Calorimetric study of block-copolymers of poly(n-butyl acrylate) and gradient poly(n-butyl acrylate-co-methyl methacrylate)

Abstract

The nanophase separation in diblock and triblock copolymers consisting of immiscible poly(n butyl acrylate) (block A) and gradient copolymers of methyl methacrylate (MMA) and n butyl acrylate (n BA) (block M/A) were investigated by means of their heat capacity, C p , as a function of the composition of the blocks M/A and temperature. In all copolymers studied, both blocks are represented by their C p and glass transition temperature, T g , as well as the broadening of the transition temperature range. The low temperature transition of the blocks A is always close to that of the pure poly(n butyl acrylate) and is independent of the analyzed compositions of the block copolymer, but broadened asymmetrically relative to the homopolymer due to the small phase size. The higher transition is related to the glass transition of the copolymer block of composition M/A. Besides the asymmetric broadening of the transition due to the phase separation, it decreases in T g and broadens, in addition, symmetrically with increasing acrylate content. The concentration gradient is not able to introduce a further phase separation with a third glass transition inside the M/A block.

Amphiphilic gradient copolymer of [poly(ethylene glycol) methyl ether] methacrylate and styrene via atom transfer radical polymerization

“…Gradient copolymers are of great interest because of their fascinating properties [1][2][3][4][5][6][7][8][9][10][11][12][13][14] and their simple synthesis via controlled/living radical polymerization (CRP) techniques, 15 such as atom-transfer radical polymerization (ATRP), 2,[16][17][18][19] reversible addition-fragmentation transfer (RAFT), 20,21 and nitroxide-mediated CRP. 4,6,[8][9][10][11][12][13][22][23][24] Gradient copolymers have also been synthesized using other living or pseudo-living polymerization methods such as ring-opening metathesis polymerization 7,14,25 and cationic polymerization.…”

Advanced analysis of poly(3-hydroxybutyrate) phases based on vibrational heat capacity

“…The series of experimental apparent heat capacities were obtained by standard DSC from the evaluation of measured heat flow rates at a heating rate of 10 K min -1 after previous cooling in range of 1-40 K min -1 . The temperature and heat flow rate calibration in the DSC apparatus were performed using parameters of melting indium [T m (onset) = 156.6°C, DH f = 28.45 J g -1 (3.28 kJ mol -1 )] [1,8,16]. In order to obtain accurate results, the heat capacity was calibrated to a sample of sapphire [1,8].…”

“…The temperature and heat flow rate calibration in the DSC apparatus were performed using parameters of melting indium [T m (onset) = 156.6°C, DH f = 28.45 J g -1 (3.28 kJ mol -1 )] [1,8,16]. In order to obtain accurate results, the heat capacity was calibrated to a sample of sapphire [1,8]. The temperature and heat flow were calibrated with indium metal (Lot J20J32) and heat capacity with sapphire (970345.901) (disks with mass: 93.449 mg (transparent) and 95.97 mg (red), obtained from TA Instrument, 970345.901) [23].…”

“…To study polymeric phases quantitatively, advanced thermal analysis in thermal characteristics and contents should be applied. Such analyses are very well described in the literature [1][2][3][4][5][6][7][8][9][10][11].…”

Gradient Methylidene-Ethylidene Copolymer via C1 Polymerization: an Ersatz Gradient Ethylene-Propylene Copolymer

“…Theoretical calculations indicate that gradient copolymers can undergo microphase separation with a blurred interface region between chemically different components. 3 These gradient copolymers are expected to have unique thermal properties, 4 particularly a broad glass transition temperature (T g ) range in situations where the corresponding homopolymers have very different T g s. 5 Experimental studies provided examples of materials containing incompatible comonomers with a very broad T g range. 6 In order to achieve a homogeneous gradient copolymer, all polymer chains must be initiated simultaneously and survive until the end of polymerization.…”