Synthesis of a new EPM-polystyrene graft terpolymer

Summary An EPDM graft terpolymer was prepared using the macromer polystyryldicyclopentadiene (PSt-DCp). Terpolymerization of PSt-DCp with ethylene and propylene led to a new material containing five branches per chain. The terpolymer was characterized by GPC, osmometric measurements, and NMR spectroscopy.     

Biodegradable poly(L‐lactide) and polycaprolactone block copolymer networks

New biodegradable block copolymer networks were synthesized from methacrylate‐terminated poly(L ‐lactide) (mLA) and polycaprolactone (mCL) macromers. This allowed the realization of a series of materials in which the macromer ratio can be used to tailor the physical and mechanical properties of the materials. The synthesis of the macromers was characterized using Fourier transform infrared (FTIR) spectroscopy and ¹H NMR spectroscopy. Poly(mCL) and poly(mLA) networks were prepared by photopolymerization of the macromers, and copolymers were also prepared from the two macromers in various proportions. The phase microstructure of the new systems and the network architecture were investigated using differential scanning calorimetry, FTIR spectroscopy, dynamic mechanical analysis and thermogravimetry studies. Copyright © 2010 Society of Chemical Industry     

Effect of the lateral substituent on the mesomorphic behavior of side-chain liquid-crystalline polymers containing a Schiff base ester

New polymerizable macromers containing a Schiff base ester linkage have been synthesized. These macromers were used to synthesize side-chain liquid-crystalline polymers (SCLCPs) by radical polymerization. The chemical structures of the macromers and polymers were characterized by spectroscopic techniques (FTIR, ¹H NMR, and ¹³C NMR). The mesomorphic properties of the macromers as well as the polymers were studied by polarized optical microscopy (POM) and differential scanning calorimetry (DSC) and confirmed by powder X-ray diffraction (PXRD). POM and DSC studies revealed that all of the macromers and polymers showed liquid crystal behavior, with their nematic phases occurring in different mesophase ranges. The macromer without a lateral unit in the mesogen (M1) showed a thermal transition at a relatively high temperature (181.4 °C), whereas the macromer with a lateral unit in the mesogen (M2) showed a thermal transition at a relatively low temperature (101.8 °C). The SCLCP from macromer M1 (HPM1) also showed a comparatively high-temperature thermal transition compared to that of the polymer from macromer M2 (HPM2). The thermal properties of the polymers were studied by thermogravimetric analysis (TGA). The polymer from the macromer with a lateral unit in the mesogen (M2) showed higher thermal stability than the polymer from the macromer without a lateral unit (M1).     

Synthesis and characterization of polyurethane hybrids: Influence of the polydimethylsiloxane linear chain and silsesquioxane cubic structure on the thermal and mechanical properties of polyurethane hybrids

The structural effects of polydimethylsiloxane (PDMS) or polyhedral oligosilsesquioxanes (POSSs) on the thermomechanical properties of polyurethane (PU) networks were studied. An ester–amine‐functionalized silsesquioxane and a PDMS macromer were synthesized, and the macromer (10 wt %) was crosslinked with the PU prepolymer to obtain PU networks. The synthesized macromers and hybrids were characterized with Fourier transform infrared, ¹H‐NMR, ¹³C‐NMR, and ²⁹Si‐NMR spectroscopy techniques. The influence of POSS cubes on the thermal and mechanical properties of the polymer network films was studied comparatively with the similarly functionalized PDMS linear chain via thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA) measurements. The degradation pattern of the POSS‐incorporated PU nanocomposites was almost the same as that of the PU network synthesized from the linear PDMS macromer. The differences in the char yields and activation energies of the hybrids reflected the enhancement of the thermal properties of the nanohybrids. The TGA and DSC curves of the macromers suggested that the thermal properties of the macromers not only depended on either the PDMS or POSS inorganic core but also depended on the organic peripheral attached to the inorganic core. The glass‐transition temperatures of the nanohybrids were higher than those of the linear‐PDMS‐incorporated hybrids. The storage modulus values increased 3‐fold upon the incorporation of POSS rigid groups into the PU hybrids in comparison with the flexible PDMS‐chain‐incorporated PU hybrids. The DMA measurements showed a long‐range rubbery plateau region for all the PU hybrids, with high storage modulus and tan δ values showing the structural homogeneity of the crosslinked networks. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Multiphase materials with lignin: 9. Effect of lignin content on interpenetrating polymer network properties

