Crosslinked polydiacetylene and its two- and three-component interpenetrating polymer networks (IPNs)

The synthesis of crosslinked polydiacetylene [poly4ECMU (a polydiacetylene with ethoxy carbonyl methylene urethane substitution): where R = ? (CH₂)₄OCONHCH₂COOCH₂CH₃] was carried out utilizing its polar and flexible substituent groups. Polydiacetylene was crosslinked by the formation of allophanate linkages utilizing urethane groups in the substituent groups of the polydiacetylene. Two-component IPNs of polydiacetylene [poly4BCMU (a polydiacetylene with butoxy carbonyl methylene urethane substitution): where R = ? (CH₂)₄OCONHCH₂COO(CH₂)₃CH₃] and an epoxy resin (diglycidyl ether of Bisphenol A) were synthesized. Two-component IPNs of poly4ECMU with the above epoxy resin were also synthesized. For the first time, two-component stiff-backbone IPNs of two different kinds of polydiacetylene (poly4BCMU and polyECMU) and a three-component IPN of poly4BCMU, poly4ECMU, and the epoxy resin were synthesized. IPNs with fewer allophanate linkages were also made in order to examine morphological differences between them. The glass transition behavior of these networks was studied using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) by means of a Rheovibron.     

SYNTHESIS AND CHARACTERIZATION OF POLYDIMETHYLSILOXANE/POLYSTYRENE SEMIINTERPENETRATING POLYMER NETWORKS

The synthesis of pseudo- and semi-interpenetrating polymer networks (IPNs) based on poly-dimethylsiloxane (PDMS) and polystyrene (PS) is described. IPNs were obtained by simultaneous and in situsequential synthesis procedure. The preliminary studies on IPNs properties such as transition temperature,microphase separation and mechanical behaviors have been carried out by using differential scanningcalorimetry (DSC) and scanning electron microscopy (SEM). The experimental evidence clearly showed thatsemi-IPNs obtained by sequential synthesis procedure have higher interpenetrating extent than pseudo-IPNssynthesized by simultaneous procedure. Over the full composition, the PDMS/PS IPNs are immiscible. Thepseudo-IPNs microphase separation can be greatly subdued through the formation of grafting bonds betweentwo networks as well as the kinetic rate-matching of the individual network crosslinking.     

New interpenetrating polymer networks based on uralkyd/poly(glycidyl methacrylate)

Semi- and full-interpenetrating polymer networks (IPNs) based on uralkyd resin (UA)/poly(glycidyl methacrylate) were synthesized in the laboratory by the sequential technique. Infrared spectra of the homopolymers and the IPNs were studied. A study of the mechanical properties viz. tensile strength and elongation percentage was carried out. The apparent densities of the homopolymers and their IPNs were determined and compared. Glass transition studies of the IPNs were conducted with the aid of differential scanning calorimetry (DSC). Phase morphology of the IPNs was observed using scanning electron microscopy (SEM). DSC results revealed a single glass transition temperature (T_g) for both the semi- as well as the full-IPNs suggesting good interpenetration in them. The SEM micrographs as well as the IR-spectra gave an indication that apart form the interpenetration phenomena, grafting reaction between the -NCO groups of UA and the epoxy group of glycidyl methacrylate might have occurred to some extent.     

The Effect of Synthesis Method on Three-component IPNs Morphology and Property

Three-component IPNs were synthesized from polyurethane/poly (methyl acrylate aminoethyl methacrylate)/epoxy resin [PU/P(MADMA)/EP] by simultaneous synthesis interpenetrating polymer networks method(SINs) and sequential synthesis interpenetrating polymer networks method (STPNs). Comparing the effect of the two synthesis methods on the morphology and mechanical properties of three-component IPNs, it was found that the compatibility of three-component IPNs depends on the component ratios and interpenetrating formation , the different synthesis methods make the entanglement and interpenetrating between networks changed. The tensile strength of SIPNs is bigger than that of SINs, while the elongation at break of SINs is bigger than that of SIPNs. It is feasible to use stepwise staining method to observe the morphology change.     

