OH Functionality Research Articles

Preparation of 4-Allenyloxazolines from (Z)-2-En-4-yn-1-ol via Propargyl/Allenyl Isomerization.

A novel method for the preparation of 4-allenyl-oxazolines 2 is described via the reaction of 2-en-4-yn-1-ols 1 with trichloroacetonitrile in the presence of DBU. Reaction proceeds through the nucleophilic attack of OH functionality in 1 to CCl3CN followed by cyclization, propargyl/allene isomerization, and protonation. In this investigation, it is noticed that propargyl/allene isomerization is sensitive to the substituents.

Biradicals based on PROXYL containing building blocks for efficient dynamic nuclear polarization in biotolerant media

A versatile strategy for synthesizing tailored peptide based biradicals is presented. By labeling the protected amino acid hydroxyproline with PROXYL via the OH functionality and using this building block in solid phase peptide synthesis (SPPS), the obtained peptides become polarization agents for DNP enhanced solid-state NMR in biotolerant media. To analyze the effect of the radical position on the enhancement factor, three different biradicals are synthesized. The PROXYL spin-label is inserted in a collagen inspired artificial peptide sequence by binding through the OH group of the hydroxyproline moieties at specific position in the chain. This labeling strategy is universally applicable for any hydroxyproline position in a peptide sequence since solid-phase peptide synthesis is used to insert the building block. High performance liquid chromatography (HPLC) and mass spectrometry (MS) analyses show the successful introduction of the spin label in the peptide chain and electron paramagnetic resonance (EPR) spectroscopy confirms its activity. Dynamic nuclear polarization (DNP) enhanced solid-state nuclear magnetic resonance (NMR) experiments performed on frozen aqueous glycerol-d8 solutions containing these peptide radicals show significantly higher enhancement factors of up to 45 in 1H→13C cross polarization magic angle spinning (CP MAS) experiments compared to an analogous mono-radical peptide including this building block (ε ≈ 14). Compared to commercial biradicals such as AMUPol for which enhancement factors > 100 have been obtained in the past and which have been optimized in their structure, the obtained enhancement up to 45 for our biradicals presents a significant progress in radical design.

Chiral NHC Ligands for Enantioselective Gold(I) Catalysis Under Aerobic Conditions: the Importance of Conformational Flexibility and Steric Hindrance of NHC Ligand on Reactivity.

Gold(I) catalysis has been recognized as a valuable tool for the unique transformation of multiple carbon-carbon bonds. Enantioselective π-catalysis based on gold(I) complexes is, however, still underdeveloped due to lack of privileged ligands. Herein, we present an accessible method to a new family of stable yet catalytically active chiral NHC-Au(I)-Cl complexes. The key to preserving a simultaneous fine balance between reactivity and stability in this newly developed family appears to be sterically hindered, but conformationally flexible NHC ligands. These could be easily accessed on a multigram scale by merging sterically hindered anilines with commercially available amino alcohols and amines via a four-steps synthetic sequence without the need for chromatographic purification. Further investigations of the catalytic activity of NHC-Au-Cl complexes identified the OH functionality incorporated into the NHC core as crucial for the level of enantioselectivity as well as the TsO- anion responsible for the activation of NHC-Au(I)-Cl. Finally, NMR studies and X-ray investigations revealed for the first time that the widely accepted ion metathesis (NHC-Au-Cl to NHC-Au-OSO2 R) responsible for the activation of NHC-Au-Cl complexes does not take place (or it is very slow) in commonly used MeNO2 in contrast to DCM.