A series of lignin-based polyurethane/poly(methyl methacrylate) (LPU/PMMA) interpenetrating polymer networks (IPNs) were prepared by solvent casting in film form. While the LPU/PMMA ratio remained constant (1:1), the properties of the LPU were controlled by varying the composition of the hydroxypropyl lignin polyol via chain extension with propylene oxide. An increase in the lignin content of the polyol resulted in a decrease in the molecular weight between crosslinks (M_c) and change in the morphology of the LPU/PMMA composite. This effect resulted in the transition from a two-phase material to a single-phase material when the (true) lignin content of the composite rose above 25 wt%. As the lignin content increased, the strength properties of the composites increased. The dynamic mechanical, thermal and ultimate mechanical properties of the entire series of IPNs could be explained by dual phase continuity.     

Reactive and stimuli-responsive maleic anhydride containing macromers – multi-functional cross-linkers and building blocks for hydrogel fabrication

Macromers with functional groups that allow for chemical derivatization, polymerization reactions or impart specific physico-chemical properties are functional building blocks for polymeric systems used in different biomedical applications. With this motivation, a series of oligomeric macromers was synthesized by free radical polymerization of maleic anhydride (MA) with N-isopropylacrylamide (NiPAAm) and pentaerythritol diacrylate monostearate (PEDAS). This chemical design provides anhydride groups for effective reactivity of the macromers with amines and other nucleophiles, copolymerized NiPAAm for temperature responsiveness and lipophilic stearate domains for increased hydrogel stability. Macromers were synthesized with different MA co-monomer feeds and oligomeric molecules (Mn below 5000 Da) were obtained with MA contents between 7% and 27% as determined by titration. The fraction of chemically intact anhydrides was calculated to range from 75% to 80%. The ability of the macromers to cross-link di- or oligovalent amines as a function of MA content was investigated rheologically. It was also demonstrated that monovalent amines, e.g. aminofluorescein, could be grafted to the macromer chain utilizing only a fraction of the anhydride functionalities. The derivatized macromers could still participate in cross-linking reactions due to the remaining anhydrides. Temperature sensitivity was shown for aqueous solutions of macromers with fully dissociated anhydride groups. The solutions were additionally responsive to changes in calcium ion concentration and pH. Extracts from macromer cross-linked polyether hydrogels showed no toxicity on L929 fibroblasts.The macromers have perspective as biocompatible cross-linkers for hydrogel fabrication from various biomacromolecules with the opportunity to decorate the gels with monoamine molecules that alter the biological or physico-chemical properties.     

用於光学复合材料的紫外光固化莰烯衍生物改性环氧活性大分子单体及其聚合反应

高次球面方程变焦距组合镜头是一种高技术产品，它对用放这类产品的高聚物的性能提出了极为苛刻的要求。遵循分子设计的基本原则，我们进行了新型改性环氧树脂、羟烷基教烯不饱和衍生物，活性多官能交联共聚单体及铁盐的设计与合成，光敏体系的选配，聚合条件的优化及紫外光辐照下安息香乙酸与铁盐复合引发的游离基一阳离子开环共聚反应的研究，并对产物的相关性能进行了系统测定。实验结果表明：兼具软、硬段结构和环氧基、羟基、波基、芳环、醚基的不饱和环氧甲基丙烯酸酯，不仅在250urn，290一310urn有强吸收峰，且在363urn左右还有一个…     

Methacryl-terminated macromers by living polymerization as precursors of IPN polymer electrolytes

A new class of polymer electrolytes, based on the interpenetrating polymer network approach, was obtained starting from functionalised macromers, of poly-ether nature, in the presence of a lithium salt (LiBF₄, LiClO₄, LiCF₃SO₃) and propylene carbonate (PC) or tetraethyleneglycol dimethylether (TGME), as plasticizers.

