Synthesis of a novel [60]fullerene pearl-necklace polymer,poly(4,4′-carbonylbisphenylene trans-2-[60]fullerenobisacetamide)

A novel [60]fullerene pearl-necklace polymer, poly(4,4′-carbonylbisphenylene trans-2-[60]fullerenobisacetamide), was synthesized by a direct polycondensation of trans-2-[60]fullerenobisacetic acid with 4,4′-diaminobenzophenone in the presence of large excesses of triphenyl phosphite and pyridine. In the present polymer, [60]fullerene pearls and diamine linkers were attached to each other by methano-carbonyl connectors. The molecular weight M_w of the polymer was determined to be 4.5 × 10⁴ on the basis of the TOF-MS, and a GPC analysis of the polymer using polystyrene standards showed a weight-average molecular weight of 5.3 × 10⁴. The UV-vis spectrum of the resultant polymer in N,N-dimethylacetamide (DMAc) exhibited a broad absorption (λ_max 310 nm, ε 2.1 × 10⁴ L · mol⁻¹ · cm⁻¹), tailing to longer wavelengths, and a fluorenscence peak centered at 550 nm was observed in DMAc. There was observed a large downfield-shift of the cyclopropane methyne proton in the ¹H-NMR spectra from 4.57 ppm of the ethyl ester to 5.78 ppm of the polyamide. These observations indicate that the present polyamide is a high-molecular-weight [60]fullerene pearl-necklace polymer and that the cyclopropane rings are efficient to make the [60]fullerene cages and the diamine components conjugatable. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3632–3637, 1999     

Aggregation behavior of polystyrene‐b‐poly(ethylene/butylene)‐b‐polystyrene triblock copolymer in N‐methylpyrrolidone

Solution property of hydrogenated polystyrene‐b‐poly(ethylene/butylene)‐b‐polystyrene triblock copolymer (SEBS copolymer) was studied by using static light scattering and dynamic light scattering for cyclohexane and N‐methylpyrrolidone (NMP) solutions. From the values of dimensionless parameters ρ, defined as the ratio of radius of gyration 〈S²〉^1/2 to hydrodynamic radius R_H, and solubility parameters, SEBS copolymer proved to exist as single chain close to random coil in nonpolar cyclohexane, whereas aggregate into the core‐shell micelle consisting of poly(ethylene/butylene) (PEB) core surrounded by PS shell in polar NMP. The core‐shell micelle formed in NMP is composed of 65 polymer chains, having three times larger average chain density (d = 0.12 g cm^?3) than a single polymer chain (d = 0.04 g cm^?3) in cyclohexane. The comparison with the aggregation behaviors in other solvents demonstrated that the aggregate compactness of the copolymer depended largely on solvent polarity, resulting in formation of the highly dense PEB core (R_c = 4.5 nm) and the thick PS shell (ΔR = 22.9 nm) in high‐polar NMP. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 588–594, 2010     

Internal organization and conformational characteristics of star-shaped polystyrene with fullerene C<Subscript>60</Subscript> as a branching center in deuterotoluene

The internal organization of star-shaped polystyrene macromolecules containing fullerene C₆₀ as a branching center is studied via small-angle neutron scattering in deuterotoluene. Analysis of the experimental data according to the Debye-Benoit approximation and the Fourier transformation of the momentum transfer dependences of scattering cross sections for the linear PS precursor and stars is used to determine their molecular masses (9 × 10³ and 5 × 10⁴) and gyration radii (∼2.7 and ∼5.5 nm), the gyration radius of the arm (∼3.4 nm), and the average functionality of the star (5.7). The behavior of scattering cross sections for the fullerene-containing polymer on the whole is described by the law of scattering for stars with Gaussian arms (the Benoit model). However, at the local level (within one chain segment), the fullerene center exerts a specific effect on the conformation of arms. As a result, their statistical flexibility decreases and eventually the size of the star increases by ∼30%. This finding conflicts with the Daoud-Cotton theory.     

