H NMR and C NMR investigations of sequence distribution and tacticity in poly(vinyl alcohol-co-vinyl levulinate)

The microstructure of poly(vinyl alcohol-co-vinyl levulinate) (VOH-VLA copolymer) was studied by ¹H NMR and ¹³C NMR techniques. The sequence distributions could be obtained from the six methine triads observed in the 500-MHz ¹H NMR spectra of the copolymers: the three methylene dyads and the three carbonyl triads observed in 125.6-MHz ¹³C NMR spectra of the copolymers. The reaction activity order of different tacticity hydroxyl in PVA was found to be rr > mr > mm by investigating VOH-centered methine tacticity triads. The vinyl levulinate content (VLC), the number-average sequence length, dyad-triad relation and triad-triad relation (R) were calculated from methine triads, methylene dyads and carbonyl triads in ¹H NMR and ¹³C NMR spectra successfully, and they were in good agreement with each other. The consistency of the dyad-triad and triad-triad relations shows that head to head or tail to tail fragments are hardly present in VOH-VLA copolymer.     

Functionalized organic nanoparticles from core-crosslinked poly(4-vinylbenzocyclobutene-b-butadiene) diblock copolymer micelles

Surface-functionalized polymeric nanoparticles were prepared by: a) self-assembly of poly(4-vinylbenzocyclobutene-b-butadiene) diblock copolymer (PVBCB-b-PB) to form spherical micelles (diameter: 15-48 nm) in decane, a selective solvent for PB, b) crosslinking of the PVBCB core through thermal dimerization at 200-240 °C, and c) cleavage of the PB corona via ozonolysis and addition of dimethyl sulfide to afford aldehyde-functionalized nanoparticles (diameter: ∼16-20 nm), along with agglomerated nanoparticles ranging from ∼30 to ∼100 nm in diameter. The characterization of the diblock copolymer precursors, the intermediate micelles and the final surface-functionalized crosslinked nanoparticles was carried out by a combination of size exclusion chromatography, static and dynamic light scattering, viscometry, thermogravimetric analysis, ¹H NMR and FTIR spectroscopy and transmission electron microscopy.     

Neutral poly(3,4-ethylenedioxythiophene-2,5-diyl)s: preparation by organometallic polycondensation and their unique p-doping behavior

Neutral and non-doped poly(3,4-ethylenedioxythiophene), PEDOTh(Ni), and its hexyl derivative, PEDOTh-C₆(Ni), have been prepared by organometallic dehalogenation polycondensation of 2,5-dichloro-3,4-ethylenedioxythiophene and its hexyl derivative with a zerovalent nickel complex. PEDOTh-C₆(Ni) was soluble in organic solvents and ¹H NMR data indicated that it had an M_n of 11,000. MALDI-TOF mass analysis of PEDOTh(Ni) gave M_n and M_w of about 1700 and 2400, respectively. PEDOTh-C₆(Ni) showed a UV-Vis absorption peak at 546 nm in CHCl₃. Electrochemical oxidation of PEDOTh-C₆(Ni) started at about −0.40 V vs Ag⁺/Ag and gave a peak at 0.20 V vs Ag⁺/Ag. Chemical and electrochemical oxidation (or p-doping) of PEDOTh-C₆(Ni), both in solutions and in a solid state, led to weakening of the original π-π^∗ peaks and rise of new peak(s) in a region of 800-1500 nm. The p-doping of PEDOTh-C₆(Ni) caused not only a decrease in the intensity of ¹H NMR signals of the bridging ethylene hydrogens but also a decrease in that of the hexyl side chain, suggesting a strong interaction of the p-dopant with the side chain. NMR data of poly(3-methoxythiophene-2,5-diyl) also supported an assumption that p-doping brings about a severe change in electronic state of the substituent attached to the polythiophene main chain. PEDOTh(Ni) had a density of 1.71 g cm⁻³; the molecular packing mode of PEDOTh(Ni) is discussed based on the density of the polymer and its XRD data.     

