Characterization of the ladder polymerization of a crystalline cyclotetradiyne monomer

The polymerization of the cyclic tetradiyne monomer, [? (CH₂) ₂? C?C? C?C? (CH₂)₂? ]₄, containing interstitial chloroform has been investigated using Raman and Fourier-transform infrared spectroscopy and x-ray diffraction techniques. A loss of crystallographic register between chains occurs during the polymerization reaction, although crystalline order in the chain-axis projection is retained. These studies indicate that 50 Mrad of ⁶⁰Co γ-ray irradiation produces 1,4-addition polymerization at most of the diacetylene functionalities. Unreacted diacetylene groups are present primarily, although not completely, in soluble oligomeric material. Infrared spectroscopy indicates that this low molecular weight material has a butatriene (cumulene) backbone structure rather than the acetylenic structure of the insoluble polymer.     

Solid-state polymerization of a cyclic diacetylene

Large polymeric single crystals of a unique ring-bridged polymer have been produced by the solid-state polymerization of a cyclic diacetylene (o,o′-diacetylenyldiphenyl glutarate). These crystals are of high thermal stability, metallic in appearance with an asbestos-like texture, infusible, and insoluble. Single-crystal x-ray diffraction investigation indicates that the polymer is monoclinic (probable space group C2/c or Cc) with a unit cell containing four monomer units of dimensions α = 20.8 Å, b = 8.0 Å, c = 9.7 Å, and β = 106°. Infrared spectra eliminate the previously suggested possibility that the solid-state reactivity of the above monomer corresponds to either reaction of the carbonyl function with the acetylenic bond or the cleavage of the ester linkage. Diffraction, dichroism, and Raman spectral studies indicate instead that the reaction proceeds by 1,4-addition polymerization at the diacetylene group to produce a trans–trans polymer of structure where the curved lines represent the di-(o-phenyl)-glutarate linkages which are on opposite sides of the chain for adjacent monomer units.     

Stability of hydrogen bonds upon polymerization and color transition of diacetylenes: An FTIR spectroscopy study

FTIR spectra (400–7500 cm⁻¹) have been recorded for polycrystalline films and single crystals of the diacetylene 4BCMU in the monomer, blue and red polymer states, and of 3BCMU monomer. Particular attention was paid to the amide bands associated to the urethanes in the side groups, which form one-dimensional H-bond linear chains quite similar to those found in peptides and proteins. The positions and strengths of these absorptions are practically unchanged by polymerization or blue to red polymer color transition. This suggests that the H-bond linear chains are the main constitutive interactions in these crystals, and that the conjugated parts must and do “adapt” to the unchanged H-bond lines. No evidence of side group disordering was observed at the irreversible blue to red transition in poly-4BCMU crystal.     

Defects in polydiacetylene single crystals. II. Dislocations in pTS

The structure of single crystals of a substituted diacetylene polymer (pTS) has been investigated by using transmission electron microscopy. It has been found that edge dislocations with Burgers vector parallel to the chain direction are present at a density of up to 10¹³ m^?2. It is suggested that the dislocations may be present first of all in the monomer crystals and become locked into the monomer structure during polymerization. It has been found that the dislocations have a tendency to line up in rows perpendicular to the chain direction and when the density of the dislocations in a row is sufficiently high a small?angle grain boundary can be formed. A possible structure for the dislocations on a molecular level is suggested and the effect of the presence of the dislocations upon the polymerization behavior, mechanical properties, and electric properties is discussed.     

ODMR and triplet state kinetics of a carbazolyl substituted diacetylene crystal

Carbazolyl substituted diacetylene (DCH) monomer crystals showing phosphorescence from four traps have been investigated by optically detected magnetic resonance (ODMR) at 1.2 K. These localized triplet states are attributed to the carbazolyl side groups. Their population and depopulation rate constants and zero field splitting parameters (0.097 <|D|< 0.1002 cm^?1; 0.0068 <|E|<0.0105 cm^?1) have been determined. The results suggest that the traps are disturbed substituents. The proposed interaction of the trap states with an exciton band at 23926 cm^?1 is supported by temperature dependent lifetime measurements.     