The macromers were synthesised by living polymerisation employing a HI/I₂ system as the initiator. The macromer has a polymerisable end group, which can undergo radical polymerisation, attached to a monodisperse poly-vinylether, containing suitable ethylene oxide groups for ion coordination. Monomers and macromers were characterised by FTi.r., u.v.–vis, ¹H- and ¹³C-n.m.r.

Self-consistent and easily handled membranes were obtained as thin films by a dry procedure using u.v. radiation to polymerise and crosslink the network precursors, directly on suitable substrates, in the presence of the plasticizer and the lithium salt. The electrolytic membranes were studied by complex impedance and their thermal properties determined by differential scanning calorimetry analysis.

Ionic conductivities (σ) were measured for PC and TGME-based membranes at various plasticizer and salt contents as a function of T (60 to −20°C). LiClO₄/PC/PE electrolytes, with 3.8% (w/w) salt and 63% PC, have the highest σ (1.15×10⁻³ and 3.54×10⁻⁴ S cm⁻¹ at 20°C and −20°C, respectively). One order of magnitude lower conductivities are achieved with TGME; samples with 6% (w/w) LiClO₄ and 45% (w/w) TGME exhibit σ values of 2.7×10⁻⁴ and 2.45×10⁻⁵ S cm⁻¹ at 20°C and −20°C.     

Macromers by carbo-cationic polymerization

Summary An EPDM graft terpolymer was prepared using the macromer polyisobutenyldicyclopentadiene (PIB-DCp). Terpolymerization of PIB-DCp with ethylene and propylene led to a new material containing one branch per chain. The terpolymer was characterized by GPC which revealed a single, rather narrow peak in the chromatogram. Osmometric measurements indicated a Mn of 60,000, and the overall composition of the graft was determined by nmr spectrometry.     

Styrenation of triglyceride oils by macromonomer technique

A novel macromer technique is described for the styrenation of triglyceride oils. Triglyceride oil-based macromers were prepared via successive transesterification and condensation reactions. The macromers were styrenated at 100°C using benzoyl peroxide as an initiator. The styrenation led to improved film properties with semidrying oils. Homopolymerization of the macromonomers failed due to the stearic hindrance of the bulky oil moieties. The results obtained were also evaluated by considering the degree of unsaturation. Chemical Engineering Dept., 80628 Maslak — ISTANBUL Tel.: +90 212 285 6835 or 6836 Fax.: +90 212 285 2925.     

Photocrosslinkable acid urethane dimethacrylates from renewable natural oil and their use in the design of silver/gold polymeric nanocomposites

Castor oil-based acid urethane macromers were prepared and employed for obtaining Ag/Au/polymer nanocomposites. Structure and UV induced photopolymerization of the macromers were investigated by spectral methods. The polymerization rate and the degree of conversion decreased with about 10% in the presence of 2.5 wt.% silver nanoparticles (Ag NPs). For the diacid macromer, the surface plasmon intensity increased with irradiation time (the optical density of the absorption maximum (430 nm) attained 2.3 after 600 s), whereas a diminished efficiency was found for Ag NPs in situ generated. Transmission electron microscopy and X-ray photoelectron spectroscopy confirmed uniform distribution of the spherical nanoparticles (0.6 nm (Ag NPs); 5 nm (Au NPs)) and the appearance of Ag 3d_3/2, Ag 3d_5/2, Au 4f_7/2 and Au 4f_5/2 peaks corresponding to Ag (0) or Au (0). Environmental scanning electron microscope with energy-dispersive X-ray detector, contact angle and mechanical parameters measurements complemented the above observations.     

