The Science of Adhesive Bonding and its Transfer to Technology

Author's Note

This article is based, in part, on a lecture given by the author on the occasion of his receipt of The Adhesion Society Award for Excellence in Adhesion Science, Sponsored by 3M at the Society's 14th Annual Meeting in Clearwater, Florida, U.S.A., February 1991. The author takes this opportunity to thank the Adhesion Society for the award and the 3M Corporation for its sponsorship. It is an honor to receive such a tribute from a society and a corporation that have done so much to advance the science and technology of adhesive bonding.     

Preparation of silicone containing 2,2,6,6-tetramethyl-4-piperidinol-based N-chloramine for antibacterial polyethylene via interpenetration in supercritical carbon dioxide

Functionalization of polyethylene (PE) with powerful biocides through a friendly and efficient procedure is necessary to obtain extended applications. A novel CO₂-philic 2,2,6,6-tetramethyl-4-piperidinol (TMP)-based N-chloramine silicone was synthesized via Pt-catalyzed silane alcoholysis between the Si H of poly(methylhydrosiloxane) and O H of TMP and followed by chlorination of amine N H originating from TMP to N Cl. The TMP-based N-chloramine silicone was interpenetrated into PE using supercritical carbon dioxide (scCO₂) as working solvent. It was shown that the thickness of the TMP-based N-chloramine silicone layer on PE can be easily controlled by the interpenetration pressure, reaching a maximum value of 70 nm at 28 mp. The synthetic procedures and the interpenetration results were characterized by Fourier transform infrared, scanning electron microscopy, and X-ray photoelectron spectroscopy. In contrast with pristine PE that did not show biocidal ability, the TMP-based N-chloramine silicone modified PE imparted powerful antibacterial abilities, exerting total kills of both Staphylococcus aureus and Escherichia coli of ~10⁷ cfu mL⁻¹ in 30 min. The biocidal functionality was durable toward washings, storage, and ultraviolet exposure and the recoverability of lost chlorines was good. The interpenetration in scCO₂ tactic provides an environmentally friendly and universal approach to functionalize inert substrates due to no needs of harmful solvent and chemical linkages with biocides. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47614.     

Microemulsion polymerization of siloxane with nonionic surfactants as emulsifiers

Polysiloxane nanolatices were prepared by the microemulsion polymerization of octamethylcyclotetrasiloxane (D₄) with nonionic polyoxyethylene alkyl ether and polyoxyethylene aryl ether as surfactants, ethylene glycol or aminoethanol as a cosurfactant, and potassium hydroxide or dipotassium dimethylsilanolate (I) as an initiator. The effect of the different initiators and the amount of cosurfactant on the microemulsion polymerization rate of D₄ was investigated. The initiator, potassium hydroxide, had a similar catalytic activity to I, and adding the cosurfactant changed a common siloxane emulsion to a microemulsion. At a same reaction conditions, the polymerization rate of D₄ with aminoethanol as a cosurfactant was much faster than that of ethylene glycol. The kinetics of this siloxane microemulsion polymerization was consistent with Morgen‐Kaler theory. The transparency value of the resultant polysiloxane nanolatex was more than 95% when the amount of ethylene glycol was more than 25% and the siloxane amount was about 30 wt % of the reaction mixture. A nanolatex of polydimethylsiloxane‐co‐polyvinylmethylsiloxane, which was crosslinked with potassium persulfate, revealed that the mean diameter of the droplets was 32 nm with a narrow distribution. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3587–3593, 2003     

Silicone elastomers with controlled surface composition using argon or hydrogen plasma treatment

Plasma treatment of poly(dimethyl siloxane) (PDMS) leads to changes in the surface composition that can be followed by X‐ray photoelectron spectroscopy (XPS). Prolonged plasma treatment in argon or hydrogen leads to an increase in oxygen, a decrease in carbon, and only minor changes in the silicon content. The extent of the change in elemental composition is dependent on the plasma conditions (e.g., the power and pressure during the treatment). We have determined how these parameters influence the surface composition of PDMS exposed to argon and hydrogen microwave plasma as a function of treatment time. A model has been developed describing the extent of change in surface composition under different plasma conditions. The power had a large impact on the rate of change in elemental surface composition, whereas the pressure had only a minor influence. We show that the rate of change in elemental composition can be described by one factor common for all treatments and one factor specific for each plasma condition of power, pressure, and gas. Using this model we can determine the plasma parameters and treatment time to obtain any desired extent of surface modification. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1378–1383, 2003     

含氟丙烯酸硅烷酯树脂的合成及其水解性能研究

研究了含氟丙烯酸硅烷酯树脂合成中单体滴加时间、反应温度和引发剂含量这3个因素对树脂分子量、分子量分布及反应放热的影响,确定了最佳合成工艺条件。通过红外光谱(FT-IR)和差示扫描量热仪(DSC)对树脂官能团和玻璃化转变温度进行分析,考察了丙烯酸硅烷酯单体含量、含氟丙烯酸单体含量及侧链甲基对树脂水解速率的影响。结果表明,树脂的水解速率随丙烯酸硅烷酯单体含量的升高而升高,随含氟单体含量的增加而降低,当合成所用的丙烯酸硅烷酯单体中不含有甲基时其水解速率比较大。     