Effect of fullerene C60 branching center on the conformational properties of arms and the structure of star-shaped polystyrenes in solutions

The effect of the fullerene C₆₀ branching center on the structure and conformation of star-shaped polystyrenes with different arm lengths at equal concentrations in deuterotoluene (c = 1 g/dL) is studied by the method of small-angle neutron scattering. The analysis of neutron scattering for linear PS precursors and stars (the molecular masses of arms are ～7 × 10³ and ～4 × 10⁴) shows that the stars have ～6 arms that form a dense excluded-volume zone around a core inaccessible to other macromolecules. In low-molecular-mass stars (the molecular mass of the arm is ～7 × 10³), strengthening of the static rigidity of arms is observed; as a result, the size of arms increases relative to the size of free PS chains in a good solvent. At a greater length of arms (M ～ 4 × 10⁴), their individual properties are weakly pronounced in the correlation spectrum of the arm because of the interpenetration of arms, thereby demonstrating similarity in the structures of stars and their linear analogs. The mechanism controlling the effect of fullerene C₆₀ on the conformations of stars via solvent structuring by fullerene is discussed.     

Anionic copolymerization of [60]fullerene with styrene initiated by sodium naphthalene

The novel C₆₀–styrene copolymers with different C₆₀ contents were prepared in sodium naphthalene-initiated anionic polymerization reactions. Like the pure polystyrene, these copolymers exhibited the high solvency in many common organic solvents, even for the copolymer with high C₆₀ content. In the polymerization process of C₆₀ with styrene an important side reaction, i.e., reaction of C₆₀ with sodium naphthalene, would occur simultaneously, whereas crosslinking reaction may be negligible. ¹³C-NMR results provided an evidence that C₆₀ was incorporated covalently into the polystyrene backbone. In contrast to pure polystyrene, the TGA spectrum of copolymer containing ∼ 13% of C₆₀ shows two plateaus. The polystyrene chain segment in copolymer decomposed first at 300–400°C. Then the fullerene units reptured from the corresponding polystyrene fragments attached directly to the C₆₀ cores at 500–638°C. XRD evidence indicates that the degree of order of polymers increases with the fullerene content increased in terms of crystallography. Incorporation of C₆₀ into polystyrene results in the formation of new crystal gratings or crystallization phases. In addition, it was also found that [60]fullerene and its polyanion salts [C₆₀ⁿ⁻(M⁺)_n, M = Li, Na] cannot be used to initiate the anionic polymerization of some monomers such as acrylonitrile and styrene, etc.© 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2653–2663, 1998     

Tapered copolymers of styrene and 4-vinylbenzocyclobutene via carbanionic polymerization for crosslinkable polymer films

Well-defined polystyrene homopolymers with surface-adhesive triethoxysilyl end group were synthesized via living carbanionic polymerization, epoxide end-functionalization and subsequent hydrosilylation with triethoxysilane. Grafting-to performance of polymers with various molecular weight (M_n = 3000–14,000 g mol⁻¹) to a silicon surface was examined in dependence of reaction time, polymer concentration, solvent and number of alkoxysilyl end groups. Crosslinkable polymers for surface modification were synthesized by statistical carbanionic copolymerization of 4-vinylbenzocyclobutene (4-VBCB) and styrene, followed by epoxide end-functionalization and triethoxysilane modification (M_n = 4000–14,000 g mol⁻¹). The copolymers were characterized by ¹H-NMR, THF-SEC, and matrix-assisted laser desorption and ionization time-of-flight mass spectrometry. In situ ¹H-NMR kinetic studies in cyclohexane-d₁₂ provided information regarding the monomer gradient in the polymer chains, with styrene being the more reactive monomer (r_s = 2.75, r_4-VBCB = 0.23). Thin polymer films on silicon wafers were prepared by grafting-to surface modification under conditions derived for the polystyrene homopolymer. The traceless, thermally induced crosslinking reaction of the benzocyclobutene units was studied by DSC in bulk as well as in 3–6 nm thick polymer films. Crosslinked films were analyzed by atomic force microscopy, ellipsometry, and nanoindentation, showing smooth polymer films with an increased modulus. © 2019 The Authors. Journal of Polymer Science published by Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 181–192     

Synthesis and Structural Characterization of Three New Inorganic ＂Host-gues＂ Polyoxomolybdates