Dielectric properties of single crystals of the substituted diacetylene pTS: effect of the solid-state polymerization and phase transitions

Dielectric permittivities of the polymerizable organic solid, pTS diacetylene have been measured between 115 and 330 K in the directions parallel and perpendicular to the direction of polymer chain growth. The upper phase transition in monomer, polymer and mixed crystals at various stages of the solid-state polymerization manifests itself as a maximum in the temperature dependence of ε measured in the direction parallel to the molecular stacks, being particularly well pronounced in fully polymerized crystals. The transition was identified as an antiferroelectric one, the sublattice polarization being most probably the order parameter. The lower phase transition could be observed only in monomer and monomer-rich crystals as a shoulder on the ε(T) dependence. This transition could be detected only in the crystals containing less than ≈ 10–15% of polymer. The dielectric permittivity was found to be independent of frequency up to 3 GHz. The polymerization results in changes of the dielectric permittivity. In samples where the direction of measurements coincides with the b axis, these changes follow the monomer-polymer conversion curve.     

Pressure dependence of phase transitions in two diacetylene crystals

The phase transitions which occur in a diacetylene polymer crystal (PTS) at 195 K and a diacetylene monomer crystal (DCH) at 142 K have been studied as a function of pressure. For the second-order phase transition in PTS the pressure dependence of the transition temperature was found to be less than 0.05 K MPa^?1; for the first-order transition in DCH it was 0.63 ± 0.08 K MPa^?1.     

Photosensitized Solid-state Polymerization of Diacetylenes in Nanoporous TiO2 Structures

In situ topochemical polymerization of two diacetylene monomers within nanoporous TiO₂ thin films was carried out under visible light irradiation. One of the monomers used contains a carboxylic acid group, which could help to link the monomer onto the TiO₂ surface covalently. UV-Vis absorption and Raman studies showed that both monomers were successfully photopolymerized. These results suggest that the covalent linkage of the diacetylene to the nanoparticle through the carboxylic acid group is not needed. Since photopolymerization of diacetylene is typically induced by excitation of the monomer at λ< 300 nm, the observed red shift of the photopolymerization wavelength is attributed to the photosensitization effect of TiO₂. The morphological study of the polydiacetylene/TiO₂ nanocomposite revealed that the diacetylene monomers were polymerized in the vicinity of the TiO₂ nanoparticles. This is attributed to the fact that the electron-transfer process occurs at the interface of nanocrystalline TiO₂ (nc-TiO₂) and the diacetylene monomer and the polymerization is expected to be initiated near the nc-TiO₂ surface. Photopolymerization of the carboxylated diacetylene monomer with other oxides nanoparticles, such as ZnO and SiO₂ was also investigated.     

Dielectric and pyroelectric properties of disubstituted diacetylenes

The dielectric and pyroelectric properties of monomer and polymer single crystals of substituted diacetylenes carrying polar side groups are presented for four examples: NP/4-MPU, TS/FBS, DNP and IPUDO. Large and anisotropic permittivities are generally observed. The symmetrically disubstituted diacetylenes IPUDO and DNP show spontaneous electric polarization despite of their symmetric molecular unit in polymer and/or monomer crystals at room or low temperature, respectively. Polar crystals of the unsymmetrically substituted diacetylenes NP/4-MPU and TS/FBS can be grown from appropriate solvents. However, polymorphism is an obstacle to a systematic tailoring of dielectric properties of diacetylene single crystals.     

Synthesis and characterization of a novel soluble reactive ladder‐like polysilsesquioxane with side‐chain 2‐(4‐chloromethyl phenyl) ethyl groups

A new kind of soluble structure‐ordered ladder‐like polysilsesquioxane with reactive side‐chain 2‐(4‐chloromethyl phenyl) ethyl groups ( L ) was first synthesized by stepwise coupling polymerization. The monomer, 2‐(4‐chloromethyl phenyl) ethyltrichlorosilane ( M ), was synthesized successfully by hydrosilylation reaction with dicyclopentadienylplatinum(II) chloride (Cp₂PtCl₂) ­catalyst. Monomer and polymer structures were characterized by FT‐IR, ¹H‐NMR, ¹³C‐NMR, ²⁹Si‐NMR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), vapor pressure osmometry (VPO) and X‐ray diffraction (XRD). This novel reactive ladder‐like polymer has promise potential applications as initiator for atom transfer radical polymerization, and as precursor for a variety of advanced functional polymers. Copyright © 2001 John Wiley & Sons, Ltd.     

