Hydrogen-bonds structure in poly(2-hydroxyethyl methacrylate) studied by temperature-dependent infrared spectroscopy

Abstract

Hydrogen-bonds structure in poly(2-hydroxyethyl methacrylate) (PHEMA) were investigated by means of temperature-dependent infrared (IR) spectroscopy. Spectral variations involved with the OH…OH and C=O…HO types of hydrogen-bonds were found around the glass transition temperature of 80°C. Hydrogen-bonds among the hydroxyl groups gradually dissociate with increasing temperature. In contrast, discontinuous variation in the carbonyl bands was observed around the glass transition temperature. An association of the C=O…HO type of hydrogen-bond with increasing temperature above the glass transition temperature was revealed. These were concluded from the present study that hydrogen-bonds among the hydroxyl groups in each side chain terminal suppress the main chain mobility in the polymer matrix below the glass transition temperature, while the dissociation of the OH…OH type of hydrogen-bonds induces the association of the C=O…HO type of hydrogen-bond. As a result, the mobility of the main chain is induced by the change in hydrogen-bonds structure at the glass transition temperature.

Polymerization Kinetics of Poly(2-Hydroxyethyl Methacrylate) Hydrogels and Nanocomposite Materials

“…Several contributions from 3100-3700 cm −1 are identified in the O-H stretching region. According to Morita et al [26], the band at 3536 cm −1 is attributed to hydrogen-bonded hydroxyl groups, whereas at 3624-3660 cm −1 to free OH. According to Figure 13a, signals at the latter region were not identified in any material investigated.…”

“…The monomer, 2-hydroxyethyl methacrylate, contains one hydroxyl (-OH) and one carbonyl (C=O) group on its molecule. The C=O group acts only as the proton acceptor, while the OH group acts as both the proton donor and acceptor [26]. Hydrogen bonding between the monomer hydroxyl group and carbonyl oxygen atom strengthens the positive partial charges at the carbonyl C atom and at the double bond, as shown schematically in Scheme 1, leading to a significant charge transfer in the transition state of propagation [27].…”

“…The C=O group acts only as the proton acceptor, while the OH group acts as both the proton donor and acceptor [26]. Hydrogen bonding between the monomer hydroxyl group and carbonyl oxygen atom strengthens the positive partial charges at the carbonyl C atom and at the double bond, as shown schematically in Scheme 1, leading to a significant charge transfer in the transition state of propagation [27] ) have been found in many systems, including liquid alcohols and solid polymers [26]. It has been found that 53.7% of the OH group on the PHEMA side chain terminal contributes to the OH OH type of hydrogen-bond, while the remaining 47.3% are engaged in the C O OH =  type of hydrogen bond, at ambient temperature [26].…”

“…Hydrogen bonding between the monomer hydroxyl group and carbonyl oxygen atom strengthens the positive partial charges at the carbonyl C atom and at the double bond, as shown schematically in Scheme 1, leading to a significant charge transfer in the transition state of propagation [27] ) have been found in many systems, including liquid alcohols and solid polymers [26]. It has been found that 53.7% of the OH group on the PHEMA side chain terminal contributes to the OH OH type of hydrogen-bond, while the remaining 47.3% are engaged in the C O OH =  type of hydrogen bond, at ambient temperature [26]. When the nano-clay, OMMT, is added to the system, the clay platelets are partially exfoliated due to the ultrasound agitation and polymerization, by the insertion of the macromolecular chains in between the clay galleries, as was observed from XRD measurements.…”

Partitioning of coomassie brilliant blue into DMAEMA containing poly(HEMA)-based hydrogels

“…tetra(ethylene glycol) diacrylate (TEGDA), which, when added at varying concentrations, influence the modulus and the void volume through the cross-link density of the hydrogel [14,21]. However, such crosslinks may in addition be virtual and thus arise from hydrogen bonding [22,23], electrostatic interactions [24], polyplex formation [25], and molecular physical entanglements. Moreover, these hydrogels may be readily molecularly engineered to contain a wide variety of pendant and crosslinking bioactive moieties that render them biologically responsive wherein the response of the hydrogel is triggered by recognition of a biological agent conferred by an immobilized biorecognition species.…”