Dimensions and viscosity behavior of polyelectrolyte brushes in aqueous sodium chloride. A polymacromonomer consisting of sodium poly(styrene sulfonate)

Nine samples of a polymacromonomer consisting of sodium poly(styrene sulfonate) and having a side-chain polymerization degree of 15 are investigated by light scattering, small-angle X-ray scattering, and viscometry with 0.05 M aqueous NaCl at 25 °C as the solvent. The (total) weight-average molecular weight M_w ranges from 2.2 × 10⁴ to 7.1 × 10⁶. The radii of gyration, scattering functions, and intrinsic viscosities determined as functions of M_w are analyzed in terms of the cylindrical wormlike chain model. The estimated Kuhn segment length of about 120 nm is much larger than that (16 nm) for the polystyrene polymacromonomer with the equivalent side-chain length in toluene, a good solvent, while the chain thickness (5.5 nm) is comparable to or only slightly larger than that (5 nm) of the nonionic polymer. It is thus concluded that the electrostatic repulsion between side chains significantly stiffens the main chain of the polyelectrolyte brush.     

All solid-state polymer electrolytes prepared from a hyper-branched graft polymer using atom transfer radical polymerization

We propose an all solid-state (liquid free) polymer electrolyte (SPE) prepared from a hyper-branched graft copolymer. The graft copolymer consisting of a poly(methyl methacrylate) main chain and poly(ethylene glycol) methyl ether methacrylate side chains was synthesized by atom transfer radical polymerization changing the average chain distance between side chains, side chain length and branched chain length of the proposed structure of the graft copolymer. The ionic conductivity of the SPEs increases with increasing the side chain length, branched chain length and/or average distance between the side chains. The ionic conductivity of the SPE prepared from POEM₉ whose POEM content = 51 wt% shows 2 × 10⁻⁵ S/cm at 30 °C. The tensile strength of the SPEs decreases with increases the side chain length, branched chain length and/or average distance between the side chains. These results indicate that a SPE prepared from the hyper-branched graft copolymer has potential to be applied to an all-solid polymer electrolyte.     

Sulfur-containing hyperbranched polymeric photoinitiator end-capped with benzophenone and tertiary amine moieties prepared via simultaneous double thiol-ene click reactions used for UV curing coatings

A series of sulfur-containing hyperbranched polymeric photoinitiators end-capped with benzophenone (BP) and tertiary amine moieties (B/A-HPIs) were synthesized via the simultaneous double thiol-ene click reactions of thiolated hyperbranched polymer with both dimethylaminoethyl acrylate and 3-(4-benzoylphenoxy)propyl acrylate. The molecular structures were characterized by ¹H NMR and FT-IR spectroscopy. From the UV-vis spectra, B/A-HPIs showed the stronger n-π* absorption at ∼340 nm with a higher molar extinction coefficients of 371 L mol⁻¹ cm⁻¹ than 148 L mol⁻¹ cm⁻¹ of BP, and an obvious red shift of π-π* absorption from ∼250 nm of BP to ∼280 nm. According to the photo-DSC study, the photopolymerization rate of 1,6-hexanediol diacrylate initiated by 5 wt% B/A-HPI was twice higher than that by BP. The DMTA results showed the good miscibility of B/A-HPIs with acrylate resins and high crosslinking density of cured films.     

Synthesis of densely grafted copolymers by nitroxide-mediated radical polymerization of styrene using poly(phenylacetylene)s as a macroinitiator

Poly(phenylacetylene)s carrying alkoxyamine moieties in the side chain were prepared by Rh-catalyzed homopolymerization of 1-(4-ethynylphenyl)-1-(2,2,6,6-tetramethyl-1-piperidinyloxyl)ethane (1) and random copolymerization of 1 and 4-methoxy-1-ethynylbenzene (2a) or 4-decyloxy-1-ethynylbenzene (2b). ¹H NMR spectra showed that the poly(phenylacetylene)s adopted a cis-transoid structure. Using the poly(phenylacetylene)s as the macroinitiator the nitroxide-mediated radical polymerization of styrene (St) was carried out at 120 °C to yield densely grafted copolymers as a light yellow powder. The side chain lengths of the graft copolymers were determined by both ¹H NMR and conversion of St, which agreed with each other. The SEC profiles of the graft copolymers were unimodal at low conversions but were not unimodal at high conversion: a shoulder was observed in the high molecular=weight region and a small peak was observed in the low molecular=weight region. ¹H NMR measurements of the graft copolymers indicated that the copolymers adopted a trans-transoid structure, revealing that isomerization from cis-transoid to trans-transoid forms took place during the polymerization of St at 120 °C.     

