Synthesis and characterization of poly(vinyl alcohol-b-styrene)via atom transfer radical polymerization and saponification

Abstract

Poly(vinyl alcohol-b-styrene) (poly(VA-b-St)) diblock copolymer containing high syndiotactic poly (vinyl alcohol) (PVA) was synthesized by the saponification of poly(vinyl pivalate-b-styrene) (poly(VPi-b-St)). For the block copolymer, poly(vinyl pivalate) (PVPi) with trichloromethyl end group was obtained via telomerization of vinyl pivalate with carbon tetrachloride as a telogen and 2,2-azobisisobutyronitrile (AIBN) as an initiator. Then resulting poly(vinyl pivalate) with trichloromethyl end group was used as an efficient macroinitiator for the synthesis of poly(VPi-b-St) using atom transfer radical polymerization (ATRP) in the presence of CuCl/2,2'-bipyridine at 130 o C. The poly(vinyl pivalate) macroinitiator, poly(VPi-b-St), poly(VA-b-St) were characterized by GPC, FT-IR and 1 H-NMR. And the analysis showed that integrity of the block copolymer was maintained during saponification reaction.

CMC and dynamic properties of poly(VA-b-St) copolymer micelles for drug delivery

“…Poly(VA-b-St) block copolymers containing PVA with different tacticity were prepared as described in our previous papers [20,21]. The molecular characteristics of block copolymer are shown in Table 1.…”

Synthesis of poly(vinyl pivalate) by atom transfer radical polymerization in supercritical carbon dioxide

“…The small peak (g) at 0.8 ppm was attributed to the methyl protons of the initiator. The signal (b) at 2.1 ppm corresponded to the methylene protons of the monomer unit [25]. The resonance (a) at approximately 5.85 ppm attributed to the methine proton adjacent to terminal bromine at the x-end, which indicates the preservation of end group [46].…”

“…Later, these copolymers were employed as stabilizers in the dispersion polymerization of N-vinyl pyrrolidone, which yielded polymers with high conversion and molecular weight [15,28]. In addition, Li et al [25,47] reported the synthesis of poly(VPi-b-St) by ATRP using VPi telomer as a macroinitiator, where the telomer was prepared by radical telomerization of VPi using carbon tetrachloride. The structure of PVPi-b-PVAc synthesized in scCO 2 was confirmed by 1 H NMR (Fig.…”

“…On the other hand, controlling the radical polymerization of VPi is a challenge because unlike methacrylates and styrene, VPi lacks a conjugating substituent and its propagating radicals are quite reactive, less stable, and tend to undergo chain transfer and termination reactions. Living radical polymerization methods have been investigated to control the polymerization of VPi, such as the reversible additionfragmentation chain-transfer (RAFT) polymerization [15] and telomerization of VPi followed by block co-polymerization with styrene [25]. Recently our group reported the dispersion polymerization of VPi and CRP of vinyl acetate in scCO 2 [26,27].…”

Sodium cholate-enhanced polymeric micelle system for tumor-targeting delivery of paclitaxel

“…CMC, which is a measured physical parameter of micelles, refers to their thermodynamic stability. 39 The CMC of the block copolymers was determined by a fluorescence technique with pyrene as the probe. 40 Figure 1D shows the intensity ratios (I 1 :I 3 ) of pyrene monomer emission spectra versus the concentrations of micelles and micelles containing NaC (CMs), respectively.…”