Since two interesting inorganic “host‐guest” polyoxomolybdates 1 and 2 have been reported previously, we have now succeeded in selectively isolating three new acetated “host‐guest” polyoxomolybdates 3–5, which considerably extend the range of structures in the cyclic polyoxomolybdate catalogue. 3 crystallizes in the triclinic space group P‐1 with a = 1.22235(1) nm, b = 1.52977(2) nm, c = 1.54022(1) nm, a = 113.746(1)°, β = 96.742(1)°, γ = 101.564(1)°, V = 2.51892(4) nm³, Z =1, D_c = 2.568 g. cm^?3. 4 and 5 crystallize in the monoclinic system: P2(1)/n, a = 1.08298(2) nm, b = 1.54029(1) nm, c = 2.78893(5) nm, β =94.2730(10)°, V = 4.63929(12) nm³, Z = 2 and D_c = 2.671 g. cm^?3 for 4, and C2/c, a =2.59907(8) nm, b = 1.65992(3) nm, c = 2.28473(7) nm, β‐93.4370(10)°, V = 9.8392(5) nm³, Z = 4 and D_c = 2.556 g. cm^?3 for 5. The structures of 3, 4 and 5 consist of 18‐membered “host‐guest” polyoxoanions [ Na (X)₂| ∈ |(μ_3‐OH)₄Mo^y₈Mo^VI₁₀52(μ₂‐CH₃COO)₂]^?(R+9 (X = CH₃COO^?for 3, DMF for 4 and H₂O for 5), which are connected via Na* ions or hydrogen bonds into infinite extended frameworks.     

CRITICAL CONCENTRATIONS OF α(1→3)-D-GLUCAN FROM LENTINUS EDODES IN NaOH AQUEOUS SOLUTION

Critical concentrations of α-(1→3)-D-glucan L-FV-Ⅱ from Lentinus edodes were studied by viscometry andfluorescence probe techniques. The dependence of the reduced viscosity on concentration of the glucan in 0.5 mol/L NaOHaqueous solutions with or without urea showed two turning points corresponding to the dynamic contact concentration c_s andthe overlap concentration c~* of the polymer. The values of c_s and c~* were found to be 1×10~(-3) g cm~(-3) and 1.1×10~(-2) g cm~(-3),respectively, for L-FV-Ⅱ in 0.5 mol/L NaOH aqueous solutions. The two critical concentrations of L-FV-Ⅱ in 0.5 mol/LNaOH aqueous solutions were also found to be 1.2×10~(-3) g cm~(-3) fbr c_s and 9.2×10~(-3) g cm~(-3) for c~* from the concentrationdependence of phenanthrene fluorescence intensities. The overlap concentration c~* of L-FV-Ⅱ in 0.5 mol/L NaOH aqueoussolutions was lower than that of polystyrene with same molecular weight in benzene, owing to the fact that polysaccharidetends to undergo aggregation caused by intermolecular hydrogen bonding. A normal viscosity behavior of L-FV-Ⅱ in 0.5 mol/L urea/0.5 mol/L NaOH aqueous solutions can still be observed in an extremely low concentration range at 25℃.     

Polymer‐Fullerene Network Formation via Light‐Induced Crosslinking

A facile and efficient methodology for the formation of polymer‐fullerene networks via a light‐induced reaction is reported. The photochemical crosslinking is based on a nitrile imine‐mediated tetrazole‐ene cycloaddition reaction, which proceeds catalyst‐free under UV‐light irradiation (λ_max = 320 nm) at ambient temperature. A tetrazole‐functionalized polymer (M_n = 6500 g mol⁻¹, Ð = 1.3) and fullerene C₆₀ are employed for the formation of the hybrid networks. The tetrazole‐functionalized polymer as well as the fullerene‐containing networks are carefully characterized by NMR spectrometry, size exclusion chromatography, infrared spectroscopy, and elemental analysis. Furthermore, thermal analysis of the fullerene networks and their precursors is carried out. The current contribution thus induces an efficient platform technology for fullerene‐based network formation.

     

Degradation on freezing dilute polystyrene solutions in p-xylene

Chain scission was observed during the crystallization of p-xylene in dilute polystyrene solutions. Degradation yields were determined by gel permeation chromatography, as a function of the number of freeze-and-thaw cycles, polymer concentration, and initial polymer molecular weight (M). The rate constant for chain scission K_c increases with the polymer chain length, from 0.021%/cycle at M = 110·10³ to 4.7%/cycle at M = 8.5·10⁶. Over the two decades range of investigated molecular weights, K_c follows an empirical scaling law of the form K_c ～ (M ? M_lim)^1.17578, where M_lim is a limiting molecular weight ? 29,000 g. mol^?1 below which no degradation could be induced. Some propensity for midchain scission was detected, although this tendency was much weaker in comparison to flow-induced degradation. A chain scission model based on crack propagation failed to reproduce the experimental results. To explain the observed dependence of K_c with the square of the radius of gyration, an interfacial stress transmission mechanism between the crystallization fronts and the polymer coil has been proposed. © 1994 John Wiley & Sons, Inc.     