Sustainable polyurethane coatings based on functional Camelina oil-based polyols

Polyurethane (PU) coatings have garnered considerable attention across diverse applications and industries, owing to their versatile physiochemical attributes. Despite their widespread use, the environmental implications associated with their carbon footprint have raised concerns in recent years. To address this issue, we explored the potential of Camelina oil as a base chemical for synthesizing polyesteramide polyols as a viable alternative to petrochemical-based materials. Consequently, we formulated biocarbon-rich polyurethane coatings using the synthesized polyols. Initially, we synthesized a fatty amide intermediate through a transamidation reaction, involving the interaction of diethanolamine and triglyceride. Subsequently, we produced three distinct polyesteramide polyols using citric acid, itaconic acid, and phthalic acid. To confirm the formation of ester and amide linkages, we employed various structural analyses, including Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared (FTIR) spectroscopy, on the Camelina-oil-derived polyols. Furthermore, we utilized quantitative techniques such as titration to ascertain hydroxyl number, acid number, and amine value. Our structural analyses corroborated the establishment of ester linkage and the incorporation of OH functionality in Camelina oil, while titration results indicated a remarkable 1200 % surge in hydroxyl value. We subsequently employed the three polyesteramide polyols to fabricate polyurethane coatings, subjecting them to a battery of tests. The resultant biobased coatings were assessed using Dynamic Mechanical Analysis (DMA), Thermo-Gravimetric Analysis (TGA), and an array of surface characteristics such as gloss, hardness, impact resistance, water contact angle, and saline resistance. All tested samples exhibited satisfactory thermal stability, with the biocarbon content of the final PU coatings measuring at least 61.6 %. Moreover, our study demonstrates that the derived polyurethane coatings hold promise for non-wet applications, particularly in the realm of interior coatings.

Self-Assembly, In Vitro Gene Transfection, and Antimicrobial Activity of Biodegradable Cationic Bolaamphiphiles.

Bolaamphiphiles or bolaforms have drawn particular interest in drug and gene delivery, and studies of bolaforms have been growing continuously. Bolaforms, due to their unique structure, exhibit specific self-assembly behavior in water. The present work aims to develop biodegradable cationic bolaforms with a better gene transfection ability. In this work, a novel cationic bolaform (Bola-1) with head groups bearing hydroxyl (OH) functionality was designed and synthesized to investigate self-assembly and gene transfection efficiency. The self-assembly behavior of Bola-1 in water was compared with that of the hydrochloride salt (Bola-2) of its precursor molecule to investigate the effect of the -OH functionality on their solution properties. Several techniques, including surface tension, electrical conductivity, fluorescence probe, calorimetry, dynamic light scattering, and atomic force microscopy, were employed for the physicochemical characterization of Bola-1 and Bola-2. Despite the presence of polar urea groups in the spacer chain, both bolaforms were found to form spherical or elongated micelles above a relatively low critical aggregation concentration (CAC). The presence of the OH group was found to significantly affect the CAC value. The results of calorimetric measurements suggested a thermodynamically favorable aggregate formation in salt-free water. Despite stronger binding efficiency with calf thymus DNA, in vitro gene transfection studies performed using adherent cell Hek 293 suggested that both Bola-1 and Bola-2 have gene transfection efficiency comparable to that of turbofectamine standard. Both bolaforms were found to exhibit significant in vitro cytotoxicity at higher concentrations. Also, the bolaforms showed beneficial antibacterial activity at higher concentrations.

Mixed Organic Counterion Strategy Modulates the Self-Assembly of Polyoxometalate Hybrids into Toroids and Affects Their Photochromic and Photocatalytic Properties.

A series of five mixed-counterion polyoxometalate (POM) hybrids 1-5 have been developed starting from the [SiW12O40]4- cluster and two different aryl sulfonium counterions (ASCIs), (4-hydroxyphenyl)dimethylsulfonium (HPDS) and (4-formylphenyl)dimethylsulfonium (FPDS), bearing different functional groups -OH and -CHO, respectively. The HPDS/FPDS counterion ratio in hybrids 1-5 varied as 4:0 (1), 3:1 (2), 2:2 (3), 1:3 (4), and 0:4 (5), and it resulted in a morphological transition of the self-assembly of these hybrids. Hybrid 1 exhibited spherical self-assembly, while hybrid 5 exhibited large toroidal self-assembly predominantly. The hybrids 2-4 gave a mixture of spherical, dimpled spherical, and toroidal self-assemblies in varying amounts, indicating a gradual transition of self-assembly from spherical to toroidal as the percentage of FPDS increases in the system. A plausible explanation for the differences in the self-assembly properties of these hybrids has been proposed based on the differences in the H-bonding interactions of the two counterions with the dispersion medium. The HPDS and FPDS counterions exhibited different HOMO-LUMO gaps, and their varying percentages in hybrids 1-5 led to differences in optical band gaps and photochromic activities. Hybrid 2 showed the lowest band gap value and the best photochromic activity (t1/2 = 0.72 min) in the series. The influence of the mixed-counterion strategy in catalysis has been demonstrated by evaluating the photocatalytic activity of these hybrids toward rhodamine B dye degradation. The hybrid 4, exhibiting stable toroidal self-assembly, showed the best catalytic activity in the series, probably due to a combination of reasons such as the enhanced surface area due to toroid formation and also the presence of H-bonding -OH functionality on the counterion. Therefore, the present study suggests a new method for altering the self-assembly and the materials and catalytic properties of POM hybrids through a mixed-counterion strategy.

