Preparation of PDMS Surface Modifier Using Silane-Functionalized Polymer Precursor Manufacture and Their Properties

실란 기능화 아크릴 고분자 전구체를 이용한 PDMS 표면 개질제 제조 및 표면 물성

Abstract

Plasma treatment and corona treatment have been used for surface modification of polydimethylsiloxane (PDMS) film by activating its surface with the -OH group. Adhesion promoter or coupling agent was also used to improve adhesion of PDMS film with various materials. However, obtained hydrophilicity onto the surface of PDMS films with those processes was transient and vulnerable. In this study, a new alkoxysilane-functionalized acrylic polymer precursor was first synthesized by copolymerization process, and then was reacted with HO-terminated PDMS through condensation reaction to prepare a new surface modifier for PDMS film. The structure and molecular weight of the prepared surface modifier were confirmed by 1H-NMR and GPC measurement. Surface properties of surface modifier-coated PDMS films were also investigated by using XPS, ATR and WCA analysis. The adhesion between the PDMS film and the surface modifier was tested using cross-cut test.

필름 형태의 Polydimethylsiloxane (PDMS)은 표면 개질을 하기 위해 Plasma 처리 또는 Corona 처리를 하여 표면을 -OH기로 활성화시키는 공정이나, 피착제와 PDMS 필름의 접착 또는 Adhesion promoter와 축합 반응을 통해 PDMS 표면을 다른 작용기로 개질시키는 공정, Grafting polymerization을 이용하는 PDMS 개질 공정이 주로 이용된다. 그러나 Plasma나 Corona 처리 후에 친수성이 오래가지 못하고, 보관에 어려움이 있다. 따라서, 본 연구에서는 코팅 공정을 통하여서 PDMS표면 개질을 하기 위해서, 먼저 새로운 형태의 실란 기능화 아크릴 고분자 전구체를 합성하고 이를 Hydroxyl-terminated PDMS와의 축합 반응을 통해 아크릴 고분자와 PDMS 고분자가 결합된 형태의 표면 개질제를 제조한 후, 이를 PDMS 필름 위에 코팅하였다. 제조한 표면 개질제의 구조와 분자량을 확인하기 위하여 1H-NMR과 GPC를 분석하였고, 표면 개질제가 코팅된 PDMS표면 특성 변화를 확인하기 위하여 XPS, ATR, WCA를 이용하여 표면 특성을 조사하였으며, PDMS 필름과의 부착을 확인하기 위해 Cross cutting test를 진행하였다. 그 결과 PDMS 필름 표면이 아크릴 고분자층이 형성된 것으로 확인하였고, PDMS 필름과 표면 개질제와의 부착성 (4 - 5B) 또한 우수한 것을 확인하였다.

Figure 1. Schematic presentation for physical surface modification process of PDMS.

Figure 2. Chemical surface treatment method using coupling agent.

Figure 3. Surface treatment using graft polymeri-zation.

Figure 4. Expected chemical structure of alkoxysilanefunctionalized acrylic polymer precursor.

Figure 5. Expected chemical structure of surface modifier prepared with reaction of MP copolymer with HO-PDMS.

Figure 6. Schematic presentation for microphase-separation occurring surface-modifier-coated PDMS film.

Figure 7. Surface modifier solutions prepared with reaction of MP copolymers with HO-PDMS at various compositions

Figure 8. FT-IR results of alkoxysilane-functionalized acrylic polymer precursor.

Figure 9. 1H-NMR result of (a) MP11 precursor, (b) MP21 precursor.

Figure 10. FT-IR results of alkoxysilane-functionalized acrylic polymer precursor.

Figure 11. ATR results of (a) unmodified PDMS film, (b) MP11-PDMS(1:2) coated PDMS film, (c) MP21-PDMS (1:2) coated PDMS film.

Figure 12. Water contact angles of unmodified PDMS film and surface modifier-coated PDMS film.

Figure 13. Cross cut test results of (a)MP11-PDMS (1:2) and (b)MP21-PDMS (1:2) coated PDMS films.

Table 1. Recipe for the synthesis of alkoxysilane-functionalized acrylic polymer precursors

Table 2. Synthetic recipe for surface modifier via condensation reaction between MP copolymers and hydroxyl-terminated PDMS(Weight ratio)

Table 3. Molecular weight of MP copolymers synthesized at different molar ratio of monomers

Table 4. XPS results of surface modifier-coated PDMS films and unmodified PDMS film

Table 5. Classification criteria according to ASTM D 3359