Solid‐state polymerization of 2,3,6,7,10,11‐hexa(methacrylate) triphenylene

A new monomer, 2,3,6,7,10,11‐hexa(methacrylate) triphenylene (HMTP), and its crystals have been successfully synthesized, and the solid‐state polymerization under UV irradiation has been investigated. The photo polymerization of HMTP in solid was confirmed by the reduction of vinyl bonds in the FT‐IR and UV spectra of PHMTP in comparison with the corresponding spectra of its precursor. Thus, IR spectroscope was used to follow the polymerization of HMTP crystals under UV irradiation, and kinetic studies show a first‐order reaction with rate constant of 6.12 × 10^?3 min^?1. This value is slightly larger than that measured by the weight method. The polarizing optical microscope and X‐ray diffraction were used to study the crystal structure difference between the polymers and its monomer. The results show that the polymers' crystals obtained from photo polymerization kept the monomer crystal lattice. Because of strong overlap between the π‐electron of the triphenylene, the monomer and polymer crystals showed different fluorescence properties. All these results proved that the photo polymerization of HMTP crystals is governed by the packing structure of monomer molecules; in other words, this reaction is just lattice controlled polymerization. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1526–1534, 2005     

Four-center type photopolymerization in the crystalline state. V. X-ray crystallographic study of the polymerization of 2,5-distyrylpyrazine

Changes in crystal structure during polymerization and oligomerization of 2,5-distyrylpyrazine have been investigated by x-ray crystallography. The polymer and the oligomer as obtained are three-dimensionally oriented, and the directions of the three axes of the resultant crystals coincide with those of the original crystal. The space group of the products also agrees with that of the monomer. It is concluded that the polymer and the oligomer crystals approximately duplicate the molecular arrangement in the monomer crystal. The polymerization mechanism is discussed on the basis of the crystal structures.     

Solid-state polymerization of oxetanes. I. Lattice parameters and packing properties of the monomers

The crystallographic unit cells of melt-crystallized 3,3-bischloromethyloxetane and 3,3-bisbromomethyloxetane were determined by the Weissenberg method. The two isomorphous lattices are triclinic with two molecules in the unit cell. 3,3-Bisfluoromethyloxetane forms plastic crystals in the temperature range between ?36°C and +22°C, as shown by differential calorimetry and NMR broad-line spectroscopy. The Debye-Scherrer diagram and the general physical properties indicate the formation of a face-centered cubic lattice. No correlation between the lattice parameters of the monomer and polymer can be found On the basis of these results, the question is raised as to whether a topochemical polymerization of bishalomethloxetanes, i.e., a solid-state polymerization without destruction of the crystal lattice, can take place at all. The halomethyl side groups of the oxetanes can be shown to possess different conformations in monomer and polymer crystals, so that a conformational change of the groups and rearrangement of the molecules must take place during polymerization. Therefore, a topochemical mechanism for the solid-state polymerization of bishalomethyloxetanes seems to be impossible.     

Radiation-induced solid-state polymerization in binary systems. II. Relationship between polymerization rate and physical structure of binary systems

The radiation-induced solid-state polymerization of binary systems consisting of acrylic monomer (acrylamide, acrylic acid) and organic compounds was investigated. In the previous paper on binary systems the authors reported that the rate of polymerization increased in the solid state (eutectic mixture systems). The mechanism of rate increase has been investigated by examination of phase diagrams, viscosities, and surface tension of the binary systems. Viscosity and surface tension are the measure of the molecular interaction of the two-component systems. In addition, the effect of linear crystal growth rate and half maximum width of the x-ray diffraction diagram of the crystallization process were determined. The larger the molecular interaction between the two components, the slower the linear crystal growth rate of monomer. The size of the monomer crystal decreases and the dislocation density of the monomer crystals increases in systems with large molecular interaction. Consequently it can be concluded that the physical structure of a binary solid system is the most important parameter determining the rate increase of solid-state polymerization. Dislocation on the grain boundary is more important than defects inside of the crystal lattice. It was found that the acceleration of polymerization rate is large in binary systems with larger molecular interaction. In some systems such as organic acid—amide systems with strong hydrogen bonds, glassy phases may be formed in which monomer may readily polymerize at very low temperatures.     

