Poly(1,3‐disila‐1,3‐diphenyl‐2‐oxaindane)– poly(dimethylsiloxane) block copolymers

The hydrolytic condensation of 1,3‐dichloro‐1,3‐disila‐1,3‐diphenyl‐2‐oxaindane under neutral conditions produced α'ω‐dihydroxy‐1,3‐disila‐1,3‐diphenyl‐2‐oxaindane (polymerization degree ≈ 4). The homofunctional condensation of α'ω‐dihydroxy‐1,3‐disila‐1,3‐diphenyl‐2‐oxaindane in a toluene solution and in the presence of activated carbon was performed, and dihydroxy‐containing oligomers with various degrees of condensation were obtained. Through the heterofunctional condensation of dihydroxy‐containing oligomers with α'ω‐dichlorodimethylsiloxanes in the presence of amines, corresponding block copolymers were obtained. Gel permeation chromatography, differential scanning calorimetry, thermomechanical analysis, thermogravimetry, and wide‐angle roentgenography investigations were carried out. Differential scanning calorimetry and roentgenography studies of the block copolymers showed that their properties were determined by the ratio of the lengths of the flexible and linear poly(dimethylsiloxane) and rigid poly(1,3‐disila‐1,3‐diphenyl‐2‐oxaindane) fragments in the macromolecular chain. At definite values of the lengths of the flexible and rigid fragments, a microheterogeneous structure was observed in the synthesized block copolymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1409–1417, 2002; DOI 10.1002/app.10335     

Synthesis and investigation of properties of silaoxadihydrophenanthrene‐diphenylsiloxane fragments containing block copolymers

The reaction of heterofunctional condensation of 1,1‐dichloro‐1‐sila‐2‐oxadihydrophenanthrene with dihydroxydiphenylsilane at various ratios of initial compounds in the presence of pyridine is investigated. α,ω‐Dihydroxysilaoxadihydrophenanthrene‐diphenylsiloxane oligomers with various degrees of condensation are obtained. Organosiloxane block copolymers with the regular arrangement of silaoxadihydrophenanthrene‐diphenylsiloxanes fragments in the main linear dimethylsiloxane chain are produced by the reaction of heterofunctional condensation of α,ω‐dihydroxysilaoxadihydrophenanthrene‐diphenylsiloxanes with α,ω‐dichlorodimethylsiloxanes in the presence of anhydrous pyridine, as an acceptor of hydrochloric acid. Thermogravimetry, differential scanning calorimetry, gel permeation chromatography, and wide‐angle X‐ray analysis are carried out on the synthesized block copolymers. The microheterogeneous structure of block copolymers is observed at definite values of the length of the flexible dimethylsiloxane chain by DSC and X‐ray investigation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 9–16, 2002; DOI 10.1002/app.10045     

Synthesis and investigation of the properties of poly(phenyl‐α‐naphthylsilylene)–dimethylsilylene copolymers

A Wurtz‐type reductive coupling reaction of dichlorophenyl‐α‐naphthylsilane was carried out in a mixture of toluene and o‐xylene in the presence of sodium and a catalytic amount of mercury; α,ω‐dichlorophenyl‐α‐naphthylsilylenes of various degrees of polymerization were obtained. Through the hydrolysis of α,ω‐dichlorophenyl‐α‐naphthylsilylenes, corresponding dihydroxy compounds were obtained. The heterofunctional polycondensation of α,ω‐dihydroxyphenyl‐α‐naphthylsilylenes with α,ω‐dichlorodimethylsilylenes was performed both without amines and in the presence of amines. Heterofunctional polycondensation without amines did not proceed with the formation of high molecular weight compounds because the cleavage of both ? Si? Si? and ?Si? O? Si? bonds took place during condensation. In the presence of amines, polysilylene–silylene copolymers were obtained. The synthesized copolymers were investigated with gel permeation chromatography, differential scanning calorimetry, roentgenography, and thermogravimetry. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1047–1056, 2002     

Redox initiation system of ceric salt and α,ω‐dihydroxy poly(dimethylsiloxane)s for vinyl polymerization