Spectroscopic analysis of poly(bisphenol A carbonate) using high resolution C and H NMR

Quantitative structural and end-group analysis of poly(bisphenol A carbonate) (BPA-PC) was carried out and number average molecular weights (M_n) were determined using 125.76 MHz ¹³C and 500.13 MHz ¹H nuclear magnetic resonance (NMR) spectroscopy. BPA-PC with a wide range of end-group ratios (0.26-2.83) and number average molecular weights (1500-9000 g/mol) was synthesized using melt transesterification by changing the initial monomer (bisphenol A and diphenyl carbonate) ratios and reaction conditions. Results of the NMR analysis for the melt-polymerized samples were compared with those of a commercial BPA-PC with a M_n of 16,000 g/mol. It was demonstrated that NMR spectroscopy is a very selective and accurate method not only for quantification of both phenolic and phenyl chain end-groups but also in the structural analysis of main chain groups. Extremely small concentrations of end-groups (∼0.02 per repeating unit) were analyzed. In addition, NMR spectroscopy was found to be an excellent tool for detecting residual monomer and the presence of the reaction byproduct (phenol). The molecular weights that were determined using NMR end-group quantification agreed well with the molecular weights measured by gel-permeation chromatography (GPC).     

Synthesis and pH-dependent micellization of 2-(diisopropylamino)ethyl methacrylate based amphiphilic diblock copolymers via RAFT polymerization

The polymerization of 2-(diisopropylamino)ethyl methacrylate (DPA) by RAFT mechanism in the presence of 4-cyanopentanoic acid dithiobenzoate in 1,4-dioxane was studied. The DPA homopolymer was employed as a macro chain transfer agent to synthesize pH-sensitive amphiphilic block copolymers using poly(ethylene glycol) methyl ether methacrylate (PEGMA) as the hydrophilic block. ¹H NMR and GPC measurements confirmed the successful synthesis of these copolymers. Potentiometric titrations and fluorescence experiments proved that the copolymers underwent a sharp transition from unimers to micelles at a pH of ∼6.7 in phosphate buffered saline solutions. It was found that the hydrophilic/hydrophobic balance of these block copolymers had no apparent effect on their pH-induced micellization behaviors. The DLS investigation revealed that the micelles have a mean hydrodynamic diameter below 60 nm with a narrow size distribution.     

Microstructure of Triton X-100/poly (ethylene glycol) complex investigated by fluorescence resonance energy transfer

The microstructure of Triton X-100 (TX-100)/poly (ethylene glycol) (PEG) complex has been investigated by fluorescence resonance energy transfer (FRET), dynamic light scatter (DLS), freeze-fractured transmission electron microscopy (FF-TEM) and ¹H NMR technology. The nonionic surfactant TX-100 and pyrene are employed as energy donor and acceptor respectively, and the average distance between them is calculated quantitatively in the systems of TX-100/PEG with different molecular weights (MW). The results of FRET study indicate that the presence of PEG leads to the separation of donor and acceptor in TX-100 micelle, suggesting that PEG chains insert into TX-100 micelles making the microstructure of PEG-bound TX-100 aggregates looser than that of free micelles, which is independent of the MW of PEG. However, FF-TEM, DLS and ¹H NMR studies show that the morphology of TX-100/PEG complex depends on the MW of the polymer: PEG with shorter chain (MW < 2000 Da) insert into and wrap around TX-100 micelles and form sphere-like complex, while that with longer chain (MW > 2000 Da) would interact with numbers of TX-100 micelles and form coral-shaped clusters. In addition, the effects of temperature and alcohol on the microstructure of TX-100/PEG complex are studied.     

Green polymer-light-emitting-diodes based on polyfluorenes containing N-aryl-1,8-naphthalimide and 1,8-naphthoilene-arylimidazole derivatives as color tuner