New polymer materials based on silicone‐acrylic copolymer to improve fastness properties of reactive dyes on cotton fabrics

New polymer materials, based on silicone‐acrylic copolymer containing cationic groups, were synthesized through radical mechanism and ring‐opening polymerization of cyclosiloxane. The polymers of polyacrylate/polysiloxane improved the fastness properties of reactive dyes on cotton. In comparison with those of polyacrylate‐containing cationic groups, the wash fastness and wet rubbing fastness of the dyed cotton fabric treated with the new polymer materials were better. The handle of the fabric with aftertreatment was also good. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 720–725, 2006     

Complexation of titanium alkoxides with pentenoic acid and allylacetoacetate and their hydrolysis and addition reactions with H‐silanes

Complexation reactions of titanium tetraethoxide [Ti(OEt)₄] and titanium tetra‐n‐butoxide [Ti(OBuⁿ)₄] with 3‐pentenoic acid (PA) and allylacetoacetate (AAA), in a 1 : 1M ratio, were studied in ethanol solution at room temperature. ¹³C‐NMR and FTIR spectra showed that all PA and AAA completely reacted with both titanium alkoxides. Hydridosilane compounds such as triethoxysilane and triethylsilane were added to titanium chelate complexes in a 1 : 1M ratio. The investigation of products by ¹³C‐ and ²⁹Si‐NMR and FTIR showed additions of ? SiH to the C?C double bond. The hydrolysis of titanium–PA and AAA complexes, by water in 1 : 4 ratios, resulted in released PA in an amount of 10% and AAA of 20%. The stability of hydrolyzed products was investigated by ¹³C‐NMR, ²⁹Si‐NMR, and FTIR. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 790–796, 2005     

Effect of the particle size of Al2O3 on the properties of filled heat‐conductive silicone rubber

An elastomeric thermal pad with a thermal conductivity of 1.45 W/m K, needed for the heat dissipation of microelectronics, was obtained with hybrid alumina of different particle sizes as a filler and silicone rubber (vinyl‐end‐blocked polymethylsiloxane) as the matrix. The effects of the amount, particle size, and mixing mass ratio of the filler particles on the thermal conductivity and mechanical properties of silicone rubber were investigated. The results indicated that the thermal conductivity of the rubber filled with larger particles was superior to that of the rubber filled with the smaller grain size, and the rubber incorporated with a mixture of hybrid particles at a preferable mass ratio exhibited higher thermal conductivity than the rubber for which a filler with only a single particle size was used. In addition, the surface treatment of the hybrid filler with 3‐methacryloyloxypropyltrimethoxysilane could increase the thermal conductivity of the composite rubber. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1312–1318, 2007     

Surface wettability improvement of silicone elastomers synthesized with water‐soluble polyacrylic acid molds

The aim of this work was to evaluate the use of water‐soluble hydrophilic plastic molds for preparing siloxane based random copolymers and for enhancing the surface wettability of resultant polymers, with a view for contact lens manufacture. The random copolymer consisted of silicone monomers and a small amount of N‐vinyl‐2‐pyrrolidone (NVP) along with vinyl acetate and diethyleneglycoldiallylether as a crosslinker. The surface of this copolymer, which faced against a polyacrylic acid (PAA) mold, showed a higher degree of wettability compared to that obtained against a hydrophobic polypropylene (PP) mold. After heating at 80°C for 4 h, the surface of this copolymer became hydrophobic. When it was immersed in water, however, the high degree of surface wettability regained within 30 s, whereas no significant change in wettability was observed for the PP‐facing surface. The results obtained from X‐ray photoelectron spectroscopy indicated that the polar fraction, which is attributed to NVP fractions of the copolymer, concentrated at the vicinity of the PAA facing surface and, in consequence, improved the surface wettability. This surface also showed a dynamic rearrangement of the wettability in response to changes of the surrounding environment. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3786–3789, 2003     

Synthesis and properties of 4‐(ω‐methoxyoligodimethylsiloxanyl)butyl maleate: A new surfmer

Anionic reactive maleate with hydrophobic oligosiloxane chain was synthesized to use as a stabilizer in the batch and seeded emulsion polymerization of traditional monomers (acrylates, methacrylates, styrene, etc.). Polymerizable surfactant is obtained in a three‐step synthesis, starting from the anionic polymerization of cyclic siloxanes, followed by the silylation of methanol with the obtained cyclic oligomer, and finishing with the acylation of the linear oligomer by maleic anhydride. The improved technique of the synthesis of 4‐chlorobutoxydimethylchlorosilane, one of the initial substances for obtaining siloxane monomer, was elaborated. The anionic polymerization of octamethylcyclotetrasiloxane using cyclic alkoxysilane was carried out to form siloxane cyclic oligomer for the first time. The chemical structure of the monomer synthesized was confirmed by IR spectroscopy and functional analysis. Critical micelle concentration of the obtained surfactant was measured. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 310–313, 2004