The redox system of ceric salt and α,ω‐dihydroxy poly(dimethylsiloxane) is used to polymerize vinyl monomers such as acrylonitrile and styrene to produce block copolymers. The concentration and type of α,ω‐dihydroxy poly(dimethylsiloxane) affects the yield and the molecular weight of the copolymers. The copolymers have about 20°C lower glass‐transition temperatures and much higher contact angle values than of the corresponding homopolymer of vinyl monomers, although the weight percent of α,ω‐dihydroxy poly(dimethylsiloxane) of the copolymers is in the range of 1–2%. © 2006 Wiley Periodicals Inc. J Appl Polym Sci 102: 2112–2116, 2006     

Arylenecyclosiloxane–dimethylsiloxane copolymers

The heterofunctional condensation reaction of 1,4‐bis(phenyldichlorosilyl)benzene with dihydroxydiphenylsilane at a 1:4 ratio of initial compounds in the presence of pyridine was investigated and tetrakis(hydroxydiphenylsiloxy)‐1,4‐bis(phenylsilyl)benzene was obtained. The heterofunctional condensation of the tetrakis(hydroxydiphenylsiloxy)‐1,4‐bis(phenylsilyl)benzene with organotrichlorosilanes at a 1:2 ratio of initial compounds in the presence of pyridine produced dichloro‐containing arylenecyclosiloxanes. The dichloro‐containing arylenecyclosiloxanes were obtained in one stage by successive heterofunctional condensation of 1,4‐bis(dichlorophenylsilyl)benzene with dihydroxydiphenylsilane and organotrichlorosilanes in a 1:4:2 ratio in the presence of pyridine. It was established that the yields of dichloro‐containing products were lower. Hydrolysis of dichloroarylenecyclosiloxanes in a neutral condition produced corresponding dihydroxy compounds. Heterofunctional polycondensation of dicloro(dihydroxy)arylenecyclosiloxanes with α,ω‐dihydroxy(bisdimethylamino)dimethylsiloxanes was used to obtain arylenecyclosiloxane‐dimethylsiloxane copolymers. Thermogravimetric, thermomechanical, and roentgenographic investigations of the synthesized copolymers were carried out. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3142–3148, 2001     

Synthesis and characterization of copolymers based on poly(butylene terephthalate) and ethylene oxide‐poly(dimethylsiloxane)‐ethylene oxide

A series of thermoplastic elastomers based on ethylene oxide‐poly(dimethylsiloxane)‐ethylene oxide (EO‐PDMS‐EO), as the soft segment, and poly(butylene terephthalate) (PBT), as the hard segment, were synthesized by catalyzed two‐step, melt transesterification reaction of dimethyl terephthalate (DMT) with 1,4‐butanediol (BD) and α,ω‐dihydroxy‐(EO‐PDMS‐EO). Copolymers with a content of hard PBT segments between 40 and 90 mass % and a constant length of the soft EO‐PDMS‐EO segments were prepared. The siloxane prepolymer with hydrophilic terminal EO units was used to improve the miscibility between the polar comonomers, DMT and BD, and the nonpolar PDMS. The molecular structure and composition of the copolymers were determined by ¹H‐NMR spectroscopy, whereas the effectiveness of the incorporation of α,ω‐dihydroxy‐(EO‐PDMS‐EO) into the copolymer chains was verified by chloroform extraction. The effects of the structure and composition of the copolymers on the melting temperatures and the degree of crystallinity, as well as on the thermal degradation stability and some rheological properties, were studied. It was demonstrated that the degree of crystallinity, the melting and crystallization temperatures of the copolymers increased with increasing mass fraction of the PBT segments. The thermal stability of the copolymers was lower than that of PBT homopolymer, because of the presence of thermoliable ether bonds in the soft segments. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis of ω‐pyrenyl‐functionalized poly(1,3‐cyclohexadiene)