Corrosion-resistant polyurethane coatings from structure-homogenized biorefinery lignin through fractionation and oxypropylation

Using lignin for polyurethane (PU) synthesis is challenging because of its heterogeneous structure, i.e., broad molecule weight (MW) distribution and diverse hydroxyl (OH) functionality. This complexity influences the crosslinking reaction between lignin and isocyanate and affects the quality of PU products. Here, we propose a two-step strategy for lignin structure homogenization by lowering its MW, while narrowing the MW distribution (step 1), and achieving uniform OH functionality (step 2). Step 1 involves a bioethanol fractionation process, yielding fractionated lignin with one order lower MW than the raw lignin while exhibiting better processability for the subsequent process. Step 2 is performed by an oxyalkylation process using fractionated lignin that converts phenolic and carboxylic OHs to aliphatic OHs. As a result, we obtained structure-homogenized lignin with good compatibility and crosslinking with hexamethylene diisocyanate for PU coating synthesis. Moreover, PU coatings prepared from structure-homogenized lignin display a defect-free microscopic structure and show better corrosion resistance than coatings fabricated from its raw lignin alternative. Overall, the structure homogenization process is a beneficial way of using lignin as biopolyol in PU synthesis toward the application-oriented design of corrosion-resistant lignin-based PU coatings.

Friedel-Crafts Acylation of Aminocarboxylic Acids in Strong Brønsted Acid Promoted by Lewis Base P4O10.

The amino group in aminocarboxylic acids is sufficiently basic to be protonated in strong acids, and consequently, ionization of the carboxylic acid to an acylium ion is blocked due to charge-charge repulsion. Thus, acylation of aromatic compounds is significantly retarded in Friedel-Craft type reactions. We found that Friedel-Crafts acylation with aminocarboxylic acids can proceed smoothly even in a strong Brønsted acid (triflic acid, TfOH) if the Lewis base P4O10 is added. Here we describe the Friedel-Crafts acylation reactions of anthranilic acid and α- to δ-aminocarboxylic acids with benzene derivatives in the presence of P4O10. Non-amino-containing carboxylic acids as well as N-containing heteroaromatic carboxylic acids are available, and α-amino acids can be directly utilized without any protective group. Most substrates afford acylation products in high yields, although some epimerization/racemization may occur. Density functional theory (DFT) calculations suggested that P4O10 neutralizes the protonated amine, converting the N-H covalent bond to a N-hydrogen bond and allowing the carboxylic acid OH functionality to serve as a good leaving group.

Highly Efficient Removal of Rhodamine B Dye Using Nanocomposites Made from Cotton Seed Oil-Based Polyurethane and Silylated Nanocellulose

Biobased polyurethane nanocellulose nanocomposites were synthesized from cottonseed oil as the source for the biopolyol. The prepared composites were used to study the adsorption of Rhodamine B dye from water. Low functional polyol was derived from cottonseed oil using one-pot synthesis method. Nanocellulose was derived from pineapple leaves and then it was surface-functionalized via silylation. In-situ polymerization technique was used to incorporate the silylated nanocellulose into the polyurethane matrix. The prepared polyol from cottonseed oil was found to have an OH functionality of 2 which was confirmed by Fourier transform infrared spectroscopy (FT-IR) and Nuclear magnetic resonance (NMR) spectroscopy. Low functionality of polyol is the key factor in achieving flexible porous polyurethane. The silylated nanocellulose, polyurethane, and composites were characterized by FT-IR, X-ray diffraction analysis (XRD), and Scanning electron microscopy (SEM). The adsorption parameters were optimized using the Taguchi methodology and the adsorption efficiency was determined by carrying out adsorption at optimized parameters (5 wt% loading of silylated nanocellulose, pH 9, and temperature of 30 °C) for 8 h. Studies showed that the prepared composite has a high adsorption efficiency of 597 mg/g of silylated nanocellulose towards Rh-B.