Polymeric nanocomposite comprising gold nanoparticles and bilaterally sulfur‐functionalized polystyrene

Anionic polymerization technique has been utilized to synthesize a bilaterally sulfur‐functionalized polystyrene, SCH3‐polystyrene‐SH. The synthesis scheme consists of (1) initiation of 4‐vinylbenzylmethyl sulfide with sec‐butyllithium to form a living sulfur‐containing initiator, (2) polymerization of styrene, and (3) termination of growing polystyrene chain with ethylene sulfide. The resulting bilaterally sulfur‐functionalized polystyrene is used to make polystyrene/gold nanoparticles (AuNPs) nanocomposite with AuNPs formed in situ in polymer solution through reduction of AuClO₄. The effects of the polymer/Au molar ratio as well as the molecular weight of polymer on the size and dispersion of formed AuNPs have been studied, and the superiority of bilaterally functionalized polymer to unilaterally functionalized polymer has been demonstrated. The polystyrene/AuNPs composite has been characterized by GPC, ¹H‐NMR, ¹³C‐NMR, EDS, TEM, UV‐Vis, and DSC. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1268–1277     

一个新颖的含联二萘芬衍生物的镉配合物的合成和晶体结构

The self-assembly of a racemic exo-bidentate ligand 2,2＇-bis（4-pyridylmethyloxy）-1,1＇-binaphthyl, namely Rac-L, with cadmium（Ⅱ） salt gave rise to a new one-dimensional polymer, which has been characterized by single crystal X-ray diffraction analysis. The polymer crystallizes in a triclinic space group P-1 with unit cell parameters： a=0.6976（1） nm, b= 1.30160（14） nm, c= 1.71146（17） nrn.α= 105.141（3）°, β=94.263（5）°, γ= 100.405（4）°, V= 1.4633（2） nm^3, Z=2, C32H29CdCl2N2O4.5, M=696.88, Dc= 1.584 g/cm^3, F（000）=708,μ（Mo Kα）=0.972 mm^-1. The final R and wR are 0.0498 and 0.1282 for 5079 observed reflections with I≥2σ（I）.     

Rheological and microcalorimetric studies of a model alkali‐soluble associative polymer (HASE) in nonionic surfactant solutions

Rheological experiments were carried out on a 1 wt % hydrophobically modified alkali‐soluble emulsion (HASE) solutions at pH ∼ 9 in the presence of nonionic polyoxyethylene ether type surfactant (C₁₂EO₂₃). The low shear viscosity and dynamic moduli increases at c > cmc until they reach a maximum at a critical concentration, c^m of approximately 1 mM (∼17 times the cmc of free surfactant) and then decrease. The dominant mechanism at cmc < c < c^m is an increase in the number of intermolecular hydrophobic junctions and a strengthening of the overall associative network structure. Above c^m, the disruption of the associative network causes a reduction in the number of junctions and strength of the overall network structure. The influence of C₁₂EO₂₃ on HASE before cmc could not be detected macroscopically by the rheological technique. However, isothermal titration calorimetry enables the determination of complex binding of surfactant to the polymer. Isothermal titration of C₁₂EO₂₃ into 0.1 wt % HASE indicates that the C₁₂EO₂₃ aggregation in water and 0.1 wt % HASE polymer solutions is entropically driven. A reduction in the critical aggregation concentration (cac) confirms the existence of polymer–surfactant interactions. The hydrophobic micellar junctions cause a decrease in the ΔH and ΔS of aggregation of the nonionic surfactant. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2019–2032, 2000     

Large Nonlinear Optical Activity of a Near-infrared-absorbing Bithiophene-based Polymer with a Head-to-head Linkage