ω‐Pyrenyl‐functionalized poly(1,3‐cyclohexadiene) (PCHD) was successfully synthesized by the postpolymerization reaction of poly(1,3‐cyclohexadienyl)lithium (PCHDLi) with 1‐chloromethylpyrene (ClMe‐PY). This postpolymerization reaction consisted of two competitive reactions: the addition reaction of the pyrenyl group, and a hydrogen abstraction reaction (lithiation) as a side reaction. The degree of nucleophilicity of PCHDLi was a very important factor for suppression of the side reaction, and the PCHDLi/amine system, which has high nucleophilicity, produced high ω‐pyrenyl‐functionalization for PCHD. The UV/vis and fluorescence spectra for ω‐pyrenyl‐functionalized PCHD were bathochromically shifted, relative to that of pyrene. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and properties of block and graft waterborne polyurethane modified with α,ω‐bis(3‐(1‐methoxy‐2‐hydroxypropoxy)propyl)polydimethylsiloxane and α‐N,N‐dihydroxyethylaminopropyl‐ω‐butylpolydimethylsiloxane

In this study, α,ω‐bis(3‐(1‐methoxy‐2‐hydroxypropoxy)propyl)polydimethylsiloxane and α‐N,N‐dihydroxyethylaminopropyl‐ω‐butylpolydimethylsiloxane were used to prepare block and graft waterborne polyureathane–polysiloxane copolymer dispersions. α,ω‐bis(3‐(1‐methoxy‐2‐hydroxypropoxy)propyl)polydimethylsiloxane was synthesized by hydrosilylation, methoxylation and equilibrium reactions; α‐N,N‐dihydroxyethylaminopropyl‐ω‐butylpolydimethylsiloxane was synthesized via hydroxyl protection, alkylation, anionic ring‐opening polymerization, hydrosilylation, and deprotection. Block and graft waterborne polyurethane–polysiloxane copolymer dispersions were prepared by the reaction of poly(propylene glycol) (PPG), toluene diisocyanate (TDI), 2,2‐dimethylol propionic acid (DMPA), 1,4‐butanediol (BDO), α,ω‐bis(3‐(1‐methoxy‐2‐hydroxypropoxy)propyl)polydimethylsiloxane, and α‐N,N‐dihydroxy‐ethylaminopropyl‐ω‐butylpolydimethylsiloxane. The water absorption of block and graft waterborne polyurethane–polysiloxane copolymer films decreased from 163.9 to 40.2% and 17.3%, respectively, when percent of polysiloxane (w/w) increased from 0 to 5%, and the tensile strength of the block waterborne polyurethane–polysiloxane copolymer films decreased while the tensile strength of graft waterborne polyurethane–polysiloxane copolymer films increased with increase of percent of polysiloxane. For graft waterborne polyurethane–polysiloxane films, the tensile strength would decrease when percent of polysiloxane was more than 3%. POLYM. ENG. SCI., 54:805–811, 2014. © 2013 Society of Plastics Engineers     

Temperature influence on the behavior of polysulfone‐b‐poly(alkylene oxide)‐b‐poly(dimethylsiloxane) triblock copolymers in a selective solvent

Triblock copolymers containing polysulfone, poly(alkylene oxide), and poly(dimethylsiloxane) segments were obtained by addition of preformed α,ω‐bis(hydrogensilyl) poly(dimethylsiloxane) oligomers to alyl end‐capped poly(alkylene oxide)‐b‐polysulfone. Viscometric and UV absorption measurements were carried out in dilute 1,2‐dichlorethane solutions, in the temperature range of 20–75°C. The specific interactions exhibited by the block copolymers in a selective solvent are influenced by the copolymer composition and temperature. The results point to a conformational transition phenomenon, located around 55°C, which is attributed to the transition from a segregated to a pseudo‐Gaussian conformation through a compressed‐segregated conformation. POLYM. ENG. SCI., 57:114–118, 2017. © 2016 Society of Plastics Engineers     

Synthesis and characterization of poly(ϵ‐caprolactone)–poly(L‐lactide) diblock copolymers with an organic amino calcium catalyst

