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Diacetylene-Containing Polymers X. Poly(Hexa-2,4-Diynylene Alkandicarboxylates): Morphology and Properties

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Diacetylene-Containing Polymers X. Poly(Hexa-2,4-Diynylene Alkandicarboxylates): Morphology and Properties Revista de la Sociedad Química de México, Vol. 46, Núm. 1 (2002) 32-37 Investigación Diacetylene-Containing Polymers X. Poly(hexa-2,4-diynylene alkandicarboxylates): Morphology and Properties Angel R. Moreno,1 Juan G. Robledo,1 Ana María Mendoza,1 Miriam F. Beristain2 and Takeshi Ogawa2* 1 División de Estudios de Posgrado e Investigación, Instituto Tecnológico de Ciudad Madero, Juventino Rosas y Jesús Urueta S/N, Col. Los Mangos, Cd. Madero, Tamaulipas 89440, México 2 Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apartado Postal 70-360, CU, Coyoacán, México 04510, D.F. Recibido el 13 de junio del 2001; aceptado el 22 de enero del 2002 Abstract. In order to study the relationships between the chemical Resumen. Con el objeto de estudiar las relaciones entre estructura structure, properties and the morphology of diacetylene-containing química, propiedades y morfología de poliésteres alifáticos que con- aliphatic polyesters, a series of diacetylene-containing polyesters hav- tienen grupos diacetilénicos, se sintetizaron una serie de poliésteres ing hexa-2,4-diynylene groups were synthesized, and their chemical que contienen el grupo hexa-2,4-diinileno, y se estudiaron sus propie- properties and morphology were investigated. The crystallinity of dades químicas y la morfología de los mismos. La cristalinidad de these polyesters depended on the methylene chain length of the dicar- estos poliésteres dependió de la longitud de la cadena metileno de boxylic acids. According to DSC, all of these polymers had an endo- diácidos carboxílicos. El análisis de DSC demostró que todos los therm due to the melting of the crystalline part at around 60 ºC and a poliésteres tenían señal endotérmica alrededor de 60 ºC correspon- large exotherm due to the thermal polymerization in the amorphous diente a la fusión de la parte cristalina, y exotérmica arriba de 150 ºC state, which occurred above 150 ºC. The polymers were light-sensi- debido a la polimerización térmica de los grupos diacetilénicos en tive developing yellow to red colors on UV irradiation due to the for- estado fundido. Los polímeros fueron sensibles a la luz desarrollando mation of polydiacetylene network in the polymer films. The polydia- color amarillo a rojo por irradiación de luz UV. La irradiación pro- cetylene networks formed by UV irradiation degrade on prolonged longada en aire causó la degradación de los polidiacetilenos formados irradiation in air due to photo-oxidation, except in the case of polya- en los poliésteres, excepto en el caso del azelato. zelate. Palabras claves: Polímeros diacetilénicos, poliésteres, reticulación, Keywords: Diacetylene-containing polymers, polyesters, crosslink- polidiacetilenos. ing, polydiacetylenes. Introduction crystalline structure of the films, which are determined by the chemical structures of the DA-containing polymers. The reac- The solid state polymerization of diacetylenes is a well-known tions with halogens give 1,2,3,4-tetrahalobutadiene-containing example of topochemical polymerization in which monomer polymers [5]. crystals are converted to the corresponding polymer crystals Previously, a series of DA-containing polysebacates were [1] as shown in Fig. 1. However, because of their extremely synthesized and their chemical and physical properties were high crystallinity their processing into thin films with exce- reported [6, 7]. They were semicrystalline polymers and some llent optical quality is difficult, and this has been the vital dis- of them showed an extraordinary mechanical strength; for advantage for their nonlinear optical applications. One of the example, a film of poly(octa-3,5-diynylene sebacate) had a methods to obtain polydiacetylene thin films is to obtain pro- tensile strength of 250 MPa. The polymers developed a red- cessable polymers containing diacetylene units, and after pro- dish color upon irradiation with UV light or electron beams. cessing to thin films, the diacetylene groups are polymerized Therefore, mechanically strong polymer films containing by irradiation or heating to develop polydiacetylene networks unsaturated bonds are readily obtained. Polymer films having in the films as shown in Fig. 2. highly unsaturated carbon-carbon linkages are interesting ma- Diacetylene-containing polymers are interesting materials terials for applications in gas separation. Masuda and his for a variety of potential applications because of their reactive coworkers have reported oxygen permeability of poly(1,2-di- diacetylene (DA) groups, and many different types of DA- substituted acetylenes) which showed excellent results in oxy- containing polymers have been prepared [2, 3]. The DA gen permeability [8]. However, the permeability decreases groups can be cross-polymerized to obtain polydiacetylene considerably with time, due to oxidation of double bonds by (PDA)-containing films which exhibit third order nonlinear oxygen. Polydiacetylenes, on the other hand are much more optical susceptibility [4]. The reactivity of the DA groups to resistant to oxidation than polyacetylenes because of the triple form a PDA network in the polymer films depends on the bonds in the conjugation. Beckham and coworkers have stu- Diacetylene-Containing Polymers X. Poly(hexa-2,4-diynylene alkandicarboxylates): Morphology and Properties 33 R 3, 6) or recrystallized from hexane (4, 7, 8, 10). It is essential R C that these bisacetylenic monomers are absolutely pure in order C R C C C C C to obtain polyesters with high molecular weights. Table 1 C R C R C R shows characterization data of these bisacetylenic esters. C R C C C C C R C R C C C R C R C C R Polymerization. An oxidative coupling reaction was used for C C R C C C R polymerization. To 2 g of the monomer dissolved in 10 mL of C C C C C R hn R distilled o-dichlorobenzene, were added 10 drops of freshly R C C R C C R R Heat or distilled N,N,N’,N’-tetramethylethylenediamine and 0.085 g C R C C C C pressure copper (I) chloride which had been purified by washing with C C C R C C R R 20 % sulfuric acid, then by glacial acetic acid, finally by ace- R C C C C C C C tone. The system was gently bubbled with oxygen while stir- C R C R ring at 70 °C. The viscosity of the system rapidly increased R and in some cases stirring became no longer possible. The Monomer Crystal Polymer Crystal contents were poured into HCl-acidified methanol to precipi- Fig. 1. Polymerization of diacetylenes in the solid state. tate the polymer, which was rapidly filtered, washed with me- thanol and dried in vacuum at room temperature. Immediately after drying the polymers were again dissolved in chloroform, died gas separation of a diacetylene-containing polyimide sys- and reprecipitated in methanol. The polymers were light sensi- tem, observing an increase in the oxygen/nitrogen selectivity tive and they tend to crosslink during storage. Therefore, the [9]. polymers were kept in a dichloromethane solution, and reco- The main objective of this study is to investigate the rela- vered by reprecipitation before measurements. The polymers, tionships among morphology, chemical structure and optical poly(hexa-2,4-diynylene alcandicarboxylate)s are hereafter properties of the films containing PDA networks developed in abbreviated as 1-n, where the numbers of methylene groups of the films. The colors of these polymers containing PDA net- the alcohol (1 from propargyl alcohol) and dicarboxylic acids, works vary from pale yellow to deep blue depending on their respectively. chemical structure, which cannot be predicted. Therefore, it is worth scanning as many polymers as possible in the hope of Instrumentation. DSC and TGA were performed with a Du finding the best PDA-containing films for nonlinear optical Pont 2100 thermoanalyzer. The powder X-ray diffractometry applications. In this work, a series of DA-containing aliphatic was carried out on a Siemens D-500 diffractometer with Cu- polyesters based on the 2,4-hexadiynylene unit were synthesi- Ka radiation of 1.540 Å. The samples were prepared by preci- zed and their morphology and properties were investigated. pitating the polymer into methanol using somewhat dilute polymer solutions in order to obtain the polymers in the form of fibrous powders. Precipitation from concentrated solutions Experimental results in the precipitation of fibrous polymers. Degree of crystallinity was calculated from the difference between the Monomer synthesis. The bisacetylenic monomers were syn- total area and the amorphous area using the software from thesized by the reactions of different acid chlorides with pro- pargyl alcohol using triethylamine as an acid acceptor and dichloromethane as a solvent: xx xx xx C C C C xx xxx x C C C C xx xx xx C C C C xx xx xx C C C C C C xx xx xx C C C C xx xxx x C C C C xx xx xx C C C C xx xx Cl-CO(CH2)nCO-Cl + 2HCºC-CH2-OH C xxx xx x C C C C xxx xx x C C C C xxx xx x C C C C xxx xx x C C C C C C xxx xx x C C C C xxx xx x C C C C xxx xx x C C C C xx N Et3, CH 2Cl 2 ¾¾® HCºC-CH2-OCO(CH2)n-COO-CH2-CºCH A Cross-polymerization of where n is 2, 3, 4, 6, 7, 8 and 10. The chlorides, 2,3,4,7 and 8 Diacetylene groups hn or heat were supplied by Aldrich Chemical and distilled under reduced pressure before use. The chlorides 6 and 10 were pre- pared by the reaction of the corresponding acids with thionyl xxx xxx C C C C x xx xxx C C C C xxx xxx C C C C x xx xxx C C chloride. The reaction with propargyl alcohol was carried out C C C C xxx xxx C C C C x xx xxx C C C C xxx xxx C C C C x xx x in dry dichloromethane using triethylamine as an acid recep- C x xxx xx C C C C x xxx xx C C C C x xxx xx C C C C x xxx xx C C tor.
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