Synthesis and Characterization of Polymeric Acid‐Doped Polyaniline Interpenetrating Polymer Networks

Polyaniline (PANI)/poly(2‐acrylamido‐2‐methylpropane sulfonic acid) (PAMPS) semi‐interpenetrating network polymers (semi‐IPNs) were prepared using the simultaneous method. The formation and properties of the interpenetrating PANI/PAMPS semi‐IPNs were investigated using Fourier transform infrared spectroscopy, X‐ray diffraction, solid‐state ¹³C‐NMR, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The interaction of PAMPS with PANI as a polymeric acid dopant was also investigated. These semi‐IPNs had a different microstructure compared to that of pure PANI. Packing structures and several decomposition steps were ordered for each semi‐IPN, while pure PANI exhibits a single amorphous peak and one decomposition step. The NMR spectra show that these peaks broaden and shifted downfield in the semi‐IPNs. A thermal reaction between PANI and PAMPS was observed using DSC and TGA, and the data from the two techniques are in agreement.     

Laccase‐catalyzed polymerization of lignocatechol and affinity on proteins of resulting polymers

For the synthesis of a new biologically functional polymer from a natural resource by an environment‐friendly method, the laccase‐catalyzed polymerization of a lignin‐based macromonomer, lignocatechol, was carried out for the first time in ethanol–phosphate buffer solvent system to give crosslinked polymers in good yields. Lignocatechol was prepared by the phase separation system of lignin and catechol in aqueous sulfuric acid. The copolymerization was also performed with urushiol to afford the corresponding copolymers in high yields. The polymerization mechanism was estimated by the IR and pyrolysis GC‐MS measurements, suggesting that the polymerization proceeded mainly at the catechol ring through a quinone radical intermediate. The thermal properties were measured by the DSC, TG, and TMA analyses, indicating that the polymers had high thermal stabilities because of the crosslinked structures. In addition, it was found that the resulting polymers had the affinity of bovine serum albumin (BSA) and glucoamylase. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 824–832, 2009     

Electrically conductive pseudo IPNs of linear poly(carbonate-urethane) and crosslinked polychloroprene

A number of pseudo IPNs of poly(carbonate-urethane) (PCU) and crosslinked polychloroprene (CR) have been synthesized and characterized. The single phase morphology of these novel pseudo IPNs has been confirmed by DSC measurements and electron microscopy. The room temperature electrical conductives of homopolymers and pseudo IPNs have been investigated for both undoped and iodine-doped samples. © 1994 John Wiley & Sons, Inc.     

不饱和聚酯／聚氨酯互穿网络聚合物的合成

以醋酸酐封端的不饱和聚酯（ＦＵＰＲ）与交联聚氨酯预聚物制备了具有互穿聚合物网络（ＩＰＮ）的不饱和聚酯／聚氨酯，通过红外，ＤＳＣ和扫描电镜等分析了ＦＵＰＲ／ＰＵＩＰＮ网络形成的动力学，微相分离行为及力学性能，结果表明，当ＦＵＰＲ／ＰＵ达到某一比值时，产生网络互穿效应，可改善聚氨酯的刚性，提高不饱和聚酯的抗冲性。     

Dual temperature‐ and pH‐sensitive hydrogels from interpenetrating networks and copolymerization of N‐isopropylacrylamide and sodium acrylate