Transparent organic materials made from copolymerization of styrene with urethane‐methacrylate macromer. I. Monomacromer system

Urethane macromers were prepared by reacting tolylene diisocyanate with various glycols, followed by end capping with 2‐hydroxyethyl methacrylate in the presence of dibutyltin dilaurate as the catalyst. Various proportions of styrene to the urethane‐methacrylate macromer were adopted to cure at 70°C for 7–8 h. The effect of the composition on the properties was systematically studied. These transparent materials exhibited excellent mechanical and optical properties and heat deflection temperature. All of the copolymer sheets had a transmittance similar to the poly(methyl methacrylate) sheet and had a rather high refractive index. The mechanical and thermal properties varied with the ratio of styrene to macromer and with the kind of glycol used in the synthesis of the macromer. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 348–357, 2001     

Engineering Plastics from Lignin XIV. Characterization of Chain-Extended Hydroxypropyl Lignins

Abstract

Three series of chain-extended hydroxypropyl lignins (CEEQLs), prepared fran oqanosolv and kraft lignin, were examined regarding their chemical, molecular weight and them1 characteristics. Results showed that the molar substitution (MS) of propylene oxide, which was defined as the number of propoxy repeat units which comprise the chain attached to a single reactive site on lignin, varied and affected copolymer properties. As the MS increased from 1 to 7.2, the number average molecular weight (M_g) increased while the glass transition temperature (T_g) decreased. The actual M_g observed by GPC exceeded however that expected on the basis of mass gain by derivatization. This was attributed to changes in the apparent hydrodynamic volume in relation to MS. The change in T_g with increasing MS followed the Gordon-Taylor relationship. Differences in the chemical composition of the original lignin (organosolv or Kraft) were not obvious as the lignin content of the copolymer decreased below 50%.     

Effect of macromer synthesis time on the properties of the resulting poly(β‐amino ester) degradable hydrogel

Poly(β‐amino ester) biodegradable hydrogels are common in biomedical applications because of their tunable properties and similarities to natural soft tissue. Previous work has shown property adjustments through the choice of monomers, the ratio between monomers and the addition of a crosslinking component. Here, we show that the reaction time for the creation of the macromer can affect the resulting hydrogel properties, and thus provides another method of tuning properties. Macromer was created through the reaction of isobutylamine with poly(ethylene glycol) diacrylate (n = 400). The reaction progress was analyzed using IR and GPC analysis. Hydrogels were created through UV photopolymerization from macromers synthesized for 24, 36, and 48 h. The degradation, compressive moduli, and swelling were measured in an aqueous solution. All showed significant differences between hydrogels of different macromer synthesis times. These differences likely stem from the incomplete macromer synthesis reaction and resulting PEG‐rich regions in hydrogels from shorter synthesis times. These regions will not readily degrade, but do increase the mechanical properties and extent of swelling. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of an EPDM graft terpolymer

Summary An EPDM graft terpolymer was prepared using the macromer poly--methylstyryldicyclopentadiene (P-MSt-DCp) as the diene with ethylene and propylene. The new material was characterized by GPC, osmometry, nmr spectrometry, and TGA measurements. Number average molecular weights are in the 24,000–29,000 range, and the polymer carries two branches per chain.     

Silyl sulfonate approach to the synthesis of a block copolydimethylsiloxane-polydioxepane

Block copolydioxepane-polydimethylsiloxane has been synthesized by the “silyl sulfonate approach.” The nucleophilic macromer, lithium polydimethylsiloxane, was reacted with chlorodimethylsilane or allylchlorodimethylsilane to produce the corresponding macromers with a labile substituent, namely an allyl or a hydride, on silicon. These macromers were then converted to the electrophilic polydimethylsiloxane arylsulfonates, which initiated the cationic polymerization of 1,3-dioxepane to yield block polydimethylsiloxane-polydioxepane in the presence of 2,6-di-t-butylpyridine.     