The quasiliving characteristics of the ring‐opening polymerization of ?‐caprolactone (CL) catalyzed by an organic amino calcium were demonstrated. Taking advantage of this feature, we synthesized a series of poly(?‐caprolactone) (PCL)–poly(L ‐lactide) (PLA) diblock copolymers with the sequential addition of the monomers CL and L ‐lactide. The block structure was confirmed by ¹H‐NMR, ¹³C‐NMR, and gel permeation chromatography analysis. The crystalline structure of the copolymers was investigated by differential scanning calorimetry and wide‐angle X‐ray diffraction analysis. When the molecular weight of the PLA block was high enough, phase separation took place in the block copolymer to form PCL and PLA domains, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2654–2660, 2006     

One‐step synthesis of bis‐macromonomers of poly(1,3‐dioxolane) catalyzed by Maghnite‐H+

Telechelic poly(1,3‐dioxolane) (PDXL) bis‐macromonomers bearing methyl methacrylate end groups were prepared by cationic ring‐opening polymerization of 1,3‐dioxolane (DXL), in the presence of methacrylic anhydride, catalyzed by Maghnite‐H⁺ (Mag‐H⁺), in bulk and in solution. Maghnite is a montmorillonite sheet silicate clay, which exchanged with protons to produce Mag‐H⁺. The influence of the amount of Mag‐H⁺, monomer (DXL), and methacrylic anhydride on monomer conversion was studied. The polymerization yield and the molecular weight of α,ω‐bis‐unsaturated PDXLs prepared depend on the amount of Mag‐H⁺ used and the reaction time. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Synthesis and characterization of poly(methylphenylsilylene)–poly(ethylene oxide) and poly(methylphenylsilylene)–polyisoprene multiblock copolymers

Multiblock copolymers were synthesized through condensation reactions of end‐groups of α,ω‐dichloro‐poly(methylphenylsilylene) with hydroxyl end‐groups of poly(ethylene glycol) or the chain‐ends of ‘living’ polyisoprenyl disodium. Optimum conditions have been sought through kinetic studies and by investigation of model reactions. The overall molecular weight distribution of poly(methylphenylsilylene)‐block‐poly(ethylene oxide) is characterized in terms of Flory's theory of condensation reactions, while the limiting step in the reaction is tentatively attributed to the formation of aggregates. © 2001 Society of Chemical Industry     

Comb‐type methylsiloxane copolymers with diorganosilylene fragments as a lateral group

The catalytic dehydrocondensation reaction of α,ω‐bis(trimethylsiloxy)methylhydridesiloxane and of α,ω‐bis(trimethylsiloxy)methylhydridesiloxane‐dimethylsiloxane with α‐hydroxy‐ω‐trimethylsiloxydiorganosilylenes, in the presence of anhydrous caustic potassium, at 1:35 and 1:33 ratio of initial compounds has been investigated and polyorganosiloxanes with rigid polydiorganosilylenes fragment in the side chain, completely soluble in organic solvents, have been obtained. The catalytic dehydrocondensation reaction order, activation energies, and rate constants have been determined. The synthesized copolymers were characterized by thermogravimetric, gel permeation chromatographic, differential scanning calorimetric, and wide‐angle X‐ray analyses. It was shown that during modification of α,ω‐bis(trimethylsiloxy)methylhydridesiloxane‐dimethylsiloxane with α‐hydroxy‐ω‐trimethylsiloxydiorganosilylenes in synthesized block‐copolymers, microdomain structure (phase incompatibility) was observed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2161–2167, 2007     

Poly(hydroxyether of bisphenol A) ‐alt‐polydimethylsiloxane: a novel thermally crosslinkable alternating block copolymer