Hydrogels responsive to both temperature and pH have been synthesized in the forms of sequential interpenetrating networks (IPNs) of N‐isopropylacrylamide (NIPAAm) and sodium acrylate (SA) and compared with the crosslinked random copolymers of N‐isopropylacrylamide and SA. Whereas the stimuli‐sensitive behaviors of copolymer hydrogels were strongly dependent on the ionic SA contents, the IPN hydrogels exhibited independent swelling and thermal behaviors of each network component. The sequences and media in the synthesis of IPNs influenced the swelling capacities of the IPNs, but not the temperature or pH ranges at which the swelling changes occurred. In IPNs, a more expanded primary gel network during the synthesis of the secondary network contributed to the better swelling of the final IPNs. Both the swelling and thermal behaviors of the IPNs suggest that poly(N‐isopropylacrylamide) and poly(sodium acrylate) are phase separated regardless of their synthesis conditions. The presence of the poly(sodium acrylate) network did not influence the temperature or the extent of phase transition of the poly(N‐isopropylacrylamide) network in the IPNs, but did improve the thermal stability of the IPNs. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3293–3301, 2004     

脂肪族聚碳酸酯型聚氨酯/聚甲基丙烯酸甲酯互穿网络聚合物的研究

用同步法合成了聚碳酸亚丙酯聚氨酶／聚甲基丙烯酸甲醇互穿网络聚合物（PPCPU／PMMA，IPN），调节IPN中两组分配比制备出多种高聚物共混物。用DSC、TEM对IPN的研究结果表明．PPCPU／PMMA之IPN的两组分是互不相容的。同时对各种组成比的IPN材料进行力学性能测试，并用SEM对断面进行了观察，发现IPN的密度大于相应体系体积加和值。     

聚环氧氯丙烷聚氨酯／聚甲基丙烯酸甲酯互穿网络聚合物的相容性与力学性能

用同步法合成了聚环氧氯丙烷聚氨酯／聚甲基丙烯酸甲酯互穿网络聚合物［ＰＵ（ＰＥＣＨ）／ＰＭＭＡＩＰＮ］，调节ＩＰＮ中两组分组成比制备出由完全弹性体、增强弹性体、增韧塑料到脆性塑料多种高聚物合金材料．用ＤＳＣ、动态力学谱、ＴＥＭ对ＩＰＮ的研究结果表明，ＰＵ（ＰＥＣＨ）／ＰＭＭＡＩＰＮ的两组分是完全相容的；同时对各种组成比的ＩＰＮ材料进行力学性能测试，用相容性ＩＰＮ中互穿、缠结结构解释其力学行为，并用ＳＥＭ对断面形貌进行了观察解释．     

Thermal transitions of benzene in copolymers and interpenetrating polymer networks based on hydrophilic and hydrophobic components: Experimental evidence of hydrophobic interaction

Thermal transitions of benzene in a hydrophobic polymer network have been explained by us in terms of the phase diagram of the polymer‐solvent system. In this work, we executed a similar study on copolymers and interpenetrating polymer networks (IPNs) with controllable hydrophilic/hydrophobic ratios. Copolymers and IPNs were swollen with different amounts of benzene and subjected to cooling and heating scans with differential scanning calorimetry (DSC). Synthesis of the IPNs was carried out in such a way that phase separation appeared, and three qualitatively different types of DSC thermograms were identified depending on the benzene content of IPN. Thermal transitions of benzene in the hydrophilic/hydrophobic copolymers can also be explained as a consequence of the phase diagram of the system, but an increase in the glass‐transition temperature of the system can be correlated with the interactions among the hydrophilic groups of the copolymer. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1713–1721, 2003     

Poly(Ether sulfone)s made from 4,4′-dihydroxystilbene and 4,4′-difluorodiphenylsulfone: Synthesis,crosslinking, and epoxidation with hydrogen peroxide

High molecular weight polymers from trans-4,4′-dihydroxystilbene, bisphenols, and 4,4′-difluorodiphenylsulfone were synthesized by a nucleophilic displacement reaction using DMAc as solvent in the presence of potassium carbonate. Characterization and crosslinking studies of these polymers were carried out by DSC, TGA, TMA, x-ray diffraction, and solution and solid NMR. It was found that all polymers can be crosslinked to some extent on heating to 350°C. We also studied the epoxidation of these polymers with hydrogen peroxide in the presence of methyltrioctylammonium tetrakis (diperoxotungsto) phosphate (3—) as the catalyst in a biphasic system. The epoxidized polymers are thermally cross-linkable. Very efficient crosslinking was obtained by heating the epoxidized polymers at 350°C under nitrogen. © 1995 John Wiley & Sons, Inc.     

