配合物的热失重曲线接近, 圆二色谱有明显的正负吸收峰, 符合其对映体的结构特征.     

On the normalized Laplacian of Möbius phenylene chain and its applications

Let denote a molecular graph of linear [n] phenylene with n hexagons and n squares, and let the Möbius phenylene chain be the graph obtained from the by identifying the opposite lateral edges in reversed way. Utilizing the decomposition theorem of the normalized Laplacian characteristic polynomial, we study the normalized Laplacian spectrum of , which consists of the eigenvalues of two symmetric matrices ℒ _R and ℒ _Q of order 3n. By investigating the relationship between the roots and coefficients of the characteristic polynomials of the two matrices above, we obtain an explicit closed-form formula of the multiplicative degree-Kirchhoff index as well as the number of spanning trees of . Furthermore, we determine the limited value for the quotient of the multiplicative degree-Kirchhoff index and the Gutman index of .     

碳酸乙烯酯溶剂中丙烯腈的聚合行为

以碳酸乙烯酯为溶剂,偶氮二异丁腈（AIBN）为引发剂,采用溶液自由基聚合的方法对丙烯腈(AN)均聚合、丙烯腈/衣康酸(AN/IA)二元共聚及丙烯腈/衣康酸/丙烯酸甲酯(AN/IA/MA)三元共聚合进行了研究。 考察了反应温度对丙烯腈均聚合,以及聚合单体浓度对丙烯腈共聚合的影响,在60 ℃合成了相对分子质量高于4.5×105、单体转化率高于85%的丙烯腈均聚物及共聚物。 采用正十二烷基硫醇（DDT）和甲酰基哌啶（FP）作为链转移剂,对AN均聚物、AN/IA及AN/IA/MA共聚物的相对分子质量进行调控,考察了链转移剂浓度对聚合物相对分子质量和单体转化率的影响。 结果表明,w(DDT)为0.25%时（以单体质量计）,聚合物相对分子质量可有效调节到1×105,而单体转化率保持在80%以上。     

高分子单链凝聚成与线团相互穿透的多链凝聚态

高分子单链凝聚态由于链内链结构单元间存在范德化吸引作用,高分子链呈打圈链构象,而多链凝聚态由于链内链单元间的吸引作用被与相互穿透的近邻链的单元间吸引作用所屏蔽,高分子链呈高斯链构象。本文简要介绍单链凝聚态试样的制备方法,单链单晶体、单链玻璃体、溶胀的单链高弹态拉伸等的实验观察,并提出从单链凝聚态到多链凝聚态的转变过程问题,即高分子线团的相互穿透过程,目前还缺少基础了解。     

Simulation of Complexes between a Charged Dendrimer and a Linear Polyelectrolyte with Finite Rigidity

Complexes comprising a 4th‐generation dendrimer with 32 positively charged end‐groups and an oppositely charged linear polyelectrolyte along with explicit counterions are studied in an athermal solvent using MC simulations. The excluded volume between monomers, the full Coulomb potential between charges and the bending energy of the chain bonds are taken into account. The chain flexibility parameter is varied in a wide range, including the limiting cases of rigid and flexible chains. As the chains become more rigid, they take locally extended conformations within the complex. The conformations of the condensed chains are described in terms of loops, trains, and tails. In the limit of strong electrostatic coupling and high rigidity, long chains show a release of tails from the complex.