BACKGROUND: An important strategy for making polymer materials with combined properties is to prepare block copolymers consisting of well‐defined blocks via facile approaches. RESULTS: Poly(hydroxyether of bisphenol A)‐block‐polydimethylsiloxane alternating block copolymers (PH‐alt‐PDMS) were synthesized via Mannich polycondensation involving phenolic hydroxyl‐terminated poly(hydroxyether of bisphenol A), diaminopropyl‐terminated polydimethylsiloxane and formaldehyde. The polymerization was carried out via the formation of benzoxazine ring linkages between poly(hydroxyether of bisphenol A) and polydimethylsiloxane blocks. Differential scanning calorimetry and small‐angle X‐ray scattering show that the alternating block copolymers are microphase‐separated. Compared to poly(hydroxyether of bisphenol A), the copolymers displayed enhanced surface hydrophobicity (dewettability). In addition, subsequent crosslinking can occur upon heating the copolymers to elevated temperatures owing to the existence of benzoxazine linkages in the microdomains of hard segments. CONCLUSION: PH‐alt‐PDMS alternating block copolymers were successfully obtained. The subsequent self‐crosslinking of the PH‐alt‐PDMS alternating block copolymers could lead to these polymer materials having potential applications. Copyright © 2008 Society of Chemical Industry     

Synthesis,characterization and biocompatibility of novel biodegradable poly[((R)‐3‐hydroxybutyrate)‐block‐(D,L‐lactide)‐block‐(ε‐caprolactone)] triblock copolymers

BACKGROUND: Biodegradable block copolymers have attracted particular attention in both fundamental and applied research because of their unique chain architecture, biodegradability and biocompatibility. Hence, biodegradable poly[((R )‐3 ‐hydroxybutyrate)‐block‐(D ,L ‐lactide)‐block‐(ε‐caprolactone)] (PHB‐PLA‐PCL) triblock copolymers were synthesized, characterized and evaluated for their biocompatibility. RESULTS: The results from nuclear magnetic resonance spectroscopy, gel permeation chromatography and thermogravimetric analysis showed that the novel triblock copolymers were successfully synthesized. Differential scanning calorimetry and wide‐angle X‐ray diffraction showed that the crystallinity of PHB in the copolymers decreased compared with methyl‐PHB (LMPHB) oligomer precursor. Blood compatibility experiments showed that the blood coagulation time became longer accompanied by a reduced number of platelets adhering to films of the copolymers with decreasing PHB content in the triblocks. Murine osteoblast MC3T3‐E1 cells cultured on the triblock copolymer films spread and proliferated significantly better compared with their growth on homopolymers of PHB, PLA and PCL, respectively. CONCLUSION: For the first time, PHB‐PLA‐PCL triblock copolymers were synthesized using low molecular weight LMPHB oligomer as the macroinitiator through ring‐opening polymerization with D ,L ‐lactide and ε‐caprolactone. The triblock copolymers exhibited flexible properties with good biocompatibility; they could be developed into promising biomedical materials for in vivo applications. Copyright © 2008 Society of Chemical Industry     

Preparation of 1,3‐Diazido‐2‐Nitro‐2‐Azapropane from Urea

An alternative method to prepare 1,3‐diazido‐2‐nitro‐2‐azapropane (DANP), a promising liquid component for high‐energy condensed systems, is suggested and involves the following stages: (i) nitration of urea, (ii) condensation of the nitration product with formaldehyde, (iii) acylation (chlorination) of 1,3‐dihydroxy‐2‐nitro‐2‐azapropane, (iv) chlorination of 1,3‐diacetoxy‐2‐nitro‐2‐azapropane, and (v) azidation of the dichloro derivative to DANP. This synthesis method is selective and enables isolation of 1,3‐diazido‐2‐nitrazapropane devoid of impurities.     

Conformations of polysulfone‐block‐polydimethylsiloxane chains in solution and in the solid state

Polysulfone block copolymers containing polydimethylsiloxane segments were obtained in solution by the condensation reaction of chloro‐terminated polysulfone oligomers and α,ω‐dihydrogensilyl‐polydimethylsiloxane. The conformations of the copolymer chains were investigated both in solution and in the solid state. Viscometric and UV absorption measurements were carried out in dilute dichloroethane solutions over a wide region of concentrations, in the temperature range 20–75 °C. The results point to a conformational transition phenomenon, located at around 55 °C, which is attributed to the transition from a segregated to a pseudo‐Gaussian conformation through a compressed‐segregated conformation. Copyright © 2004 Society of Chemical Industry     

Synthesis and characterization of novel urethane‐siloxane copolymers with a high content of PCL‐PDMS‐PCL segments