A novel series of green light emitting single polymers were prepared by end-capping of N-aryl-1,8-naphthalimide and 1,8-naphthoilenearylimidazole derivatives into polyfluorene. The electroluminescence (EL) spectra of polymers (P1 ∼ P5) exhibit greenish-blue, bluish-green, pure green, and yellowish-green emission (λ_max = 465 nm, 490 nm, 500 nm, and 545 nm, respectively) from compounds (M1 ∼ M5). It was found that by the introduction of a small amount of compounds (M1 ∼ M5) (5 mol-%) into polyfluorene, the emission color can be tuned from the blue to green region. The color tuning was found to have gone through charge trapping and Förster energy transfer. The device of P4 emits pure green light with Commission Internationale de l'Eclairage (CIE) coordinates of (0.20, 0.41), and exhibits a maximum brightness of 11500 cd/m² at 12 V with a structure of indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid) [PEDOT:PSS]/PVK/emission layer/Ca/Ag. The device of P5 emits yellowish green light with Commission Internationale de l'Eclairage (CIE) coordinates of (0.36, 0.56), and exhibits a maximum brightness of 6534 cd/m² at 17 V.     

Single molecule force spectroscopy of smart poly(ferrocenylsilane) macromolecules: Towards highly controlled redox-driven single chain motors

We investigated various stimuli-responsive poly(ferrocenylsilane) (PFS) polymers as model systems for the realization of molecular motors powered by a redox process. Covalently end-grafted PFS on gold, as well as PFS homopolymers and block copolymers in ultrathin films, were studied by AFM-based single molecule force spectroscopy (SMFS). Surface confined PFS macromolecules were chemically oxidized by addition of tetracyanoethylene or were completely and reversibly oxidized (and reduced) in situ by applying an electrochemical potential. Chemical oxidation was successful only for the block copolymers. The entropic elasticity of neutral PFS chains (Kuhn length I_K∼0.40 nm) was found to be larger than that of oxidized PFS chains (I_K∼0.65 nm) in the lower force regime. The elasticities could be reversibly controlled in situ by adjusting the applied potential in electrochemical SMFS experiments. For a single PFS macromolecule (DP=80) operating cycle, a work output and an efficiency of 3.4×10⁻¹⁹ J and ∼5%, respectively, were estimated based on the single chain experimental data.     

The spatial uniformity and electromechanical stability of transparent, conductive films of single walled nanotubes

We have prepared thin films of arc discharge single walled nanotubes by vacuum filtration. For film thicknesses greater than 40 nm, the films are of high optical quality; the optical transmission varies by <2% over the film area when measured with a spatial resolution of 4 μm. However, the films become spatially non-uniform for film thickness below 40 nm. The in-plane DC conductivity correlates with the uniformity, increasing from ∼3800 S/m for a 10 nm thick film to ∼2-2.5 × 10⁵ S/m for films of thickness >40 nm. Conductive atomic force microscopy maps show reasonably uniform current flow out of the plane of the film. For all thicknesses, the optical transmittance scales with film thickness as expected for a thin conducting film with optical conductivity of 1.7 × 10⁴ S/m (λ = 550 nm). For films with t > 40 nm the ratio of DC to optical conductivity was σ_DC/σ_Op = 13.0, leading to values of transmittance and sheet resistance such as T = 80% and R_s = 110 Ω/□ for the t = 40 nm film. Electromechanically, these films were very stable showing conductivity changes of <5% and <2% when cycled over 2000 times in compression and tension respectively.     

Synthesis, characterization and optical properties of cross-linkable poly(phthalazinone ether ketone sulfone)

Cross-linkable poly(phthalazinone ether ketone sulfone) bearing tetrafluorostyrene groups (PPEKS-FSt) has been prepared by copolycondensation reaction for optical waveguide applications. The resulting amorphous polymer exhibits good solubility in some common polar organic solvents (e.g., N,N′-dimethylacetamide, N-methyl-2-pyrrolidinone, chloroform) at room temperature, and can be easily spin-coated into thin films with good optical quality. The glass transition temperature (T_g) and the temperature of 1% weight loss (1% T_d) are 261 °C and 494 °C, respectively, which could be further increased by 31 °C and 14 °C upon thermal cross-linking. The cross-linked polymer thin films exhibit high refractive index (∼1.65, TE mode), high thermo-optic coefficient value (dn/dT) (−1.455 × 10⁻⁴/°C, TE mode), low optical loss (less than 0.24 dB/cm at 1310 nm) and relatively low birefringence (∼0.007).     