Synthesis, characterization and thermoreversible behaviours of poly(dimethyl siloxane)/poly(N-isopropyl acrylamide) semi-interpenetrating networks

Simultaneous and sequential poly(N-isopropyl acrylamide) (PNIPAAm)/poly(dimethyl siloxane) (PDMS) semi-interpenetrating polymer networks (IPNs) with different linear PDMS contents were prepared by free radical polymerization method. Their phase morphologies have been characterized by FTIR, DSC and SEM. The simultaneous semi-IPNs exhibited phase transition temperatures (T_pt) shifted higher temperature from glass transition temperatures (T_g) of their respective homopolymers, suggesting a heterophase morphology and only physical entanglement between the PNIPAAm network and linear PDMS with high molecular weight (Mn≈9000 g/mol). For sequential semi-IPNs, the shift of T_pts towards lower temperature suggested that the chemical interaction between the constituents of the IPNs increased with increasing PDMS content in the network. In addition, these semi-IPNs were characterized for their thermo-sensitive behaviour by equilibrium swelling studies. The results showed that incorporation of hydrophobic PDMS polymer into the thermo- and pH-sensitive PNIPAAm and P(NIPAAm-co-IA) (itaconic acid) hydrogels by semi-IPN formation decreased swelling degrees of IPNs without affecting their LCSTs whereas addition of acrylated PDMS (Tegomer V-Si 2250) as crosslinker instead of N,N^′-methylenebisacrylamide (BIS) into the structures of these hydrogels changed their LCSTs along with their swelling degrees.     

Hybrid inorganic/organic interpenetrating polymer networks based on zeolite 13x and polystyrene

A hybrid inorganic/organic interpenetrating polymer network (IPN) of a three-dimensional network structure zeolite crystal (13X, powder) and crosslinked or linear polystyrene (PS) was prepared and characterized by differential scanning calorimetry (DSC), solid-state¹³C-NMR, and scanning electron microscopy (SEM). The size and shape of the crystalline zeolite particles were revealed on SEM micrographs in both the pure zeolite and the IPNs. Solubility tests and the results of DSC with solid-state ¹³C-NMR confirm that some organic PS chains are incorporated within the internal three-dimensional channels of the zeolite particles. We speculate that the internal PS chains may adopt an extended “one-dimensional” conformation and exhibit no bulk polymer glass transition. These novel hybrid inorganic/organic IPNs are a new kind of IPN structure. © 1995 John Wiley & Sons, Inc.     

Poly(ethylene oxide)/poly(methyl methacrylate) (semi-)interpenetrating polymer networks: Synthesis and phase diagrams

Interpenetrating polymer networks (IPNs) of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) were prepared by simultaneous network formation. The PEO network was produced by acid-catlayzed self-condensation of α,ω-bis(triethoxysilane)-terminated PEO in the presence of small amounts of water. The PMMA network was formed by free radical polymerization of MAA in the presence of divinylbenzene as crosslinker. The reaction conditions were adjusted to obtain similar crosslinking kinetics for both reactions. An attempt was made to construct a phase diagram of the IPNs by measuring the composition of the IPNs at the moment of the appearance of the phase separation, as indicated by the onset of turbidity. This composition could be determined because the siloxane crosslinks of the PEO network could be hydrolyzed in aqueous NaOH with the formation of linear, soluble PEO chains. The phase diagram was compared with phase diagrams of blends of linear polymers and of semi-IPNs (crosslinked PMMA and linear PEO), obtained under similar conditions, i.e. polymerization of MMA in the presence of varying amounts of PEO. It was observed that the form of the phase diagrams of the linear polymers is similar to that of the IPNs, but is quite different from that of the semi-IPNs. Thus, homogeneous transparent materials containing up to 60% of PEO could be prepared in the blends and the IPNs, but in the semi-IPNs, phase separation occurred with PEO contents as low as 10%.     