Solid-state polymerization of oxetanes. II. Investigation of the growth of the polymer phase as related to the mechanism of polymerization

The radiation-induced solid-state polymerization of 3,3-bischloromethyloxetane (BCMO) was investigated by direct observation of the development of the morphology of the growing polymer phase in single crystals of the monomer. Electron microscopy shows that the polymerization gives rise to amorphous polymer in the first step. The polymer forms irregular platelets which aggregate into larger units without reflecting the crystalline order of the monomer. Subsequent to polymerization, the amorphous polymer crystallizes to the β-modification of poly-BCMO. If the partially polymerized crystals are extracted by solvents of the monomer, crystallization of the polymer is enhanced, and morphological artifacts arise which were previously mistaken for the true morphology of the “as polymerized” polymer. The copolymerization behavior of solid solutions of 3-ethyl-3-chloromethyloxetane (ECMO) and BCMO does not differ from the liquid bulk copolymerization with respect to copolymer composition, which is different from the composition of the monomer mixture. It is concluded that the polymer chains grow in noncrystalline zones as in a polymerization in the liquid state by which amorphous polymer is formed. No lattice control was observable in this solid-state polymerization.     

Four-center photopolymerization in the crystalline state. VIII. X-ray crystallographic study of the polymerization of some diolefinic compounds

The four-center photopolymerization of five diolefinic compounds has been investigated by x-ray crystal analysis. A common packing feature is found for the photopolymerizable crystals and all polymers are three-dimensionally oriented. Topotaxies observed are classified according to the coincidence of space group and the three crystal axes, between monomer and polymer. The polymerization mechanism is discussed on the basis of the topotaxies and it is concluded that the polymerization is lattice controlled over the whole reaction process.     

Self-assembly and solid-state photo polymerization of acrylamide crystal film

Solid-state polymerization has many advantages such as solvent-free, environmental friendly, less cost, and high purity of product. In this study, a crystal film of polyacrylamide was synthesized by solid-state polymerization. Firstly, gelatin was used for inducing acrylamide to form monomer crystal film through self-assembly in an aqueous solution. Then, the monomer crystal film underwent a photo-initiating polymerization to give the corresponding polymer crystal film. The structure of the crystal film was confirmed by Fourier-transformed infrared spectrometry, X-ray diffraction, microscopic melting point detector, and differential scanning calorimeter. The morphology was observed with scanning electron microscopy. The molecular weight was measured by gel permeation chromatography. It was found that a well-organized polyacrylamide crystal film was formed by controlling the synthetic conditions. The lattice size of the crystal changed very little before and after polymerization. The crystal film displayed a fibrous shape and was well-organized.     

The role of dislocations in the solid-state polymerization of monomers having conjugated triple bonds: A study of 2,4-hexadiyne-1,6-diol bis(p-toluene sulfonate)

The crystal structure of the monomer bis(p-toluene sulfonate) ester of 2,4-hexadiyne-1,6-diol (pT) is conducive from the viewpoint of both the separation distances and molecular configuration, to polymerization, irrespective of whether initiation is thermal, photochemical, or mechanical. The dislocations present in the monomer and polymer structures have been characterized by employing optical microscopic techniques. The slip system (102)[010] is found to be present in both monomer and polymer crystals but the (010)[001] system is found only in the monomer. On this basis a crystal structure for the monomer is proposed based on existing crystallographic information relating to the structure of the polymer. Dislocations are thought, on energetic grounds, to facilitate nucleation of product in the thermal polymerization but have no observable influence on the photoinduced reaction which proceeds homogeneously through the bulk.     

Preparation and thermal behavior of poly-p-phenylene diacrylic acid dimethyl ester

The photopolymerization behavior of p-phenylene diacrylic acid dimethyl ester (p-PDA Me) crystal and the thermal behavior of the resultant poly-p-PDA Me were investigated. From the kinetic study of polymerization at various temperatures a topochemical process via a stepwise mechanism was observed. Continuous change from monomer to polymer crystals was demonstrated by x-ray diffraction pattern and DSC analysis. Crystallinity of the reacting phase was maintained at an extremely high degree during the polymerization process in support of monomer crystal lattice control. Thermal study on as-polymerized poly-p-PDA Me crystal confirmed that the thermal reaction was a polymer crystal lattice-controlled depolymerization, which was followed by miscellaneous processes that involved vaporization, sublimation, and deterioration of the oligomeric or monomeric units of p-PDA Me. Thermal stability was dependent on the molecular weight. All the results are compared with those of four-center-type photopolymerization in the crystalline state.     