Synthesis, isothermal crystallization and micellization of mPEG-PCL diblock copolymers catalyzed by yttrium complex

Amphiphilic biodegradable mPEG-PCL diblock copolymers have been synthesized using rare earth catalyst: yttrium tris(2,6-di-tert-butyl-4-methylphenolate) [Y(DBMP)₃] in the presence of monomethoxy poly(ethylene glycol) (mPEG, M_n = 5000) as macro-initiator. The diblock architecture of the copolymers was thoroughly characterized by ¹H NMR, ¹³C NMR and SEC. The molecular weights of mPEG-PCLs can be well controlled by adjusting the feeding molar ratio of ?-CL to mPEG. Thermal and crystallization behaviors of the diblock copolymers were investigated by DSC and POM (polarized optical microscope). The crystallization property of mPEG-PCL block copolymers depends on the length of PCL blocks. As the molecular weight of PCL block increased, the crystallization ability of mPEG block was visibly restrained. Aqueous micelles were prepared by dialysis method. The critical micelle concentration of the copolymers, which was determined to be 0.9-6.9 mg/L by fluorescence technique, increased with the decreasing of PCL block length. The particle sizes determined by DLS were 30-80 nm increasing with the PCL block length. TEM images showed that these micelles were regularly spherical in shape.     

The structures of poly(oxyethylene)s having sulfone groups in the side chains

The structures of (OCH₂CHR) with R=CH₂S(CH₂)₆SO₂(CH₂)_MH (ATP-M; M=5,7,9) or R=CH₂SO₂(CH₂)₆SO₂(CH₂)_MH (ASP-M; M=5,7,9) were studied using X-ray diffraction and differential scanning calorimetry. The X-ray patterns of all ATPs and ASPs studied show a series of ordered reflections in the small angle region and a sharp wide angle reflection at d=∼4.4 Å, characteristic of a smectic phase. The smectic layer thickness corresponds to twice the most extended side chain length and linearly increases as the side chain length increases with a slope of ∼2.3 Å per methylene spacer. This indicates that all ASPs and ATPs studied have a double layer structure with side chains normal to the main chain and probably an all-trans conformation of the side chains. The correlation lengths measured from the wide angle reflections are in the range of 80±10 Å for all the polymers except for ASP-5 (∼40 Å). These values indicate that quasi-long-range order exists in the smectic layers whose structures can be defined as smectic B (S_B). The d-spacing of the wide angle reflection, 4.4 Å, suggests that paraffinic side chain crystallization does not occur and that the smectic mesophase develops through dipole-dipole interactions of sulfone groups in the side chains. During heating, ATP-5 shows recrystallization after the first melting. The structure produced during recrystallization has a similar smectic structure but with more dense packing between side chains than before the first melting. In the case of ASP-9, a smectic to smectic transition was observed at ∼110°C prior to the isotropic temperature at ∼150°C. Both the correlation length (from the wide angle reflection) and the layer thickness decreased from ∼80 to ∼30 Å and from 46 to 40 Å at this transition, respectively, indicating that the order in the smectic layers is lost and the S_B structure has become a less ordered S_A structure at this transition.     

Effects of the oxygen pressure on the crystalline orientation and strains of YSZ thin films prepared by E-beam PVD

Yttria−stabilized zirconia, YSZ, thin films were prepared by E-beam physical vapor deposition (PVD) at 200 °C under oxygen pressure of 1 × 10⁻³∼1 × 10⁻⁵ Torr. Observations by Field Emission Scanning Electron Microscope (FESEM) proved that different oxygen pressures influenced the thickness of interfacial SiO_x layer formed between the YSZ thin films and Si(100)-substrate. X-ray diffraction (XRD) patterns were used to determine the crystalline structure and calculate the surface grain size of deposited YSZ thin films. XRD patterns also showed that the peaks corresponding to planes (111), (200), (220), and (311) were found and the YSZ thin films revealed the fluorite structure. At lower oxygen pressure (1 × 10⁻⁵∼1 × 10⁻⁴ Torr) YSZ thin films revealed the (111) preferred orientation and at higher oxygen pressure (5 × 10⁻⁴∼1 × 10⁻³ Torr) YSZ thin films revealed the (200) preferred orientation. The effects of oxygen pressure on the lattice constants and the internal strains of YSZ thin films were also investigated.     