Synthesis and application as polymer electrolyte of hyperbranched polyether made by cationic ring‐opening polymerization of 3‐{2‐[2‐(2‐hydroxyethoxy)ethoxy]ethoxymethyl}‐3′‐methyl‐oxetane

A novel cyclic ether monomer 3‐{2‐[2‐(2‐hydroxyethoxy)ethoxy]ethoxy‐methyl}‐3′‐methyloxetane (HEMO) was prepared from the reaction of 3‐hydroxymethyl‐3′‐methyloxetane tosylate with triethylene glycol. The corresponding hyperbranched polyether (PHEMO) was synthesized using BF₃·Et₂O as initiator through cationic ring‐opening polymerization. The evidence from ¹H and ¹³C NMR analyses revealed that the hyperbranched structure is constructed by the competition between two chain propagation mechanisms, i.e. active chain end and activated monomer mechanism. The terminal structure of PHEMO with a cyclic fragment was definitely detected by MALDI‐TOF measurement. A DSC test implied that the resulting polyether has excellent segment motion performance potentially beneficial for the ion transport of polymer electrolytes. Moreover, a TGA assay showed that this hyperbranched polymer possesses high thermostability as compared to its liquid counterpart. The ion conductivity was measured to reach 5.6 × 10^?5 S/cm at room temperature and 6.3 × 10^?4 S/cm at 80 °C after doped with LiTFSI at a ratio of Li:O = 0.05, presenting the promise to meet the practical requirement of lithium ion batteries for polymer electrolytes. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3650–3665, 2006     

Synthesis and characterization of poly(cyclohexane 2,2-dipropargyl-1,3-propylene ketal) containing double spiro structure

The Polymerization was carried out by MoCl₅ and WCl₆ associated with various organo-metallic cocatalysts. MoCl₅-based catalysts were found to be more effective. Polymerization of monomer containing a spiro structure proceeded rapidly to reach 80% yield within 2 h at 30°C. Polymerization of monomer led to a soluble, purple colored polymer with number average molecular weight (M_n) of 50000. Elemental analysis, ¹H-NMR, ¹³C-NMR, IR, and UV-visible spectra of the resulting polymer indicated that the polymer contains alternating double and single bonds along the polymer backbone and a cyclic recurring unit with a double spiro structure. In addition, the polymer had good oxidative and thermal stability and good solubility in common organic solvents. © 1995 John wiley & Sons, Inc.     

Synthesis of ladder polymers containing polydiacetylene backbones connected with methylene chains and their optical properties

The polymers consisting of polydiacetylene (PDA) backbones were obtained from the novel monomer derivatives, R CC CC R′ CC CC R [where R =  (CH₂)₄OCONHCH₂COOC₄H₉, R′ =  (CH₂)_n ; n = 2, 4, 8] [4BCMU4A(n)], in which linear methylene chain is sandwiched between two diacetylene moieties by solid-state 1,4-addition reaction. The polymerization process was investigated in detail by using spectroscopic techniques such as solid-state ¹³C-NMR, visible absorption, and IR absorption spectra. It was estimated that the polymerization of 4BCMU4A(8) and 4BCMU4A(4) takes place by two consecutive 1,4-addition reactions to form two PDA backbones, which constitute the two poles of the respective ladders. The bridging methylene chain length in the monomer was found to play a vital role as far as the polymerization process is concerned. Thus, the monomers with eight or four methylene units could form the ladder–PDAs by a two-step process, whereas the monomer containing two methylene units could only undergo one-step of 1,4-addition reaction. Further, it was found that the crystallinity of the polymers depends on the methylene chain length in the monomers, 4BCMU4A(8) being the most crystalline of all. These structural features strongly affect their absorption spectra. The third-order nonlinear optical susceptibilities (χ⁽³⁾) for these polymers were measured using third-harmonic generation method. The largest χ⁽³⁾ value obtained was 3.4 × 10⁻¹¹ esu for the poly[4BCMU4A(8)] thin film in resonant region. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3537–3548, 1999     

Transient photoconductivity of a polydiacetylene single crystal

Pulsed photoconductivity results are presented for single crystals of a fully-conjugated polymer, poly-2,4-hexadiyne-1,6-diol bis(p-toluene sulfonate). Carriers of both sign are observed and are found to have essentially identical action spectra with a photoconduction onset around 3 eV. Upper and lower limits could be placed on the charge carrier mobilities normal to the (011) crystallographic plain, which is roughly the polymer chain direction: 3 ? μ_e,h ? 10^?3 cm²/V s. The mobilities normal to the chain are about a factor of 10 less. The carrier lifetimes are about 0.5 μs for both holes and electrons but strongly dependent on the method of polymerization of the precursor monomer crystals.     