Impact of enzymatically synthesized aliphatic–aromatic polyesters with increased hydroxyl group content on coating properties

AbstractNowadays, coating systems have to fulfill a wide range of requirements. In addition to mechanical properties such as hardness and elasticity, resistance and weatherability, specifically corrosion or chemical resistance are also important. Increasing attention is also being paid to points such as the use of sustainable reactants or the energy optimization of synthesis processes.1 The use of enzymes in the synthetic processes offers two main advantages: firstly, reaction temperatures can be significantly reduced, for example in the production of polyesters, and as a result and a major advantage, certain functional groups can be selectively retained during the reaction.2,3 Thus, for example, aromatic hydroxyl groups can be obtained, while aliphatic groups are esterified.4,5 This allows the preparation of polyesters that do not only have terminal OH groups, but hydroxyl groups within the chain that can act as additional crosslinking points during network formation or as adhesion-promoting groups.6,7 In this work, the influence of such an aliphatic–aromatic polyester, produced enzymatically at low temperatures, on the coating properties is investigated when using different hardener components. Coating formulations were created, and the required OH functionality and the hydroxyl number of the enzymatic polyester have been calculated by using two different, independent methods. Besides the development of guide formulations, the unique mechanical properties of coatings based on the enzymatic polyester were studied. In addition to comparative analysis of network densities, the coatings were also investigated by IR spectroscopy in order to assess the network formation reaction spectroscopically. It can be shown that additional OH groups in the polyester chain increase the network density, but this is not at the expense of elasticity. Thus, enzymatically produced polyesters combine the advantages of low reaction temperatures during production with a unique property profile due to aliphatic and aromatic moieties as well as the partial preservation of OH groups within the chain.

Investigating the structure-activity relationship of marine polycyclic batzelladine alkaloids as promising inhibitors for SARS-CoV-2 main protease (Mpro)

Over a span of two years ago, since the emergence of the first case of the novel coronavirus (SARS-CoV-2) in China, the pandemic has crossed borders causing serious health emergencies, immense economic crisis and impacting the daily life worldwide. Despite the discovery of numerous forms of precautionary vaccines along with other recently approved orally available drugs, yet effective antiviral therapeutics are necessarily needed to hunt this virus and its variants. Historically, naturally occurring chemicals have always been considered the primary source of beneficial medications. Considering the SARS-CoV-2 main protease (Mpro) as the duplicate key element of the viral cycle and its main target, in this paper, an extensive virtual screening for a focused chemical library of 15 batzelladine marine alkaloids, was virtually examined against SARS-CoV-2 main protease (Mpro) using an integrated set of modern computational tools including molecular docking (MDock), molecule dynamic (MD) simulations and structure-activity relationships (SARs) as well. The molecular docking predictions had disclosed four promising compounds including batzelladines H–I (8–9) and batzelladines F-G (6–7), respectively according to their prominent ligand-protein energy scores and relevant binding affinities with the (Mpro) pocket residues. The best two chemical hits, batzelladines H–I (8–9) were further investigated thermodynamically though studying their MD simulations at 100 ns, where they showed excellent stability within the accommodated (Mpro) pocket. Moreover, SARs studies imply the crucial roles of the fused tricyclic guanidinic moieties, its degree of unsaturation, position of the N–OH functionality and the length of the side chain as a spacer linking between two active sites, which disclosed fundamental structural and pharmacophoric features for efficient protein-ligand interaction. Such interesting findings are greatly highlighting further in vitro/vivo examinations regarding those marine natural products (MNPs) and their synthetic equivalents as promising antivirals.

WVI–OH functionality on polyoxometalates for water reduction to molecular hydrogen

When a polyoxometalate cluster surface is grafted with WVI–(OH)2 functionality, the surface-modified POM turns into an efficient & stable electrocatalyst for hydrogen evolution reaction by water reduction. We performed detailed kinetic studies for this electrocatalysis.

The Elusive Au(I)···H-O Hydrogen Bond: Experimental Verification.

Our long-standing interest in atypical bonding situations has recently led us to target complexes in which a metallobasic gold(I) center is hydrogen-bonded to a nearby OH functionality. Here, we report on the synthesis and characterization of two neutral gold(I) indazol-3-ylidene complexes bearing a carbinol or silanol group at the 4-position. As indicated by X-ray diffraction, 1H NMR spectroscopy, IR spectroscopy, and extensive computational modeling, the OH group of these derivatives is engaged in a bona fide Au···H-O interaction. In addition to shedding light on an elusive bonding situation, these results also indicate that increasing the acidity of the OH functionality is not necessarily beneficial to the stability of the Au(I)···H-O interaction.