Monte Carlo simulation studies of the interfaces between polymeric and other solids as models for fiber-matrix interactions in advanced composite materials

As a coarse-grained model for dense amorphous polymer systems interacting with solid walls (i.e., the fiber surface in a composite), the bond fluctuation model of flexible polymer chains confined between two repulsive surfaces is studied by extensive Monte Carlo simulations. Choosing a potential for the length of an effective bond that favors rather long bonds, the full temperature region from ordinary polymer melts down to the glass transition is accessible. It is shown that in the supercooled state near the glass transition an “interphase” forms near the walls, where the structure of the melt is influenced by the surface. This “interphase” already shows up in static properties, but also has an effect on monomer mobilities and the corresponding relaxation behavior of the polymer matrix. The thickness of the interphase is extracted from monomer density oscillations near the walls and is found to be strongly temperature dependent. It is ultimately larger than the gyration radius of the polymer chains. Effects of shear deformation on this model are simulated by choosing asymmetric jump rates near the moving wall (large jump rate in the direction of motion, and a small rate against it). It is studied how this dynamic perturbation propagates into the bulk of the polymer matrix.     

Four-center type photopolymerization in the crystalline state. VI. Kinetic and structural study of the polymerization of p-phenylenediacrylic acid diethyl ester

The effect of temperature on the four-center type photopolymerization has been investigated for p-phenylenediacrylic acid diethyl ester over a wide temperature range including crystal transition point (56°C) and melting point (96°C) of monomer. With the elevation of temperature between ?50 and 15°C, the polymerization rate in the initial stage increased and the degree of polymerization decreased monotonously, while the rate in the later stage decreased above ?25°C. With irradiation at above 25°C, the monomer crystals became sticky, and the polymerization was suppressed at the stage of oligomerization with low conversion. This tendency was enhanced above the crystal transition point, giving mainly dimer in low yield. Above the melting point, only radical polymerization occurred with the aid of oxygen. The steric configuration of the products in the crystalline state was 1,3-trans with respect to the cyclobutane ring. Peaks in NMR spectra of all products were assigned to the protons involved in four compounds up to tetramer. Various results obtained have been interpreted in terms of the change, as a function of temperature, from a topochemical polymerization which proceeds under a control of the monomer lattice to a photoinitiated vinyl-type polymerization in the disordered state. It is concluded that a rigid crystal lattice is indispensable for the four-center type photopolymerization to proceed smoothly.     

Topochemical Polymerization of 1,3‐Diene Monomers and Features of Polymer Crystals as Organic Intercalation Materials

From the viewpoint of controlled polymer synthesis, topochemical polymerization based on crystal engineering is very useful for controlling not only the primary chain structures but also the higher‐order structures of the crystalline polymers. We found a new type of topochemical polymerization of muconic and sorbic acid derivatives to give stereoregular and high‐molecular weight polymers under photo‐, X‐ray, and γ‐ray irradiation of the monomer crystals. In this article, we describe detailed features and the mechanism of the topochemical polymerization of diethyl‐(Z,Z)‐muconate as well as of various alkylammonium derivatives of muconic and sorbic acids, which are 1,3‐diene mono‐ and dicarboxylic acid derivatives, to control the stereochemical structures of the polymers. The polymerization reactivity of these monomers in the crystalline state and the stereochemical structure of the polymers produced are discussed based on the concept of crystal engineering, which is a useful method to design and control the reactivity, structure, and properties of organic solids. The reactivity of the topochemical polymerization is determined by the monomer crystal structure, i.e. the monomer molecular arrangement in the crystals. Polymer crystals derived from topochemical polymerization have a high potential as new organic crystalline materials for various applications. Organic intercalation using the polymer crystals prepared from alkylammonium muconates and sorbates is also described.     

