Specific refractive index increments of segmented polyurethanes

Dostál, Jiřı́; Šimek, Lubomı́r; Kašpárková, Věra; Bohdanecký, M.

doi:10.1002/(sici)1097-4628(19980620)68:12<1917::aid-app4>3.3.co;2-0

Cited by 3 publications

(8 citation statements)

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“…Our results obtained using Table 4 show that 0 Х 0.040 (corresponding to BD) and dn/dw d Х 0.156 [obtained from the value of MDI ϩ BD and Eq. (10) for w d ϭ 1] are in the range of literature data and lead to values for PUS-1 to PUS-5 in the broad span reported for polyurethanes (0.039-0.18 cm 3 /g) (5,19,28).…”

Section: Specific Refractive Index Increments Of Segmented Polyurethanessupporting

confidence: 57%

“…The 0 and d/dw d coefficients in the dependence between the specific refractive index increments and the weight fraction of MDI units, w d , have been evaluated and the results are situated between the values reported in literature (19).…”

Section: Discussionmentioning

confidence: 70%

“…The literature (19) shows that this neglect is justified for polyurethanes with low MDI concentrations. The literature (19) shows that this neglect is justified for polyurethanes with low MDI concentrations.…”

Section: Specific Refractive Index Increments Of Hard and Soft Segmentsmentioning

confidence: 99%

“…For the polyurethanes containing PEGA, MDI, and BD, investigated by Schulz et al (16), 0 ϭ 0.035 cm 3 /g and d/dw d ϭ 0.168 cm 3 /g, and for polyuretanes containing MDIϩBD, poly(-caprolactone) (PCL) or polybutylene adipate (PBA) with MDI and BD, investigated by Dostal et al (19), 0 ϭ 0.046 cm 3 /g and d/dw d ϭ 0.160 cm 3 /g. Our results obtained using Table 4 show that 0 Х 0.040 (corresponding to BD) and dn/dw d Х 0.156 [obtained from the value of MDI ϩ BD and Eq.…”

Section: Specific Refractive Index Increments Of Segmented Polyurethanesmentioning

confidence: 99%

“…These dependences become complicated for copolymers containing three or more components largely differing in refractivity. Bohdanecky et al (19) compared the experimental results with those obtained using Vogel (20), Gladstone-Dale (21), or Lorenz-Lorentz (22,23) equations. Schulz et al (16) found a good correspondence of the experimental values with those calculated from group contributions to the molar refraction, using the method proposed by Goedhart (17) and van Krevelen (18).…”

Section: Introductionmentioning

confidence: 99%

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Specific Refractive Index Increments of Polyurethane/Polydimethylsiloxane Segmented Copolymers

Ioan¹,

Grigorescu²,

Stanciu³

2000

Polymer-Plastics Technology and Engineering

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New polydimethylsiloxane-containing segmented block copolyurethanes were obtained from aromatic or aliphatic diisocyanates, 1,4-butanediol and poly(ethylene glycol)adipate using a multistep polyaddition process. Specific refractive index increments of these segmented copolymers in N,N-dimethyl-formamide have been determined by the Lorenz-Lorentz equation and the corresponding group contributions to the molar refraction and to the molar volume. The results are in good agreement with the experimental values. Also, from the dependence between the specific refractive index increments and the weight fraction of 4,4Ј-methylene diphenylene diisocyanate units, w d , the 0 and d/dw d coefficients have been evaluated and the results are situated between the values reported in literature.

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Section: Specific Refractive Index Increments Of Segmented Polyurethanessupporting

confidence: 57%

Section: Discussionmentioning

confidence: 70%

Section: Specific Refractive Index Increments Of Hard and Soft Segmentsmentioning

confidence: 99%

Section: Specific Refractive Index Increments Of Segmented Polyurethanesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Specific Refractive Index Increments of Polyurethane/Polydimethylsiloxane Segmented Copolymers

Ioan¹,

Grigorescu²,

Stanciu³

2000

Polymer-Plastics Technology and Engineering

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Rare-Earth Amidate Complexes. Easily Accessed Initiators For ε-Caprolactone Ring-Opening Polymerization

2008

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The direct synthesis of yttrium amidate complexes using the simple reaction of amide proligands and Y(N(SiMe3)2)3 results in the high-yielding preparation and isolation of crystalline, monomeric materials. The complex, tris(N-2',6'-diisopropylphenyl(naphthyl)amidate)yttrium mono(tetrahydrofuran) (4), was structurally determined to be a 7-coordinate C1 symmetric structure, maintaining one bound tetrahydrofuran molecule. Compound 4 (C12H17[NCO]C10H7)3Y(C4H8O) crystallized in the monoclinic space group P2(1)/c with a = 13.7820(11) A, b = 33.598(3) A, c = 16.0575(12) A, alpha = 90 degrees, beta = 98.762(3) degrees, gamma = 90 degrees, Z = 4. Solution phase NMR spectroscopic characterization of this same complex showed a highly symmetric species, consistent with a fluxional coordination environment for these compounds. Preliminary studies into the initiation of epsilon-caprolactone ring-opening polymerization using these complexes indicate high activity, producing high molecular weight polymer.

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Molecular design of some semi-alicyclic polyimides as a route to improve refraction and dielectric properties for liquid crystal display applications

Barzic¹,

Albu²,

Ioanid³

et al. 2017

High Performance Polymers

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The study establishes an adequate monomer combination for achieving the best balance of properties required in obtaining polyimide alignment layers for display devices. The molecular design of some aliphatic/aromatic polyimides was performed by using dianhydride monomers with distinct configurations in terms of rigidity, size, and symmetry. The polyimides based on semi-flexible and nonsymmetric dianhydride moieties present lower refractive index and dielectric constant (<3) than those obtained from symmetric and rigid dianhydride units. This determines faster traveling of visible and microwave radiations as required for liquid crystal alignment purposes. The interactions of samples with the N-(4-Methoxybenzylidene)-4-butylaniline, cyanobiphenyl, and 4-pentyl-4-cyanobiphenyl nematics were assessed. The analyzed polyimides have higher surface tensions than the ones of the liquid crystals, determining a parallel arrangement of the nematic molecules. As the dispersive interactions at the polymer surface are lower, the work of spreading is higher as a result of improved adhesion of liquid crystal with the polyimide alignment layer. The sample containing rigid, symmetric, noncoplanar dianhydride units (PI.4) and the one based on semi-flexible, nonsymmetric dianhydride moieties are the most transparent for visible and microwave radiations, allowing low cohesion interaction at interface with nematics. These aspects recommend the two studied polyimides as candidates for alignment layers.

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Specific refractive index increments of segmented polyurethanes

Cited by 3 publications

References 0 publications

Specific Refractive Index Increments of Polyurethane/Polydimethylsiloxane Segmented Copolymers

Specific Refractive Index Increments of Polyurethane/Polydimethylsiloxane Segmented Copolymers

Rare-Earth Amidate Complexes. Easily Accessed Initiators For ε-Caprolactone Ring-Opening Polymerization

Molecular design of some semi-alicyclic polyimides as a route to improve refraction and dielectric properties for liquid crystal display applications

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