Novel polyurethane copolymers derived from 4,4′‐methylenediphenyl diisocyanate (MDI), 1,4‐butanediol (BD) and α,ω‐dihydroxy‐[poly(caprolactone)‐poly (dimethylsiloxane)‐poly(caprolactone)] (α,ω‐dihydroxy‐(PCL‐PDMS‐PCL); = 6100 g mol^?1) were synthesized by a two‐step polyaddition reaction in solution. In the synthesis of the polyurethanes, the PCL blocks served as a compatibilizer between the nonpolar PDMS blocks and the polar comonomers, MDI and BD. The synthesis of thermoplastic polyurethanes (TPU) with high soft segment contents was optimized in terms of the concentrations of the reactants, the molar ratio of the NCO/OH groups, and the time and temperature of the polyaddition reaction. The structure, composition, and hard MDI/BD segment length of the synthesized polyurethane copolymers were determined by ¹H, ¹³C‐NMR, and two‐dimensional correlation (COSY, HSQC, and HMBC) spectroscopy, while the hydrogen bonding interactions in the copolymers were analyzed by FT‐IR spectroscopy. The influence of the reaction conditions on the structure, molecular weight, thermal, and some physical properties was studied at constant composition of the reaction mixture. A change in the molar ratio of the NCO/OH groups and the reaction conditions modified not only the molecular weight of the synthesized polyurethanes, but also the microstructure and therefore the thermal and physical properties of the copolymers. It was demonstrated that only PCL segments with high soft segment contents crystallize, thereby showing spherulitic morphology. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and surface properties of polydimethylsiloxane‐based block copolymers: poly[dimethylsiloxane‐block‐ (ethyl methacrylate)] and poly[dimethylsiloxane‐block‐(hydroxyethyl methacrylate)]

A polydimethylsiloxane (PDMS) macroazoinitiator was synthesized from bis(hydroxyalkyl)‐terminated PDMS and 4,4′‐azobis‐4‐cyanopentanoic acid by a condensation reaction. The bifunctional macroinitiator was used for the block copolymerization of ethyl methacrylate (EMA) and 2‐(trimethylsilyloxy)ethyl methacrylate (TMSHEMA) monomers. The poly(DMS‐block‐EMA) and poly(DMS‐block‐TMSHEMA) copolymers thus obtained were characterized using Fourier transform infrared and ¹H NMR spectroscopy and differential scanning calorimetry. After the deprotection of trimethylsilyl groups, poly(DMS‐block‐HEMA) and poly(DMS‐block‐EMA) copolymer film surfaces were analysed using scanning electron microscopy and X‐ray photoelectron spectroscopy. The effects of the PDMS concentration in the copolymers on both air and glass sides of films were examined. The PDMS segments oriented and moved to the glass side in poly(DMS‐block‐EMA) copolymer film while orientation to the air side became evident with increasing DMS content in poly(DMS‐block‐HEMA) copolymer film. The block copolymerization technique described here is a versatile and economic method and is also applicable to a wide range of monomers. The copolymers obtained have phase‐separated morphologies and the effects of DMS segments on copolymer film surfaces are different at the glass and air sides. Copyright © 2010 Society of Chemical Industry     

Poly(α-methylstyrene)–poly(dimethylsiloxane) block copolymers

Block copolymers were synthesized by the condensation of dihydroxyl-terminated poly-(α-methylstyrene) oligomers and bisdimethylamino-terminated poly(dimethylsiloxane) oligomers. Manipulation of block molecular weight produced copolymers ranging in composition from 21% to 73% poly(dimethylsiloxane). Compression moldablity was found to be good. Physical properties were dependent upon siloxane content, varying from high modulus, low elongation to low modulus, high elongation materials. High siloxane-content compositions exhibited elastomeric properties due to the two-phase morphology of these systems. Glass transition temperatures were observed as low as ?120°C for the poly(dimethylsiloxane) block and as high as + 140°C for the poly(α-methylstyrene) block. Even higher poly(α-methylstyrene) transition temperatures may be possible by using higher molecular weight oligomers.