Contribution of monomer functionality and additives to polymerization kinetics and liquid crystal phase separation in acrylate-based polymer-dispersed liquid crystals (PDLCs)

Fundamental control of the polymerization behaviour of polymer-dispersed liquid crystals (PDLCs) is critical to the formation of high-performance devices by polymer-induced phase separation (PIPS). Previous PDLC research has shown that monomer functionality and additives such as surfactants or reactive diluents can impart significant changes to the electro-optical behaviour of a system, especially in acrylate-based materials. The influence of monomer functionality and additives on the polymerization kinetics and LC phase separation were examined in the formation of acrylate-based PDLCs. Real-time infrared (RTIR) spectroscopy was utilized to simultaneously monitor polymerization rate, double bond conversion and LC phase separation. In the formation of PDLCs by PIPS, increasing acrylate monomer functionality reduces the polymerization rate, overall double bond conversion and the extent of LC phase separation. Interestingly, the additives octanoic acid and N-vinylpyrrolidone (NVP) increase the polymerization rate but suppress LC phase separation. During PDLC formation, both octanoic acid and NVP enhance the solubility of the LC in the growing polymer matrix, reducing the rate of liquid-gel demixing and decreasing nematic fraction in PDLCs. As a non-reactive component, octanoic acid increases the polymerization rate by plasticizing the crosslinked polymerization. NVP, a reactive diluent added to decrease viscosity, increases polymerization rate through favourable copolymerization with acrylate monomer.     

Raman spectroscopic studies of the solid-state polymerization of diacetylenes. I. Thermal polymerization of 1,6-di-p-toluenesulfonyloxy-2,4-hexadiyne

The resonance Raman spectra of polymer chains in partially polymerized crystals of 1,6-di-p-toluenesulfonyloxy-2,4-hexadiyne are reported. The polymer chain distortion is deduced using the results obtained previously for fully polymerized samples under tensile strain. Changes in crystal lattice dimensions both parallel and lateral to the polymer chains are found to be important in interpreting the variations in frequency of the Raman-active vibrational modes. Further evidence is found for the resonant interaction of backbone and side-group vibrations reported previously. This interaction is affected by the lateral dimensional changes and is also sensitive to residual strain fields in the monomer crystals. It is not necessary in the interpretation of the Raman spectra to take any account of changes in polymer chain length during polymerization.     

Solid-Phase Radical Polymerization of Halogen-Bond-Based Crystals and Applications to Pre-Shaped Polymer Materials

Liquid vinyl monomers were converted into solid crystals via halogen bonding. They underwent solid-phase radical polymerizations through heating at 40 °C or ultraviolet photo-irradiation (365 nm). The X-ray crystallography analysis showed the high degree of monomer alignment in the crystals. The polymerizations of the solid monomer crystals yielded polymers with high molecular weights and relatively low dispersities because of the high degree of the monomer alignment in the crystal. As a unique application of this system, the crystalized monomers were assembled to pre-determined structures, followed by solid-phase polymerization, to obtain a two-layer polymer sheet and a three-dimensional house-shaped polymer material. The two-layer sheet contained a unique asymmetric pore structure and exhibited a solvent-responsive shape memory property and may find applications to asymmetric membranes and polymer actuators.     

Solid‐Phase Radical Polymerization of Halogen‐Bond‐Based Crystals and Applications to Pre‐Shaped Polymer Materials

Liquid vinyl monomers were converted into solid crystals via halogen bonding. They underwent solid‐phase radical polymerizations through heating at 40 °C or ultraviolet photo‐irradiation (365 nm). The X‐ray crystallography analysis showed the high degree of monomer alignment in the crystals. The polymerizations of the solid monomer crystals yielded polymers with high molecular weights and relatively low dispersities because of the high degree of the monomer alignment in the crystal. As a unique application of this system, the crystalized monomers were assembled to pre‐determined structures, followed by solid‐phase polymerization, to obtain a two‐layer polymer sheet and a three‐dimensional house‐shaped polymer material. The two‐layer sheet contained a unique asymmetric pore structure and exhibited a solvent‐responsive shape memory property and may find applications to asymmetric membranes and polymer actuators.     

Polymer nanostructure development of fluorinated and aliphatic monoacrylates in smectic liquid crystals via photopolymerization