Synthesis and Thermoreversible Gelation Properties of Main‐Chain Poly(pyridine‐2,6‐dicarboxamide‐triazole)s

A series of main‐chain poly(amide‐triazole)s were prepared by copper(I)‐catalyzed alkyne–azide AABB‐type copolymerizatons between five structurally similar diacetylenes 1 – 5 with the same diazide 6 . The acetylene units in monomers 1 – 5 possessed different degrees of conformational flexibility due to the different number of intramolecular hydrogen bonds built inside the monomer architecture. Our study showed that the conformational freedom of the monomer had a profound effect on the polymerization efficiency and the thermoreversible gelation properties of the resulting copolymers. Among all five diacetylene monomers, only the one, that is, 1 ‐Py(NH)₂ which possesses the pyridine‐2,6‐dicarboxamide unit with two built‐in intramolecular H bonds could produce the corresponding poly(amide‐triazole) Poly‐(PyNH)₂ with a significantly higher degree of polymerization (DP) than other monomers with a lesser number of intramolecular H bonds. In addition, it was found that only this polymer exhibited excellent thermoreversible gelation ability in aromatic solvents. A self‐assembling model of the organogelating polymer Poly‐(PyNH)₂ was proposed based on FTIR spectroscopy, XRD, and SEM analyses, in which H bonding, π–π aromatic stacking, hydrophobic interactions, and the structural rigidity of the polymer backbone were identified as the main driving forces for the polymer self‐assembly process.     

Topochemical polymerisation of assembled diacetylene macrocycle bearing dibenzylphosphine oxide in solid state

Novel diacetylene macrocycles 1 and 2 bearing dibenzylphosphine oxide were synthesised via Eglinton acetylenic intramolecular coupling. The X-ray analysis of crystals of macrocycles 1 and 2 demonstrated that the better-aligned tubular supramolecular structure was formed in macrocycle 1 than in macrocycle 2, which provided the possibility of diacetylene topochemical polymerisation in solid state of macrocycle 1. UV–vis, Raman spectroscopy and X-ray analysis indicated that the crystals of macrocycle 1 could undergo topochemical diacetylene polymerisation only on their surface by light irradiation; differential scanning calorimetry, solid-state ¹³C NMR spectroscopy and solubility test demonstrated that the crystals of macrocycle 1 could undergo diacetylene topochemical polymerisation inside solid by heat. As expected, based on the topological analysis of crystal structure, the crystals of macrocycle 2 could not undergo diacetylene topochemical polymerisation either by light irradiation or heat.     

Solid-state polymerization of diacetylenes under the action of outside forces on crystalline monomer lattice

The polymerization of crystalline diacetylenes TS and DCH with different lattice structure was studied under high hydrostatic pressures (up to 4 kbar). It was shown that pressure increases the deformation of chain growing in monomer crystal. The features of such deformation depend on lattice structure that governs the influence of pressure on polymerization rate. We studied also polymerization of diacetylene HD crystals obtained in the pores of stretched polymer (PP). The field of polymer matrix influences the crystal state and the rate of polymerization. It was shown that the interaction of monomer crystals with the matrix leads to growth of more strained chains in these crystals.     

On the relationship of optical absorption energy and conversion during the polymerization of a crystalline diacetylene

Shifts in the optical absorption energy of polymer chains during polymerization of microcrystalline bis(p-toluene sulphonate) diacetylene are shown to be in accord with changes in the strain imposed on the chains by the mismatch of the monomer and polymer crystal lattices.     

Heat capacity of a polydiacetylene single crystal from 3 to 300 K

Heat capacities C_p of a polydiacetylene-bis(toluene sulfonate) single crystal and its monomer have been measured in the temperature range from 3 to 300 K. The temperature dependence of C_p for both monomer and polymer crystals differs from that for monoatomic solids. By applying a chain lattice model for a polymer crystal, the temperature dependence of the heat capacity can be described assuming a phonon density of states given by bending and stretching modes of the polymer backbone. With a combination of one-dimensional and three-dimensional elastic continuum approximations, the heat capacity has been calculated and a good fit to the data has been obtained. A small peak in C_p was detected at 161 K for the monomer and at 198 K for the polymer. This may be ascribed to a lower-temperature phase transition in the polydiacetylene crystals evidenced by previous x-ray and spectroscopic measurements.