环氧丙烷开环聚合反应的工程研究 (Ⅱ)间歇和半连续操作时聚醚的数均分子量和双键度

本文通过实验考察了间歇和半连续操作时聚醚的数均分子量和双键度与反应条件之间的关系,并在此基础上,运用数学方法导出了这种操作方式下聚(?)的数均分子量和双键度的半经验模型。经实验结果的检验,这些半经验模型具有较高的准确性。     

Rheological properties of semidilute solutions of poly(acrylic acid) modified with hydrocarbon and fluorocarbon end‐capped poly(ethylene glycol) macromonomer

Hydrocarbon and fluorocarbon end‐capped poly(ethylene glycol) (PEG) macromonomers with 9, 23, and 45 ethylene oxide units were synthesized by the esterification method. Copolymerization of these macromers with acrylic acid (AA) resulted in hydrophobically grafted poly(AA)s (PAAs) containing different lengths of PEG spacers. Their solution properties were investigated by rheological measurements and compared to those without hydrocarbon and fluorocarbon groups and without PEG spacers. Evident hydrophobic association was found to exist in the aqueous solution of these hydrophobically grafted copolymers, and the associating efficiency was improved by the flexible PEG spacer compared to those counterparts without them. However, the intramolecular association became predominant with the spacer length increase and the solution viscosity decreased. A wide viscosity plateau was observed for macromer modified polyelectrolytes in the alkalization process, which was unavailable for hydrophobically modified ones without PEG spacers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 12: 2777–2783, 2003     

The chain extension of anionic prepolymers in the preparation of aqueous poly(urethane–urea) dispersions

Anionic polyurethane prepolymers end‐capped with isocyanate groups were dispersed and chain‐extended in aqueous media using three different extension agents: hydrazine, 1,2‐ethylene diamine (EDA) and 1,2‐propylene diamine (PDA). Two types of prepolymer were used. The first was prepared from isophorone diisocyanate (IPDI), α,α‐dimethylol propionic acid (DMPA) and poly(propylene oxide) diol (PPO) and the second from α,α,α′,α′‐tetramethyl‐1,3‐xylylene diisocyanate (m‐TMXDI), poly(caprolactone) diol (PCL) and DMPA. The colloidal particles which formed in the dispersion process and the constituent poly(urethane–urea) chains were characterised by a combination of dynamic and static light scattering, gel permeation chromatography and FTIR spectroscopy. Using EDA as the extender, a study was made of how the degree of extension depended on the molar ratio of amine to isocyanate groups, [NH₂]/[NCO] (= R_{A, I}). It was found that using a stoichiometric balance of isocyanate and amine groups did not lead to high degree of extension, and better chain extension was obtained at lower R_{A, I} values. In a comparative study using stoichiometric balances of isocyanate and amine groups, the degrees of extension obtained using PDA and EDA were approximately the same, while hydrazine was the least effective. Force–extension studies were carried out on samples prepared from films cast from the aqueous poly(urethane–urea) dispersions in order to assess the influence of chain‐extender type and stoichiometry on bulk properties; values of Young's modulus, tensile strength and maximum extension are reported. Copyright © 2003 Society of Chemical Industry     

In Situ Dynamic Measurement of Polydisperse Chain Aggregate Aerosols Using Photocorrelation Spectroscopy Technique

An experimental technique was developed to perform in situ photo correlation spectroscopy measurements on length distribution of dynamic polydisperse iron oxide aerosols with diameters ranging from 0.01 to 0.05 μm. The cumulant analytical method is used to determine the average length of the chain aggregate. The experimental results show that the average length of the iron oxide aerosols obtained by the photo correlation spectroscopy technique is basically consistent with the results obtained by TEM. Results indicate that the length of the iron oxide samples increases as the liquid carbonyl temperature increases and the gas flow dilution ratio decrease.