Bimodal, templated mesoporous carbons for capacitor applications

Several high capacitance ordered mesoporous carbon (OMC) materials, containing a bimodal pore distribution, were synthesized directly using hexagonal mesoporous silicas (HMS) as the template material. The HMS templates were formed using amine surfactants (C_nH_2n+1NH₂) with hydrophobic chain lengths containing 8-16 carbons (n = 8-16). These HMS structures were found to have an interconnected wormhole structure, high textural mesoporosity, a surface area ranging from 910 to 1370 m²/g, and a total pore volume of 1.09-1.83 cm³/g. Also, evidence for a change in structure from hexagonally ordered to layered (for surfactants of chain length with n > 12) was found. The resulting OMCs, formed using sucrose as the carbon precursor, contain bimodal pores 1.6-1.8 and 3.3-3.9 nm in diameter and have a very high surface area (980-1650 m²/g). The OMCs were evaluated as electrode materials for electrochemical capacitors using cyclic voltammetry in 0.5 M H₂SO₄ solution, giving a tunable gravimetric capacitance that increased linearly with BET area (and surfactant chain length), up to 260 F/g, among the highest yet reported for ordered carbon formed from an HMS templated precursor. All OMCs studied in this work displayed a specific capacitance of ∼0.15 F/m².     

High lithium conductivities in weakly-ionophilic low-dimensional block copolymer electrolytes

The structure of amphiphilic low-dimensional copolymer electrolytes I of similar overall composition but prepared by different synthetic procedures X and Y are described. I are copolymers of poly[2,5,8,11,14-pentaoxapentadecamethylene(5-alkyloxy-1,3-phenylene)] (CmO5) and poly[2,-oxatrimethylene(5-alkyloxy-1,3-phenylene)] (CmO1) where the alkyl side chains having m carbons are hexadecyl or mixed dodecyl/octadecyl (50/50). ¹H NMR shows that the copolymers have 50% (m = 16) or only 18 and 13% of CmO5 units and DSC indicates that the copolymers have ‘block’ sequencing of CmO1 and CmO5 segments. Molecular dynamics modelling indicates that in CmO5 Li⁺ and BF₄⁻ ions are separated by Li⁺ encapsulation in tetraethoxy segments but in ionophobic CmO1 units the salt is mostly present as neutral aggregates decoupled from the polymer. Conductivities of these microphase-separated mixtures with salt-bridge amphiphilic polyethers II and III of each system are similar. They have low temperature dependence over the range 20 °C to 110 °C at ∼10⁻³ S cm⁻¹. ⁷Li NMR linewidth measurements confirm high lithium mobilities at −20 °C. A conduction mechanism is proposed whereby Li⁺ hopping takes place along rows of decoupled aggregates (dimers/quadrupoles) within an essentially block copolymer structure. Subambient measurements to −10 °C gave a conductivity of 4 × 10⁻⁵ S cm⁻¹.     

Cross-linked latex particles grafted with polyisoprene as model rubber-compatible fillers

Model filler particles were obtained by grafting polyisoprene (PIP) chains onto spherical latex particles of polystyrene cross-linked with 12 mol% divinylbenzene. These particles, with a narrow size distribution and a diameter of ca. 400 nm, were synthesized by emulsifier-free starved-feed emulsion polymerization. Acetyl coupling sites were introduced randomly at either low (5 mol%) or high (30 mol%) target substitution levels on the latex particles by Friedel-Crafts acylation with acetyl chloride and AlCl₃ in nitrobenzene. ‘Living’ polyisoprenyllithium chains, generated from isoprene and sec-butyllithium (sec-BuLi), were then coupled with the acetylated particles. The PIP side chains had a high 1,4-polyisoprene microstructure content and a number-average molecular weight (M_n) of either 1.5 × 10³ (1.5 K), 5 × 10³ (5 K), or 3 × 10⁴ (30 K). The PIP content of the grafted particles was determined from the yield of isolated particles and by ¹H NMR spectroscopy analysis. The grafted latex particles were blended in solution with linear polyisoprene (M_n = 3.95 × 10⁵, 395 K). The influence of the filler-matrix interactions on the rheological behavior of the blends was determined by dynamic mechanical analysis for the different filler blends. Increases in complex viscosity and storage modulus, and decreased damping factors were observed in all cases relatively to the pure matrix polymer. The enhancements, decreasing in the order 30 mol% > 5 mol% acetylation, and with the grafted PIP chain length as 30 K > 5 K ≈ 1.5 K, are deemed to reflect the extent of interactions between the filler particles and the polymer matrix.