Stereoselective synthesis of benzofulvenes via a palladium-catalyzed cyclization of 1,3-dienes derived from Morita–Baylis–Hillman adducts

A facile synthesis of benzofulvenes was carried out starting from the Morita–Baylis–Hillman adducts of 2-bromobenzaldehyde. The synthesis was carried out via the sequential bromination, Wittig reaction with aldehyde, and Pd-catalyzed intramolecular Mizoroki–Heck reaction. The stereochemistry of benzofulvenes was dependent on the reaction condition, especially on the kinds of base and reaction time, and the substituent of starting materials.     

Synthesis,characterization, and mechanical properties of PMMA/poly(aromatic/aliphatic siloxane) semi-interpenetrating polymer networks

Semi-interpenetrating polymer networks (IPNs) composed of poly(methyl methacrylate) (PMMA) and aromatic/aliphatic siloxanes have been made via sequential and simultaneous polymerizations. As the percentage of aliphatic siloxane increases, flexibility and, in general, toughness of the IPNs increases and clarity is reduced. This loss in clarity is due to the mismatch of refractive indices (1.49 form PMMA vs. 1.43 for aliphatic siloxane). PMMA is quite transparent. On the other hand, in making aromatic siloxane/PMMA IPNs clarity is retained as aromatic siloxane is increased due to better matching refractive index (1.49 for PMMA and −1.49 for poly(diphenyl siloxane)). Gel permeation chromatography (GPC) indicates slightly crosslinked IPNs with the THF soluble portions having number-average molecular weight, M¯_n, of 10⁵–10⁶. NMRs of IPNs essentially show peaks for the components, PMMA and the siloxane, which make up the respective IPNs. ²⁹Si-NMRs indicate cross-linking and grafting. Mechanical properties show increased toughness of IPNs versus PMMA as percentage of siloxane and crosslinker increases, but with a corresponding loss in tensile strength. © 1996 John Wiley & Sons, Inc.     

Epoxy-poly(2-ethylhexyl acrylate) interpenetrating polymer networks morphology and mechanical and thermal properties

Full and semi-IPNs of Poly(2-ethylhexyl acrylate), PEHA & crosslinked epoxy homopolymer were prepared and characterized by measurements of mechanical, thermal and morphological properties. Aromatic polyamine adducts and ethylene glycol dimethacrylate were used as the cross-linker for epoxy and comonomer/cross-linker for 2-ethyl hexyl acrylate monomer. Effects of changes of blend ratio on the properties were examined. Semi-IPNs were characterized by higher tensile strength and modulus than the corresponding full IPNs. Both semi- and full IPNs were characterized by broadening of transitions in their respective DSC curves while the weight retention in the thermal decomposition of the IPNs and pseudo-IPNs was higher than the epoxy homopolymer network. Phase separated rubber domains of various sizes are presumed to be responsible for the increased toughness of poly(2-ethyl hexyl acrylate)-modified epoxy which is substantiated by SEM micrographs.     

Influence of polymer composition on the thermal characteristics of sulfonated EPDM ionomers

Detailed thermal characterization of sulfo-EPDM ionomers was carried out. The endotherms observed via differential scanning calorimetry (DSC) and multiple inflections observed via thermal mechanical analysis (TMA) are speculated to be due to associated ionic species in the polymers. A large time dependence of the DSC endotherm was observed, suggesting substantial variations in the nature of the ionic species over this period. The influence of ionomer composition on thermal characteristics was probed with whole polymers and polymer fractions. In general, trends in the DSC and TMA data paralleled those expected on the basis of the anticipated effect of polymer sulfonation level, molecular weight, and counterion type on the strength of the physical crosslinking of these polymers. Both the DSC endotherms and the TMA inflection regions are rationalized in terms of a previously developed ionic-bond exchange model.