Molecular-Level Photo-Orientation Insights into Macroscopic Photo-Induced Motion in Azobenzene-Containing Polymer Complexes.

As part of continuing efforts to deepen the understanding of photo-induced mass transport in azo-containing polymers, we compared the diffraction efficiency (DE) during surface-relief grating (SRG) inscription, photo-induced molecular orientation (<P2>), and thermal stability in two sets of supramolecular azopolymer complexes, namely, hydrogen-bonded (H-bonded) and ionically bonded (i-bonded) complexes, both as a function of the polymer degree of polymerization (DP). To that end, poly(4-vinylpyridine) (P4VP) polymers with DPs of 41, 480, and 1900 were H-bonded at an equimolar ratio with 4-hydroxy-4'-dimethylaminoazobenzene (azoOH), and the fully quaternized derivatives of the three P4VPs (P4VPMe) were i-bonded via ion exchange to sodium 4-[(4-dimethylamino)-phenylazo]benzene sulfonate (azoSO3), also known as methyl orange, where the OH functionality of azoOH is replaced by a sulfonate group. The i-bonded complexes show much better DE performances and <P2> levels than those of H-bonded complexes, which we relate to the liquid crystal structure of the former complexes. Fitting the <P2> curves by a biexponential equation leads to two parameters associated with a fast trans-cis or angular hole burning (AHB) process and a slow angular redistribution (AR) process of the azo, respectively. It is found that AHB is predominant in the H-bonded complexes, whereas the AR contribution is much greater in the i-bonded complexes, assuring their superior SRG efficiency that is enabled by the anisotropic free volume created mainly by the AR process. In each set of complexes, the SRG efficiency is much better for the lowest DP complex, while the AR contribution is constant (and low) for the H-bonded complexes and increases roughly linearly with the decrease in DP for the i-bonded complexes. The latter difference might be related to the presence of entanglements in the complexes with DPs 480 and 1900, which slow down the macroscopic movement during SRG inscription but not the molecular-scale movement in photo-orientation.

DFT Analysis into the Calcium(II)-Catalyzed Coupling of Alcohols With Vinylboronic Acids: Cooperativity of Two Different Lewis Acids and Counterion Effects.

The mechanism of the calcium-catalyzed coupling of alcohols with vinylboronic acids has been analyzed by means of density functional theory computations. This study reveals that the calcium and boron Lewis acids associate to form a superelectrophile able to promote a pericyclic group transfer reaction with allyl alcohols. With other alcohols, the two Lewis acids act synergistically to activate the OH functionality and trigger a SNi reaction pathway. These two mechanisms are affected by the nature of the counterions, which has been rationalized by electronic and steric factors.

Effective changes in softwood cell walls, gas permeability and sound absorption capability of Larix kaempferi (larch) by steam explosion

ABSTRACT More interest in larch (Larix kaempferi) has been taken because of a greater focus on environmental properties. Steam explosion is an inexpensive and facile approach for the increasing rate of drying and durability of wood. A significant improvement in gas permeability and sound absorption coefficient of steam-exploded larch wood relative to the control wood is observed. It is due to structural changes in the cell wall that is proved by Fourier transform infrared spectroscopy, field emission scanning electron microscope, X-ray diffraction, and Energy-dispersive X-ray spectroscopy. The average increase in SAC of steam-exploded samples is 33.33% higher than the control samples at a wide range of frequency 250-6400 Hz due to the increasing air permeability (190.1%). Color of treated larch wood changed to black due to several chemical reactions in the cell wall and reduced of –OH functionality during the steam explosion. These findings summarized that steam explosion affects softwood cellulose cell walls, and the cross-section surface of larch wood could be considered for improving acoustic comfort in the building.

A metal-free Petasis reaction towards the synthesis of N-(α-substituted)alkyl sulfoximines/sulfonimidamides.