To develop viable polymer stabilized liquid crystal systems, it is crucial to understand the factors that affect polymer nanostructure evolution. This work examines the influence of the photopolymerization of aliphatic and fluorinated monoacrylate monomer within a room temperature smectic liquid crystal (LC). Additionally, the effect of LC order on polymerization kinetics, monomer and polymer organization, and the effect of the polymer on LC properties have been examined. Through this work, insight has been gained regarding the impact that the introduction of a fluorinated monoacrylate monomer has on polymerization kinetics, LC organization, and monomer/polymer segregation and organization within a polymer/LC system. Fluorinated moieties lower the surface energy of the monomer to enhance segregation between the smectic layers of the LC as compared with an analogous aliphatic monomer. Additionally, the enhanced segregation significantly increases the polymerization rate in the smectic phase and drives the continued segregation of the fluorinated polymer during and after polymerization. Fluorination also leads to the formation of an ordered polymer nanostructure if polymerized in ordered LC phases. This ordering is particularly evident when the fluorinated monomer is polymerized in the smectic phase in which the monomer is organized between the smectic layers of the LC. In addition, the ordered polymer structure found with the fluorinated monomer in the smectic phase leads to continued birefringence above the clearing point of the LC due to surface interactions between the LC and the ordered fluorinated polymer. The continued birefringence offers an exceptional opportunity to examine how factors such as polymer molecular mass and UV light intensity affect the overall polymer morphology of these polymer/LC systems. As the initiator concentration and UV light intensity are decreased, longer polymer chains form lattice-type morphologies; whereas, shorter polymer chains form smoother morphologies that more closely mirror the texture of the LC smectic phase.     

Polymer nanostructure development of fluorinated and aliphatic monoacrylates in smectic liquid crystals via photopolymerization

To develop viable polymer stabilized liquid crystal systems, it is crucial to understand the factors that affect polymer nanostructure evolution. This work examines the influence of the photopolymerization of aliphatic and fluorinated monoacrylate monomer within a room temperature smectic liquid crystal (LC). Additionally, the effect of LC order on polymerization kinetics, monomer and polymer organization, and the effect of the polymer on LC properties have been examined. Through this work, insight has been gained regarding the impact that the introduction of a fluorinated monoacrylate monomer has on polymerization kinetics, LC organization, and monomer/polymer segregation and organization within a polymer/LC system. Fluorinated moieties lower the surface energy of the monomer to enhance segregation between the smectic layers of the LC as compared with an analogous aliphatic monomer. Additionally, the enhanced segregation significantly increases the polymerization rate in the smectic phase and drives the continued segregation of the fluorinated polymer during and after polymerization. Fluorination also leads to the formation of an ordered polymer nanostructure if polymerized in ordered LC phases. This ordering is particularly evident when the fluorinated monomer is polymerized in the smectic phase in which the monomer is organized between the smectic layers of the LC. In addition, the ordered polymer structure found with the fluorinated monomer in the smectic phase leads to continued birefringence above the clearing point of the LC due to surface interactions between the LC and the ordered fluorinated polymer. The continued birefringence offers an exceptional opportunity to examine how factors such as polymer molecular mass and UV light intensity affect the overall polymer morphology of these polymer/LC systems. As the initiator concentration and UV light intensity are decreased, longer polymer chains form lattice-type morphologies; whereas, shorter polymer chains form smoother morphologies that more closely mirror the texture of the LC smectic phase.     

热处理对聚己二酸丁二醋多晶结构和降解行为的影响

通过熔融结晶并结合退火处理方法得到多晶结构的聚己二酸丁二酯(PBA)及具有不同热历史的热力学稳定的a晶型,采用广角X射线衍射仪(WAXD)、原子力显微镜(AFM)和差示扫描量热仪(DSC)研究了PBA的多晶结构、晶体尺寸和结晶形貌,跟踪了退火处理PBA的生物降解行为.结果表明,分子链在相同晶格排列中围绕c轴空间取向的不...     

溶致性液晶高分子聚苯并■唑的合成和结构与性能研究

用对羟基苯甲酸甲酯（乙酯）为原料，合成了自缩聚型单体４ 羟基 ３ 胺基苯甲酸盐酸盐，在多聚磷酸介质中经溶液缩聚，制得高分子量的聚苯并唑（ＡＢＰＢＯ），在聚合后期观察到明显的溶致性液晶高分子所特有的搅拌乳光现象，经推膜及干喷湿纺技术得到了ＡＢＰ ＢＯ的薄膜和纤维．在甲基磺酸溶液中测定了ＡＢＰＢＯ的特性粘数，用Ｘ ｒａｙ平板照相及Ｘ ｒａｙ衍射、ＦＴＩＲ、ＴＧＡ、动态粘弹谱仪等测定和研究了ＡＢＰＢＯ薄膜和纤维的结构和性能，抗张强度为１５５ＧＰａ，抗张模量为９０ＧＰａ，在氮气中起始分解温度为６５７３℃．结果表明ＡＢＰＢＯ是一种高性能的半刚性的溶致性液晶高分子材料