Polymerization of poly(dimethylsiloxane) macromers: 1. Copolymerization with styrene

The synthesis and characterization of methacrylate-ended macromers ($\text{M}\text{?}{}_{\mathrm{<mtext>n</mtext>}}$ 500 to 10 000) and their copolymerization with styrene (M₂) is described. The experimental errors in the values of the reactivity ratios r₁ render them meaningless. Values of r₂ can be determined with more precision and increase from 1.06 to 1.55 as the molecular weight of the macromer increases. This behaviour is due to steric effects, not diffusion-controlled propagation. It is shown that the assumptions that $\text{1 > r}{}_1\text{[}\text{M}{}_1\text{]}\text{[}\text{M}{}_2\text{]}$ and $\text{r}{}_2\text{>}\text{[}\text{M}{}_1\text{]}\text{[}\text{M}{}_2\text{]}$ are only valid for macromers of $\text{M}\text{?}{}_{\mathrm{<mtext>n</mtext>}}\text{> ca. 10 000}$.     

Cationic synthesis of macromers

Summary Unsaturated oxocarbenium salts were used to initiate the polymerization of THF. The macromers obtained were characterized carefully, and it was found that these species are well defined, of narrow molecular weight distribution, and fitted quantitatively with end standing polymerizable double bonds.     

Syntheses and polymerizations of macromers

Summary Living poly(tetrahydrofuran) (PTHF) was coupled with sodium p-vinylbenzyloxide quantitatively to prepare a macromer of p-vinylbenzyloxyl poly(tetrahydrofuran) (VBO-PTHF). The radical polymerization of the macromer with AIBN was performed. From the GPC measurement the conversion of the macromer to poly-macromer was shown to be high percentage, but the degree of polymerization of poly-macromer was much lower than that expected in the case of regular monomers such as styrene.     

Synthesis of polyethylene oxide macromers

Summary Anionic living polymerization of oxirane was shown to be efficient for the synthesis of polyethylene oxide macromers. The double bond at chainend was introduced either upon initiation or upon deactivation. The macromers obtained were characterized carefully to establish quantitatively the presence of the end-standing double bond. The species are well defined and of narrow molecular weight distribution.The authors are greatly indebted to Mr.E.Schuster and F.Isel for technical assistance.     

Synthesis of dicarboxylic acid functionalized polysiloxane macromers

Summary Methods to synthesize aliphatic and aromatic dicarboxylic acid functionalized polydimethylsiloxane macromers were studied. Introduction of allyl group into dicarboxylic acid as a substituent, followed by hydrosilylation by silane terminated polydimethylsiloxane was found satisfactory to obtain the macromers.     

Synthesis and reactions of methacryl-substituted siloxane macromers

Copolymerizations of two methacryl-terminated siloxane macromers (M _n=4000 and 23,00 g/mol) with styrene monomer were studied as a model of how reactive silicones may cross-link with unsaturated polyesters. Significant differences were found between the two macromers in the nature of the polymerization, the rate of reaction, the cloud point, and the products formed. The lower molecular weight macromer freely cross-links to form an insoluble three-dimensional network with styrene. The high molecular weight macromer reacts at only one terminal methacryl group and so forms a two-dimensional copolymer with styrene which melts like a thermoplastic and is soluble in organic solvents such as chloroform.This paper was presented at the Second International Topical Workshop, Advances in Silicon-Based Polymer Science.     

Synthesis of macromers of vinylchloride and vinylidene chloride from telomers

New macromers are prepared from monofunctional telomers of vinylidene chloride and vinylchloride obtained by redox catalysis or by means of radical initiators. Especially, model graft copolymers are obtained upon copolymerising these telomers with acrylic compounds.     

Synthesis and characterization of telechelic macromers containing fatty acid derivatives

Telechelic macromers end-capped with (meth)acrylic functionalities are the most commonly used materials in rigid, dental formulations. In order to provide higher flexibility to the final product (not necessarily for dental applications), long chain aliphatic fatty acid derivatives may be chosen. Thus, new telechelic macromers comprising methacrylic functionalities and dimer fatty acid derivatives have been synthesized for the first time, and their chemical structure is discussed in detail. Six different systems comprising ester, anhydride and urethane bonds were synthesized from non-toxic raw materials. FTIR spectroscopy and NMR analysis were used to evaluate chemical structure of new systems. Their molecular masses were estimated from GPC measurements and from an analytical method based on iodine value determination. The latter one proved to be very accurate in determining molecular masses of methacrylated telechelics according to a new method developed in this work. We demonstrated that, via simple organic chemistry, different architectures of telechelic macromers comprising commercially available, long chain derivatives of fatty acid, mainly linoleic acid, with α,ω-dihydroxy, α,ω-dicarboxy or α,ω-diamino functionalities were successfully synthesized. These macromers facilitate the development of new reactive (preferably, photocurable) flexible systems for potential biomedical applications.     

