Silicone fouling-release coatings: effects of the molecular weight of poly(dimethylsiloxane) and tetraethyl orthosilicate on the magnitude of pseudobarnacle adhesion strength

Abstract

A series of poly(dimethyl siloxane) (PDMS)/silica nanocomposites were synthesized utilizing a sol gel method. The samples were evaluated using pseudobarnacle adhesion and tensile strength tests. The effects of the molecular weight of the PDMS and the size and structure of the silica domains on biofouling release and the mechanical behavior of the PDMS/silica materials were investigated. Three different molecular weights (18,000, 49,000 and 79,000 g mol 71 ) of hydroxyl-terminated PDMS (HT-PDMS) were used to prepare the nanocomposites with three different weight ratios (1:1, 3:1 and 5:1) of HT-PDMS to tetraethyl orthosilicate (TEOS). TEOS served as a crosslinker to form PDMS networks and as a precursor to form silica domains. Two different variants of TEOS with regard to its degree of polymerization (n) (monomeric type: n ffi 1 and oligomeric type: n ffi 5) were used for in situ formation of silica particles via the sol-gel process. The mechanical properties of the composites were characterized using stress-strain isotherms. All the mechanical properties evaluated (Young's modulus, tensile strength, energy required for rupture, elongation at break) improved with increases in the molecular weight of the HT-PDMS and the silica content. The pseudobarnacle adhesion test was used to examine the fouling-release (FR) properties of coatings applied on aluminum plates. The rupture energy and tensile strength increased substantially when oligomeric TEOS was employed in the PDMS/silica composites. Scanning electron microscopy (SEM) was used to investigate the structure of the silica domains. It was found that the use of oligomeric TEOS in higher molecular weight PDMS samples with higher PDMS/TEOS weight ratios led to low pseudobarnacle adhesion strengths of *0.3 MPa, which is in the range of commercial FR coatings.

Rigid Adherent-Resistant Elastomers (RARE): Nano-, Meso-, and Microscale Tuning of Hybrid Fluorous Polyoxetane–Polyurethane Blend Coatings

“…Such unfilled silicone coatings, whether condensation or hydrosilylation cured, are mechanically weak. Strain to break is typically ≤20%. , Strain to break for silica reinforced resins such as Dow Corning T4 is ∼400%, but Xie found that the force to remove a rigid bonded object, P c‑s , is relatively high (0.21 MPa) . Similarly, we found that P c‑s for (Dow Corning Sylgard 184) was 0.15–0.30 MPa depending on thickness.…”

Fouling Release Coating Consisting of Hyperbranched Poly(ε-caprolactone)/Siloxane Elastomer

“…The measurements were conducted on thick films (∼ 200 μm) according to ASTM Standard D 5618. , Typically, an aluminous cylindrical stud with 10 mm in diameter and 10 mm in height was bonded to the elastomer surface using an epoxy adhesive (Araldite). After being cured for 3 days under ambient conditions, the maximal shear force was recorded by a force gauge (SUNDOO SH-500) when the stud was moved parallel to the substrate at a constant rate.…”

Design of surfaces for controlling hard and soft fouling

“…Lowering the modulus of an elastic foulant-release coating has been shown by several researchers as an effective deterrent against algal plants [33] and barnacles (or pseudo-barnacles) [20,34]. A significant decrease in detachment force was observed when the coating modulus was reduced 10-1000 times lower than the foulant modulus [20,33,34,[287][288][289]. Chaudhury et al observed that the attachment of Ulva sporelings (young plants) was reduced by approximately 80% when modulus of a PDMS coating was reduced 12-fold.…”