Although the production of near-infrared (NIR)-absorbing organic polymers with an excellent nonlinear optical (NLO) response is vital for various optoelectronic devices and photodynamic therapy, the molecular design and relevant photophysical investigation still remain challenging. In this work, large NLO activity is observed for an NIR-absorbing bithiophene-based polymer with a unique head-to-head linkage in the NIR region. The saturable absorption coefficient and modulation depth of the polymer are determined as ∼−3.5×10⁵ cm GW⁻¹ and ∼32.43%, respectively. Notably, the polymer exhibits an intrinsic nonlinear refraction index up to ∼−9.36 cm² GW⁻¹, which is six orders of magnitude larger than that of CS₂. The maximum molar-mass normalized two-photon absorption cross-section (σ₂/M) of this polymer can be up to ∼14 GM at 1200 nm. Femtosecond transient absorption measurements reveal significant spectral overlap between the 2PA and excited state absorption in the 1000–1400 nm wavelength range and an efficient triplet quantum yield of ∼36.7%. The results of this study imply that this NIR-absorbing polymer is promising for relevant applications.     

Synthesis, Structure and Biological Activities of Novel Triazole Compounds Containing 4,6-Dimethyl-pyrimidin-2-ylthio Group

Introduction As an important type of fungicides, triazole com-pounds are highly efficient, low poisonous and inward absorbent.1-3 At present, the studies on triazole deriva-tives are mainly concentrated on compounds with tria-zole as the only active group. The report on triazole compounds that contain both triazole group and other active group in a single molecule has rarely been found. Some pyrimidines have been used as highly efficient and lowly poisonous fungicides4 in controling powdery mi…     

Eight-arm star polystyrene in methylcyclohexane: Cloud-point curves,critical lines,and coexisting densities and viscosities

We measured the cloud-point curves of eight-arm star polystyrene (sPS) in methylcyclohexane (MCH) for polymer samples of three total molecular masses [weight-average molecular weight (M_w) × 10⁻³ = 77, 215, or 268]. We found a downward shift of 5–15 K in the critical temperature (T_c) of the star polymer solutions with respect to linear polystyrene (PS) solutions of the same M_w. The shift in T_c became smaller as M_w increased. The critical volume fraction for eight-arm sPS in MCH was equal within experimental uncertainty (10–40%) to that of linear PS in MCH. For sPS of M_w = 77,000 in MCH, we studied the mass density (ρ) as a function of temperature (T). As for linear polymers in solution, the difference in ρ between coexisting phases (Δρ) could be described over t = (T_c − T)/T_c for 1.1 × 10⁻⁴ < t < 4.7 × 10⁻³ with the Ising value of the exponent β in the expression Δρ = B t^β. Both ρ(T) above T_c and the average value of ρ below T_c were linear functions of temperature; no singular corrections were observed. The measurements of the shear viscosity (η) near T_c for sPS (M_w = 74,000) in MCH indicated a strong critical anomaly in η, but the data were not precise enough for a quantitative analysis. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 129–145, 2004     

Effects of composition drift on the effectiveness of random copolymer reinforcement at polymer–polymer interfaces

Random copolymer layers are surprisingly effective at reinforcing polymer–polymer interfaces. One hypothesis is that composition drift during synthesis can account for the higher than expected toughening. To test this hypothesis, we polymerized a series of poly(d‐styrene‐r‐2‐vinylpyridine) (dPS_f‐r‐PVP_1?f) copolymers with various fractions (f) of deuterated styrene to only 10% completion to avoid composition drift. The fracture energies (G_c) of polystyrene/dPS‐r‐PVP/poly(2‐vinylpyridine) interfaces with relatively thick layers of dPS‐r‐PVP were measured. G_c decreased relative to interfaces reinforced with composition‐drifted dPS‐r‐PVP. Conversely, G_c increased when two or more copolymers were blended together. In such samples, the copolymers form distinct layers with multiple interfaces characterized by the difference in f (Δf) between adjacent layers. We find that G_c is governed by Δf_max, the largest difference in adjacent compositions, and, therefore, by the width of the narrowest interface (w_min). G_c increases strongly as w_min increases from 3 to 5 nm. Remarkably, these w_min values are about half the entanglement spacing in bulk polystyrene. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2363–2377, 2001     