Synthesis of triglyceride-based urethane macromers and their use in copolymerization

Triglyceride oil-based urethane macromer (TGU) containing vinyl double bond was synthesized by the reaction of partial glyceride mixture (PGM) and methyl vinyl isocyanate (MVI). Free radical polymerization and copolymerization of TGU was studied. The structure of the TGU and polymers were elucidated by gel permeation chromatography (GPC) analysis, Fourier transform infrared spectroscopy (FT-IR) and ¹H nuclear magnetic resonance (¹H NMR) spectral measurements. The film properties of polymers were investigated by water resistance, alkali and acid resistance and contact angle measurements.     

Bioactive composites with designed interphases based on hyperbranched macromers

A series of designed interphases was produced by grafting chemically modified poly (aryl ether sulfones) (PSF) onto bioactive glass (BAG) particles. Macromolecular architecture, polymer morphology, composition and crosslink density of these PSF hybrid interphases were studied with respect to influence on mechanical properties. The hybrid PSF interphases improved mechanical strength by 20% over conventional silane treatments and increased the overall energy to failure by nearly 100%. The structure of the interphase was modeled with a three‐phase viscoelastic model. The results demonstrated the ability to engineer an interphase having hyperstructures containing mobile species and inorganic functionalities that improve adhesion and favor energy release during fracture processes. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1153–1166, 2006     

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.     

Preparation of PMMA macromers by o-vinylbenzylmagnesium chloride and their polymerization

Summary Polymerization of MMA with o-vinylbenzylmagnesium chloride was examined in toluene and in tetrahydrofuran (THF) at various temperatures. The polymer formed in toluene at –78°C was highly isotactic (mm=94%) and containing one vinylbenzyl group at the -end of the chain, although the methanol-soluble fraction concomitantly formed in an appreciable amount was less isotactic. The PMMAs formed in THF at –78 and –98°C were mostly methanol-soluble and highly syndiotactic (rr=88% at –78°C and 96% at –98°C), and also contained one vinylbenzyl group. The methanol-soluble, isotactic and syndiotactic PMMA macromers were polymerized or copolymerized with styrene by AIBN in toluene at 60°C. The isotactic macromer exhibited slightly higher reactivity than the syndiotactic one.     

Macroporous polymeric hydrogels formed from acrylate modified polyvinyl alcohol macromers

Macroporous polymeric hydrogels for the last several years have found broad application in areas connected with medicine, especially in such new disciplines as cell and tissue engineering. In present work a novel combine approach is proposed for preparation of polyvinyl alcohol macroporous hydrogels by cross-linking of polyvinyl alcohol acrylic derivatives in the presence of heterophase of frozen aqueous media. Hydrogels prepared using this method does not need additional structure fixing and are characterized by high thermal stability in swollen state sustaining even heating to more than 100 °С. The influence of different factors and reaction conditions on the cross-linked hydrogel formation process was studied. The high yield of products (80 ÷ 95%) was observed when reaction was conducted at temperature range −12 ÷ −18 °С, concentration of macromer 4–12 weight %, and amount of initiator 0.8 ÷ 1.6 mg/ml. Moreover, the equilibrium swelling of synthesized macroporous hydrogels was investigated and it was shown that synthesized cross-linked hydrogels are characterized by high water absorption which is weakly depended on solution pH and ionic force values.     

Engineering plastics from lignin. XVI. Starlike macromers with propylene oxide

Starlike macromers were prepared from hydroxypropyl organosolv lignin by reaction with propylene oxide, and they were analyzed by a combination of conventional analysis techniques. The average number of arms per macromer was controlled by partial capping with an alkoxy group; and the average length of arms by the degree of chain extension with propylene oxide. Analysis methods included treatment with hydriodic acid followed by gas chromatographic separation of alkyl iodides (HI/GC), UV spectroscopy, H-NMR spectroscopy, and thermal analysis. The results were consistent with a hypothetical pentameric model structure having between two and six radiating arms, each with a length of between 1 and 4 propylene oxide units. The UV method was best qualified to determine degree of chain extension, while HI/GC was best suited for analyzing average number of arms per macromer fragment. The synthesis and analysis of starlike macromers from lignin is viewed as an important stepping stone for the formulation of lignin-based engineering plastics and multiphase materials.     

Ionic conductivity in mixtures of salts with comb-shaped polymers based on ethylene oxide macromers

A comb-shaped polymer was prepared from a vinyl ether monomer comprising three oxyethylene units with a terminal methoxy group. The polymer could dissolve LiClO₄, NaClO₄, and LiSO₃CF₃ salts to form homogeneous amorphous mixtures, and the glass transition temperatures in each system were observed to increase with added salt. A.c. conductivity studies on the mixtures of polymer-LiClO₄ showed a dependence on both salt concentration and temperature. Room temperature conductivities were around 10^?5Scm^?1 rising to about 10^?3Scm^?1 at ～ 380K. A maximum in the conductivity was detected which altered with temperature. Conductivities which displayed non-Arrhenius behaviour were analysed using the Vogel-Tammann-Fulcher equation and interpreted on the basis of the configurational entropy model derived by Gibbs and coworkers.     

微乳液聚合和细乳液聚合

分别从微乳、细乳体系的形成,聚合机理及聚合特点等方断对两者进行了比较,并对各自的应用前景进行了展望。