Herein, we disclose a metal-free novel approach for the synthesis of N-(α-substituted)alkyl sulfoximines/sulfonimidamides via one-pot multicomponent Petasis reactions of aryl boronic acids, ortho-hydroxyarylaldehydes and sulfoximines/sulfonimidamides in moderate to very good yields. The presence of two chiral centres provides a mixture of diastereomers almost in a 1 : 1 ratio, which are separated successfully in most of the cases. The -OH functionality of Petasis products is further utilized to derive heterocycles via O-allylation, followed by intramolecular Heck cyclization, proving the synthetic utility of the products.

Chemical and electrochemical corrosion studies of ricinus communis oil based poly(urethane-ricinoleamide) coatings

In view of the depletion and possible exhaust of fossil fuels in near future, enormous increase in the cost of petroleum products and production of volatile organic compounds (VOC) by synthetic polymers and their application, the proposed article reports the development of sustainable resource based high performance Ricinus communis oil (Castor Oil) [RC] poly(urethane-ricinoleamide) [PUR] corrosion resistant coatings on mild steel. The physico-mechanical properties were investigated using standard methods. The corrosion resistance performance of PUR coatings was evaluated by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in acid (3.5 wt% HCl) and alkaline (3.5 wt% NaOH) mediums. The weight loss measurement was also carried out under tap water (Cl- ion 63 mg/l; Conductivity 0.953 mS/A). Salt mist test (5 wt% NaCl) was performed on these coatings. The effect of additional –OH functionality of RC oil on the corrosion resistance performance of PUR coatings was also discussed. These investigations reveal that the PUR coatings provide protection to the mild steel by reducing the corrosion current density by 104 times as compare to bare MS. These coatings also exhibits higher corrosion resistance performance as compared to other reported sustainable resource based coating systems, hence show good potential for their commercial application.

Neutral 1D Perovskite-Type ABX3 Ferroelectrics with High Mechanical Energy Harvesting Performance

Organic–inorganic ABX3 hybrids with perovskite structures have drawn enormous attention owing to their intriguing chemical variability, structural tunability, and diversity of application-worthy properties. Herein, we report the synthesis of a new neutral ABX3 hybrid ferroelectric compound [Me3NCH2CH2OH]CdCl3 (1), which exhibits a 1D chain structure of edge-sharing CdCl5O octahedra that are connected to cationic [Me3NCH2CH2OH]+ units via its peripheral OH functionality. The single-crystal X-ray diffraction analysis of the compound at 363 K reveals the conversion of 1 to its coordination isomer 1′, in which the anionic chain consists of face-sharing CdCl6 octahedra and the cations are uncoordinated. The piezoresponsive force microscopy analysis performed on a single crystal of 1 confirms the existence of polarizable domains in it. The ferroelectric P–E loop measurements on 1 show a high remnant polarization value of 17.1 μC cm–2. Composite devices based on 1 and polydimethylsiloxane (PDMS) prepared with varying wt % compositions are examined for mechanical energy harvesting applications. The highest open-circuit voltage of 55.2 V and a maximum power density of 70.9 μW cm–2 at an optimal load of 4 MΩ were obtained for the 15 wt % 1–PDMS device. The harvested energy is shown to be effective for capacitor charging and light-emitting diode (LED) flash lighting applications.

Elucidating the Role of Interfacial Hydrogen Bonds on Glass Transition Temperature Change in a Poly(Vinyl Alcohol)/SiO2 Polymer-Nanocomposite by Noncovalent Interaction Characterization and Atomistic Molecular Dynamics Simulations.

A thorough experimental investigation of polymer-glass transition temperature (Tg ) is performed on poly(vinyl alcohol) (PVA) and fumed silica nanoparticle (SiNP) composite. This is done together with atomistic molecular dynamics simulations of PVA systems in contact with bare and fully hydroxylated silica. Experimentally, PVA-SiNP composites are prepared by simple solution casting from aqueous solutions followed by its characterization using Fourier-transform infrared spectroscopy (FTIR), dynamic mechanical analysis (DMA), and dynamic scanning calorimetry (DSC). Both theoretical and experimentally deduced Tg are correlated with the presence of hydrogen bonding interactions involving OH functionality present on the surface of SiNP and along PVA polymer backbone. Further deconvolution of FTIR data show that inter-molecular hydrogen bonding present between PVA and SiNP surface is directly responsible for the increase in Tg . SiNP filler and PVA matrix ratio is also optimized for a desired Tg increase. An optimal loading of SiNP exists, in order to yield the maximum Tg increase arising from the competition between hydrogen bonding and crowding effect of SiNP.