两个双核铁（Ⅲ）和三足配体的配合物的合成和晶体结构

运用三足四齿配体三（2－甲基吡啶）胺（TPA）或三（2－甲基苯丙咪唑）胺（TBA）,得到两个双核铁(III)配合物，[Fe₂L₂(μ₂-O)(μ₂-p-NH₂-C₆H₄COO)]³⁺ (L = TPA, 1 和 L = TBA, 2)。两个配合物均为单斜晶系，空间群为P2(1)/c.晶胞参数 1: a = 1.4529(4), b = 1.6622(5), c = 2.0625(6) nm, β= 100.327(5)º, V = 4.900(3) nm³, z = 4, F(000) = 2344, 分子量M_r = 1142.91, Dc = 1.549 g/cm³, R₁ = 0.0544, R₂ = 0.0962. 2: a = 1.3378(4), b = 2.1174(7), c = 2.4351(7) nm, β= 97.315(6)º, V = 6.842(4) nm³, z = 4, F (000) = 3116, 分子量M_r = 1505.08, Dc = 1.444 g/cm³, R₁ = 0.0793, R₂ = 0.1623. 在两个双核铁(III)配合物中，中心的三价铁和配体TPA或TBA上的四个氮原子和两个氧原子通过不同的桥形成一个畸变的八面体构型。     

Relaxation dynamics of salt‐free polyelectrolyte solutions using flow birefringence and rheometry

Relaxation dynamics of salt‐free, aqueous solutions of sodium poly(styrene sulfonate) (NaPSS) were investigated by mechanical rheometry and flow birefringence measurements. Two semidilute concentration regimes were studied in detail for a range of polymer molecular weights. At solution concentrations c < 10 mg mL, limiting shear viscosity η₀ was found to scale with molecular weight and concentration as η₀ ∼ c^0.5M_w over nearly two decades in concentration. At higher solution concentrations, c > 10 mg mL, a change in viscosity scaling was observed η₀ ∼ c^1.5M, consistent with a change from simple Rouse dynamics for unentangled polyions to near‐perfect reptation dynamics for entangled chains. Characteristic relaxation times τ deduced from shear stress and birefringence relaxation measurements following start‐up of steady shearing at high rates reveal very different physics. For c < 10 mg mL, both methods yield τ ∼ c^−0.42M and τ ∼ c⁰M for c > 10 mg mL. Curiously, the concentration scalings seen in both regimes are consistent with theoretical expectations for salt‐free polyelectrolyte solutions undergoing Rouse and reptation dynamics, respectively, but the molecular weight scalings are not. Based on earlier light scattering studies using salt‐free NaPSS solutions, we contend that the unusual relaxation behavior is likely due to aggregation and/or coupled polyion diffusion. Simultaneous stress and birefringence measurements suggest that in concentrated solution, NaPSS aggregates are likely well permeated by solvent, supporting a loose collective of aggregated chains rather than the dense polymer aggregates previously supposed. Nonetheless, polyion aggregates of either variety cannot account for the inverse dependence of relaxation time on polymer molecular weight for c < 10 mg mL. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 825–835, 1999     

Novel polyisobutylene/poly(dimethylsiloxane) bicomponent networks. I. Synthesis and characterization

The synthesis of novel polyisobutylene (PIB)/poly(dimethylsiloxane) (PDMS) bicomponent networks is described. The synthesis strategy (see Figure 1) was to prepare well-defined and -characterized allyl-tritelechelic polyisobutylenes [ϕ(PIB—C—C=C)₃] and SiH-ditelechelic poly(dimethylsiloxanes) (HSi–PDMS–SiH) and then crosslink these moieties by hydrosilation. The ϕ(PIB—C—C=C)₃ was prepared by living isobutylene polymerization followed by end-quenching with allyltrimethylsilane, whereas the HSi–PDMS–SiH was obtained by equilibrium polymerization of octamethylcyclotetrasiloxane and tetramethyldisiloxane. The detailed structures of the starting polymers were characterized by GPC and ¹H-NMR spectroscopy. A series of PIB/PDMS bicomponent networks of varying compositions and average molecular weights between crosslinks (M _c) of ∼ 20,000 g/mol were assembled. Optimum crosslinking conditions were defined in terms of H₂PtCl₆ catalyst concentration, nature of solvent, time, temperature, and stoichiometry of ∼ CH₂CH=CH₂/∼SiH groups, allowing for the convenient synthesis of well-defined model bicomponent networks. Swelling studies and elemental analysis confirm the correctness of the synthetic strategy. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1891–1899, 1998